[M]...James E. Maness, Bunge Corp., MO [U] Rep. Grain Elevator & Processing Society Guillermo A. Navas, Sheet Metal & Air Conditioning Contractors' Nat'l Assn., Inc., VA [M] Rep. Sheet

Technical Committee on Nonvoting

Handling and Conveying of Dusts, Vapors, and Gases

Murray A. Cappers, Jr., Chair Allied Signal Inc., NJ [U]

e R . Barton, Indianapolis, IN [U] s Chatrathl, Fike Corp., MO [M]

M. Cholln,J. M. Cholin Consultants Inc., NJ [SE] d G. Clark, du Pont de Nemours & Co., DE [U]

Ralph E. Collins, R. E. Collins Assoc., MA [SE] C. James Dahn, Safety Consulting Engr Inc., IL [SE] Vahid Ebadat, Chilworth Technology Inc~, NJ [SE] Walter L. Frank, EQE Int'l, Inc., DE [U] JcPcRaY E. George, The Chemithon Corp., WA [M] oseph P. Gillis, Westboro, MA [SE] harles L. Girard, Sandia Nat'l Laboratories, NM [U] Rep. NFPA Industrial Fire Protection Section

Dan A. Guarlcci, Fenwal Safety Systems/Williams Holdings, MA [M]

Ray Hunter, Ray Hunter & Assoc., Inc~, AL [M] Rep. American Air Filter

David C. Kirby, Union Carbide Corp., WV [M] James E. Maness, Bunge Corp., MO [U]

Rep. Grain Elevator & Processing Society Guillermo A. Navas, Sheet Metal & Air Conditioning Contractors'

Nat'l Assn., Inc., VA [M] Rep. Sheet Metal & Air Conditioning Contractors Nat'l Assn. Inc.

Robert W. Nelson, Pocasset, MA [I] Rep. Industrial Risk Insurers

Gary A. Page, American Home Products, NJ [M] Robert L.Peterson, Johnson& Higgins, NY [I] ames L. Roberts, Fluor Daniel, Inc., SC [SE] ynn K. Underwood, Wausau HPR Engr, WI [I]

John Valiulis, Factory Mutual Research Corp., MA [I] Harold H. Weber, Jr., The Sulphur Inst., DC [U]

(Vote Ltd. to NFPA 655) W. H. White, White Consulting Services, OH [SE]

Rep. TC Finishing Processes

Alternates

Henry L. Febo, Jr., Factory Mutual Research Corp., MA[I] (All. to J. Valiulis)

H[el~l? W. Garzia, Fenwal Safety Systems/Williams Holdings, MA

(Aft. to D. A. Guaricci) Paul F. Hart, Industrial Risk Insurers, IL [I]

(All. to R. W. Nelson) Gregory I. Hurst, Nat'l Starch & Chemical Co., IN [U]

(/kit. to J. R. Barton) Robert A. Koehler, Wausau HPR Engr, TX [I]

(/kit. to L. K. Underwood) Bernadette N. Reyes, Safety Consulting Engr, Inc., IL [SE]

(Ale to C. J. Dahn) It. F. Schwab, AlliedSignal Inc~, NJ [U]

(Alt. to M. A. Cappers) John H. Stratton, Sheet Metal & Air Con Contr Nat'l Assn., VA

[M] (All. to G. A. Navas)

Harry Verakls, U.S. Dept. of Labor, WV

Staff Liaison: Guy 1L Colonna

This list represents the membership at the time the Committee was balloted on the text of this edition. Since that time, changes in the membership may have occurred. A key to classifications is found at the back of this document.

Committee Scope: This Committee shall have primary responsibility for documents on the prevention, control, and extinguishment of fires and explosions in the design, construction, installation, operation and maintenance of facilities and systems processing or conveying flammable or combustible dusts, gases, vapors and mists.

The Report of the Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases is presented for adoption in 2 parts.

Part I of this Report was prepared by the Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases, and proposes for adoption amendments to NFPA 91-1995, Standard forExhaust Systems for Air Conveying of Materials. NFPA 91- 1995 is published in Volume 4 of the 1997 National Fire Codes and in separate pamphlet form.

Part I of this Report has been submitted to letter ballot of the Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases, which consists of 24 voting members. The results of the balloting, after circulation of any negative votes, can be found in the report.

The document when adopted will be redesig~nated as NFPA 91, Standard for Exhaust Systems for Air Conveying of Vapors, Gases, Mists, and Noncombustible Paniculate Solids.

Part II of this Report was prepared by the Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases, and proposes for adoption amendments to NFPA 655-1993, Standard forPreventinn o f Sulfur Fires and Explosions. NFPA 655-1993 is published in Volume 7 of the 1997 National Fire Codes and in separate pamphlet form.

Part H of this Report has been submitted to letter ballot of the Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases, which consists of 25 voting members. The results of the balloting, after circulation of any negative votes, can be found in the report.

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PART I Log #CP1)

91- 1 - (Title): Accept SUBMITI'ER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases RECOMMENDATION: Modify title as follows:

Standard for Exhaust Systems for Air Conveying of Vapors, Gases, Mists, and Noncombustible Particulate Solids. SUBSTANTIATION: The new title reflects the revised scope which excludes combustible particulate solids which are covered in NFPA 650, Standard for Pneumatic Conveying Systems for Handling Combustible Particulate Solids. COMMITI'EE ACTION: Accept. NUMBER OF COMMrlqT.E MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITIT.E ACTION:

AFFIRMATIVE: 21 NOT RETURNED: $ Peterson, Underwood, Valiulis

(Log #CP2) 91- 2 - (1-1.1 and 1-1.2 ): Accept SUBMITTER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases RECOMMENDATION: Revise existing 1-1.1 and a new 1-1.2 (renumber current 1-1.2 accordingly) to read as follows: 1-1.1 This standard provides minimum requirements for the

design, construction, installation, operation, testing, and maintenance of exhaust systems for air conveying of vapors, gases, mists, and noncombustible particulate solids except as modified or amplified by other applicable NFPA standards.

1-1.2 This standard does not cover exhaust systems for conveying combustible particulate solids. These materials are covered in other NFPA standards as noted in A-I.1. SUBSTANTIATION: The new scope reflects the exclusion of combustible particulate solids which are covered in other NFPA standards as well as additional text to clarify what is covered. A new section was added to emphasize that these materials are not covered, and to refer to the hst of NFPA standards that do cover these materials. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:

AFFIRMATIVE: 21 NOT RETURNED: 3 Peterson, Underwood, Valiulis

(Log #CP5) 91- 3 - (1-1.2): Accept SUBMITTER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases

] RECOMMENDATION: Delete the existing 1-1.2. SUBSTANTIATION: The text does not provide any additional requirements. In addition, the Committee does not believe it is within the scope of the committee to . . . . determine or grant specific authority to the AHJ (authority having jurrsdiction). COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:


(Log #CPt) 91- 4- (1-2.1): Accept SUBMrFFER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases RECOMMENDATION: Replace and renumber the existing 1-2.1 with the following text:

1-2. Purpose. The purpose of this standard is to provide I technical requirements for exhaust systems that will provide safety

to life and property from fires and explosions, and minimize the damage in the event that they occur. SUBSTANTIATION: The purpose was changed to be consistent with NFPA 654, Standard for Fire and Dust Explosions from the Manufacturing, Processing, and Handling or Combustible Particulate Solids, which is also under the jurisdiction of this Technical Committee, and also for further clarification. COMMITTEE ACTION: Accept.

NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:



[ RECOMMENDATION: Delete existing 1-2.2. SUBSTANTIATION: The text is not relevant to the purpose, therefore belongs elsewhere in the document. The first sentence of the existing 1-2.2 will go to Chapter 2, Design and Construction (See Committee Proposal 91-16 (Log #CP15). The last sentence of existing 1-2.2 is redundant to 7-1, therefore will be deleted altogether from the standard. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEEM MBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITYEE ACTION:


(Log #CP8) 91- 6 - (1-3): Accept SUBMITrER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases RECOMMENDATION: Replace existing text of 1-3 with the following:

Equivalency. Nothing in this standard is intended to prevent the use of systems, methods of, or devices of equivalent or superior quality, strength, fire resistance, effectiveness, durability, and safety over those prescribed by this standard, provided technical documentation is submitted to the authority having jurisdiction to demonstrate equivalency and the system, method, or device is approved for the intended purpose. SUBSTANTIATION: The equivalency section was modified to comply with the recommended language from the NFPA Committee Officers Guide. COMMITrEE ACTION: Accept. NUMBER OF COMMITI'EE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITIT.E ACTION:


(Log #CP9) 91- 7- (1.4): Accept SUBMITTER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases RECOMMENDATION: Replace existing text of 1-4 with the following:

1-4 Retroactivity. The provisions of this document are considered necessary to provide a reasonable level of protection from loss of life and property from fire and explosion. They reflect situations and the state of the art prevalent at the time the standard was issued.

Unless otherwise noted, it is not intended that the provisions of this document be applied to facilities, equipment, structures, or installations that were existing or approved for construction or installation prior to the effective date of the document, except in those cases where it is determined by the authority having jurisdiction that the existing situation involves a distinct hazard to life or adjacent property. SUBSTANTIATION: The retroactivity section was modified to comply with the recommended language from the NFPA Committee Officers Guide. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:


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(Log #CP10) 91- 8 - (1-5 Air Moving Device): Accept SUBMITTER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases RECOMMENDATION: Modify the existing definition for "Air Moving Device" in 1-5 with die text below.

The existing corresponding appendix item for the term will be deleted.

Air Moving Device. A power-driven fan, blower, or other device that establishes an airflow by moving a volume of air per unit time. SUBSTANTIATION: The definition was changed to be consistent with NFPA 654, Standard for Fire and Dust Explosions from the Manufacturing, Processing, and Handling or Combustible Particulate Solids. The existingAppeudix item was deleted because it was included in t h e b o d y of the proposed modification of the definition. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:


(Log #CP11) 91- 9 - (1-5 Duct): Accept SUBMITTER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases

] RECOMMENDATION: Modify the existing definition of "Duct" in ] 1-5 to read as follows: J Duct. Pipes, tubes, or other enclosures used for the purpose of I pneumatically conveying materials.

SUBSTANTIATION: The definition was changed to be consistent with NFPA 650, Standard for Pneumatic Conveying Systems for Handling Combustible Materials, which is also under the jurisdiction of this Technical Committee. COMMITTEE ACTION: Accept. NUMBER OF COMMrFrEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:


(Log #CP12) 91- 10- (1-5 Dust): Accept SUBMYITER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases

[ RECOMMENDATION: Delete existing definition of "DusC in 1-5. SUBSTANTIATION: This term is nei ther necessary nor essential for readers to use the standard. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:


(Log #CP26) 91- 11 - (1-5 Limited-Combustible): Accept SUBMFFrER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases RECOMMENDATION: Modify the existing definition of ~Limited- Combustible ~ in 1-5 to read as follows:

Limited-Combustible. A building construction material not complying with the definition of noncombustible material that, in the form in which it is used, has a potential heat value not exceeding 3500 Btu / lb (8141 kJ/kg), where tested in accordance with NFPA 259, Standard Test Method for Potential Heat of Building Materials, and complies with (a) or (b) below. Materials subject to increase in combustibility or flame spread index beyond the limits herein established through the effects of age, moisture, or other atmospheric condition shall be considered combustible.

(a) Materials having a structural base of noncombustible material, with a surfacing not exceeding a thickness of 1 /8 in. (3.2 mm) that has a flame spread index not greater than 50.

(b) Materials, in the form and thickness used, other than as described in (a), having nei ther a flame spread index greater than 25 nor evidence of continued progressive combustion and of such composition that surfaces that would be exposed by cutting through the material on any plane would have nei ther a flame

spread index greater than 25 nor evidence of continued progressive combustion. SUBSTANTIATION: This definition complies with the term used in NFPA 220, Standard on Types of Building Construction, which is the preferred definition in the draft NFPA Glossary of Terms. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:


(Log #CP14) 91- 12 - (1-5 Listed, Labeled, Shall): Accept SUBMITTER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases

RECOMMENDATION: Replace exisdng definitions and corresponding Appendix items of the terms "Approved", "Listed" and ~Authority Having Jurisdiction" in 1-5 with the following:

Approved*. Acceptable to the authority having jurisdiction. A-l-5 Approved. The National Fire Protection Association does

not approve, inspect, or certify any installations, procedures, equipment, or materials; nor does it approve or evaluate testing laboratories. In determining the acceptability of installations, procedures, equipment, or materials, the ~authority having jurisdiction" may base acceptance on compliance with NFPA or other appropriate standards. In the absence of such standards, said authority may require evidence of proper installation, procedure, or use. The "authority having jurisdiction" may also refer to the listings or labeling practices of an organization that is concerned with product evaluations and is thus in a position to determine compliance with appropriate standards for the current production of listed items.

Listed*. Equipment, materials, or services included in a list j~ublished by an organization acceptable to the authority having

risdiction and concerned with evaluation of products or services, at maintains periodic inspection of production of listed

equipment or materials or periodic evaluation of services, and whose listing states that either the equipment, material, or service meets identified standards or has been tested and found suitable for a specified purpose.

A-1.5 Listed. The means for identifying listed equipment may vary for each organization concerned with product evaluation; some organizations do not recognize equipment as listed unless it is also labeled. The authority having jurisdiction should utilize the system employed by the listing organization to identify a listed product.

Authority Having Jurisdiction. The organization, office, or individual responsible for approving equipment, an installation, or aprocedure .

A-l-5 Authority Having Jurisdiction. The phrase "authority havingjurisdictlon" is used in NFPA documents in a broad manner since jurisdictions and approval agencies vary, as do their responsibilities. Where public safety is primary, the authority having jurisdiction may be a federal, state, local, or other regional depar tment or individual such as a fire chief; fire marshal; chief of a fire prevention bureau, labor department, or health department; building official; electrical inspector; or others having statutory authority. For insurance purposes, an insurance inspection department, rating bureau, or other insurance company representative may be the authority having jurisdiction. In many circumstances, theproper ty owner or his or her designated agent assumes the role o f the authority having jurisdiction; at government installations, the commanding officer or departmental official may be the authority having jurisdtction. SUBSTANTIATION: The definitions were modified to comply with the recommended language from the NFPA Regulations. In addition, as suggested by the NFPA Manual of Style, the notes were moved to Appendix items since they were advisory in nature. COMMI'ITEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:

AFFIRMATIVE: 21 NOT RETURNED: 3 Peterson, Underwood, Valinlis

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(Log #CPI 3) 91- 13 - (1-5 Noncombustible Particulate Solid (New)): Accept SUBMITTER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases RECOMMENDATION: Add a new term, "Noncombustible

[ Particulate Solid", and corresponding definition in 1-5. ] Noncombustible Particulate Solid. Any noncombustible solid

material, . . . . composed of distinct particles or pieces, re. dless or size, shape, or chemical composition. Noncombus~v~

| particulate solids include dusts, fibers, fines, chips, chunks, flakes, | or mixtures of these.

SUBSTANTIATION: This term and corresponding definition was added to maintain consistency with NFPA 654, Standard for Fire and Dust Explosions from the Manufacturing, Processing, and Handling or Combustible Particulate Solids, also under the jurisdiction of the Technical Committee. The revised title and scope [See Committee Proposal 91-1 (Log #CPI) and 91-2 (Log #CP2)] use this term, therefore must be dearly defined. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:


(Log #CP25) 91- 14- (1-5 Should): Accept SUBMITTER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases

[ RECOMMENDATION: Delete the existing term and definition of [ "Should" in 1-5.

SUBSTANTIATION: The term "should" is not used in the body of the standard since the body is reserved for mandatory language, per NFPA Manual of Style. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:



I RECOMMENDATION: Modify the existing 2-1.1 and renumber to read:

2-1.2 The design of any exhaust system shall consider the physical and chemical properties and hazardous characteristics of the materials being conveyed. SUBSTANTIATION: Editorial change: "hazard" to "hazardous". COMMITTEE ACTION: Accept. NUMBER OF COMMITIT_.E MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:


(Log #CP15) 91- 16- (2-1.1 (New)): Accept SUBMITTER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases RECOMMENDATION: Insert a new 2q.1, and renumber the existing 2-1.1 and subsequent sections accordingly. It shall read:

2-1.1 The design and installation of exhaust systems shall be the responsibility of persons having a knowledge of these systems. SUBSTANTIATION: This text was moved from the existing 1-2.2 (See Committee Proposal 91-5 (Log #CP7) and moved to this section because it relates to Chapter 2, Design and Construction. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:

AFFIRMATIVE: 20 NEGATIVE: 1 NOT RETURNED: 3 Peterson, Underwood, Valiulis

EXPLANATION OF NEGATIVE: CHOLIN: The text of this proposal is acceptable. However, this

text does NOT belong as a subparagraph to 2-1.1. Subparagraphs to 2-1.1 should be reserved for embellishments of the core idea in 2-1.1, not for introducing an entirely new, albeit good, idea. 2- 1.1.1 should be renumbered 2-1.2 and subsequent paragraphs renumbered accordingly.

(Log #CP19) 91- 17- (2-1.1.2 (New)): Accept SUBMITTER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases

I RECOMMENDATION: Create a new secdon 2-1.1.2 to read: 2-1.1.2 In systems conveying flammable vapors, gases or mists, the

concentration shall not exceed 25 percent of the Lower Flammability Limit.

Exception: Higher concentrations shall be permitted if the exhaust system is designed and protected in accordance with NFPA 69, Standard for Explosion Prevention Systems using one or more of the following techniques:

(a) combustible concentration reduction, (b) oxidant concentration reduction, (c) deflagration suppression, or (d) deflagration pressure containment.

SUBSTANTIATION: This new section was added to provide guidance for exhausting flammable vapors, mists, and gases which might approach or exceed the lower flammable limit by reference to the appropriate techniques described in NFPA 69, Standard for Explosion Prevention Systems. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:



text does NOT belong as a subparagraph to 2-1.1. Subparagraphs to 2-1.1 should be reserved for embellishments of the core idea in 2-1.1, not for introducing an entirely new, albeit good, idea. 2-1.1.2 should be renumbered 2-1.3 and subsequent paragraphs renumbered accordingly.

CLARK: Recommended Section 2-1.1.2 excludes the use of adequately designed explosion vents (NFPA 68) as an acceptable means to reach an appropriate level of safety. However, NFPA 68, Chapter 8, deals with this technique. Either it should be listed here as an "acceptable alternative" or the NFPA 68/69 committee should withdraw NFPA 68, Chapter 8. I support the former.

(Log #CPI7) 91- 18- (2-1.3): Accept SUBMITTER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases

[ RECOMMENDATION: Move the existing 2-1.3 and the [ corresponding Appendix item A-2-1.3 to a new section 2-1.1.1 and [ A-2-1.1.1 as follows: ] 2-1.1.1" Incompatible materials shall not be conveyed in the [ same system. [ A-2-1.1.1 Materials when mixed should not create a fire, [ explosion, or health hazard.

SUBSTANTIATION: This section and corresponding Appendix item were moved to be a subsection of the new proposed 2-1.1 (See Committee Proposal 91-16 (Log #CP15) since the proposed 2-1.1 first introduces the requirement of consideration of physical and chemical properties and hazard characteristics of the materials being conveyed. The new sections are related to these properties and hazard characteristics. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:


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text does NOT belong as a subparagraph to 2-1.1. Subparagraphs to 2-1.1 should be reserved for embellishments of the core idea in 2-1.1, not for introducing an entirely new, albeit good, idea~ 2-1.3 should be renumbered 2-1.4 and subsequent paragraphs renumbered accordingly.

(Log #CP21) 91- 19- (2-1.5): Accept SUBMITTER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases

[ RECOMMENDATION: Delete the existing 2-1.5 and renumber [ subsequent sections accordingly.

SUBSTANTIATION: This was deleted because the shape of the duct is irrelevant to the standard and there could be other duct shapes in use. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:


(Log #CP22) 91- 20 - (2-1.6, 2-1.7 (New)): Accept SUBMITTER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases RECOMMENDATION: Revise the text of existing 2-1.6. It will read as follows:

2-1.7 Fire dampers, fire stops, and fire interruption devices shall not be installed in exhaust systems. SUBSTANTIATION: In addition to the prohibition of the installation of fire dampers, other items' installation were also PclrOhibited because the term "fire dampers" does not adequately

escribe all the devices that are used inside exhaust duct systems, and that the Committee wished to prohibit interior devices from the duct.

In the modified 2-1.7, the existing exception was deleted because the Committee felt that it allowed possible health and fire hazards to the occupants of the area from which material is being exhausted. COMMI'VI'EE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:


EXPLANATION OF NEGATIVE: NELSON: This section prohibits the use of devices specifically

listed for that purpose.

(Log #CP$0) 91- 21 - (2-1.8): Accept SUBMITTER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases

[ RECOMMENDATION: Insert a new section to read as follows: ] 2-1.8 Exhaust ducts shall not pass through fire walls as defined by ] NFPA 221, Standard for Fire Walls and Fire Barrier Walls.

SUBSTANTIATION: This new section was added to clarify the Committee's intent that ducts shall not pass through standard fire walls, as defined in NFPA 221 under any condition. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:


(Log #CP31) 91- 22- (2-1.9 (New)): Accept SUBMITTER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases

] RECOMMENDATION: Add a new section 2-1.9 to read as [ follows: [ 2-1.9 Ducts that pass through a fire barrier wall having a fire [ resistance rating of 2 hours or more shall meet the following:

I (a) Be constructed and supported so that 10 ft (3 m) of the duct on each side of the fire barrier can resist a 2 hour fire scenario.

(b) Be protected by sealing the opening around the duct with a listed or approved material of a fire resistance rating equivalent to that of the fire barrier wall. SUBSTANTIATION: This section was added to clarify the requirements where a duct passes through a two hour or greater rated fire barrier wall, as defined in NFPA 221. This addition also allows more consistency with NFPA 650 (this consistency does not include fire dampers now prohibited in NFPA 91, but are permitted in specific scenarios in NFPA 650) COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:


(Log #CP32) 91- 23 - (2-1.10 (New)): Accept SUBMITTER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases

I RECOMMENDATION: Add a new section 2-1.10 as follows: 2-1.10 Ducts that pass through a fire barrier wall having a fire

resistance rating of less than 2 hours shall be protected by sealing the opening around the duct with a listed or approved material of a fire resistance rating equivalent to that of the fire barrier wall. SUBSTANTIATION: This section was added to clarify the requirements where a duct passes through a two hour or greater rated fire barrier wall, as defined in NFPA 221. This addition also allows more consistency with NFPA 650 (this consistency does not include fire dampers, now prohibited in NFPA 91, but are permitted in specific scenarios in NFPA 650). COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:

AFFIRMATIVE: 21 NOT RETURNED: ~ Peterson, Underwood, Valiulis

(Log #CP27) 91- 24 - (2-1.11 (New)): Accept SUBMITTER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases RECOMMENDATION: Modify the text of existing 2-1.7 and renumber to read as follows:

2-1.11 Fire detection and alarm systems shall not be interlocked to shut down air moving devices.

Exception No. 1: When shut down is necessary for the effective operation of an automatic extinguishing system.

Exception Nc 2: A documented risk analysis acceptable to the authority having jurisdiction shows that the risk of damage from fire and the products of combustion would be higher with air moving devices operating. SUBSTANTIATION: The existing 2-1.7 was modified because the use of fire dampers was eliminated, therefore existing exception 1 was deleted. The remaining exceptions were rewritten for clarification. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:


EXPLANATION OF NEGATIVE: NELSON: This practice prohibits the use of plastic duct with

interrupters which are listed for this purpose.

(Log #CP3) 91- 25 - (2-2.1): Accept SUBMITTER: Technical Committee on Handling and Convey!ng of Dusts, Vapors, and Gases RECOMMENDATION: Modify existing 2-2.1 as follows:

2-2.1 Duct material shall be noncombustible. Exception No. l: Alternative material shall be permitted to be

used when the material being conveyed is incompatible with noncombustible construction materials.

Exception No. 2: Listed duct systems that do not require mechanisms internal to the duct and that have been evaluated and

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I found to be of low fire hazard not requiring automatic sprinkler protection to prevent fire spread.

Exception No. 3: Plastic duct systems used for handling noncombustible material or flammable corrosive vapors and that have automatic sprinkler protection as required by Chapter 6, Fire Protection. SUBSTANTIATION: The revision of 2-2.1 allows various acceptable alternatives to non-combustible ducts. The Committee eliminated the use of non-listed limited-combustible ducts. The Committee acknowledged that the use of some limited- combustible construction materials for ducts may be hazardous. It was also acknowledged through the addition of Exception No. 2 that there are now "listed" duct systems which do not require

rinkler systems. MMITTEE ACTION: Accept.

NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:

AFFIRMATIVE: 20 NEGATIVE: 1 NOT RETURNED: 3 Peterson, Underwood, Valiulls

EXPLANATION OF NEGATIVE: COLLINS: Under the substantiation, a statement is made to the

effect that the committee acknowledges that the use of some limited-combustion construction materials may be hazardous; however, technical substantiation was not presented. One committee member made reference to Factory Mutual loss experience but could not relate the cause of losses to the use of limited-combustible construction materials. Further, statements were made to the effect that limited-combustible lacks definition. To the contrary, clear definition is presented in NFPA 220 and NFPA 259 as well as other Fire Test Standards. The result of deleting the use of limited-combustible construction materials is therefore believed to be unnecessarily restrictive. This result seems to me to be contrary to NFPA purpose and policy.

(Log #CP24) 91- 26 - (2-2.2): Accept SUBMITTER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases RECOMMENDATION: Modify existing 2-2.2 to read as follows:

2-2.2 The duct construction shall conform to applicable Sheet Metal and Air-Conditioning Contractors' NationalAssociation, Inc. (SMACNA) standards:

(a) Accepted Industry Practice for Industrial Duct Construction (1975),

(b) Rectangular Industrial Duct Construction Standard (1980), (c) Round Industrial Duct Construction Standard (1977), (d) Thermoplastic Duct (PVC) Construction Manual (1995), (e) Thermoset FRP Duct Construction Manual (1997)

SUBSTANTIATION: New edition references were added for the documents to reference the latest edition. The existing exception was deleted because the addition of proposed item (e) made it redundant. In addition, the acronym SMACNA was spelled out since this was the first use of the acronym. COMMITTEE ACTION: Accept. NUMBER OF COMMrI'FEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:


(Log #CP23) 91- 27- (2-2.3): Accept SUBMITTER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases

[ RECOMMENDATION: Modify the existing text of 2-2.3 and delete [ the exception to read:

2-2.3 Duct supports shall be designed to carry the weight of the duct system itseff plus the anticipated weight of any conveyed

[ materials. If sprinkler protection is provided inside the duct ] system, then the duct supports shall also be designed to carry the

anticipated weight of any accumulation of sprinkler discharge. SUBSTANTIATION: The Committee adopted language from NFPA 650, Standard for Pneumatic Conveying Systems for Handling Combustible Materials, which is also under the jurisdiction of the Technical Committee providing consistency. In addition, the new requirement provides a performance based requirement versus the existing prescriptive requirement. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24

VOTE ON COMMITTEE ACTION: AFFIRMATIVE: 21 NOT RETURNED: 3 Peterson, Underwood, Valiulis

(Log #CP33) 91- 28 - (2-3.3): Accept SUBMI'I~I'ER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases RECOMMENDATION: Modify the existing 2-3.3 and delete the associated Figure 2-3.3 and follows:

2-3.3* Access openings shall he sized to satisfy their intended purpose.

A-2-3.3 Access into ducts is required toper form intended inspection, to clean interior surfaces, a n d t o service or replace devices located inside the duct. SUBSTANTIATION: The information on the sizing of doors was somewhat arbitrary, and not based on technical data. In addition, general information on the design of access openings is covered in SMACNA construction standards, which are referenced in Chapter 8. The new text provides performance-based requirements. COMMITTEE ACTION: Accept. NUMBER OF COMMITrEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:

AFFIRMATIVE: 21 NOT RETURNED: 3 Peterson, Underwood, Vallulis

(Log #CP35) 91- 29 - (2-4.5.1, A-2-4.5.1 (New)): Accept SUBMITTER= Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases RECOMMENDATION: Modify the existing 2-4.5.1 and add corresponding appendix as follows:

2-4.5.1" Terminations with discharge to atmosphere shall be safely arranged.

A-2-4.5.1 Discharge should terminate away from outside air intakes to prevent material from entering the air intakes. For duct systems containing flammable or combustible materials, an evaluation is necessary to determine adequate exhaust stack termination design. Information on stack height can be found in the ASHRAE Handbook, Fundamentals Volume, Chapter 14, "Airflow Around Buildings" or the ACGIH Ventilation Manual. SUBSTANTIATION: A majority of the information was moved to the Appendix because the Committee did not want to attempt to establish requirements for every possible scenario. In addition, the modified requirement is now performance based. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:


(Log #GP34) 91- 30 - (2-4.7): Accept SUBMIq['I'ER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases

I RECOMMENDATION: Revise the existing 2-4.7 to read as I follows:

2-4.7* Va ors containing residues or noncombustible articulate I solids shall ~e filtered. P

SUBSTANTIATION: The wording was clarified to reflect the new title and scope (See Committee Proposal 91-1 (Log #CP1) and 91-2 (Log #CP2). COMMITTEE ACTION: Accept. NUMBER OF COMMI'FFEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:


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(Log #CP4) 91- 31 - (2-4.8): Accept SUBMITTER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases RECOMMENDATION: Revise existing 2-4.8 to read as follows:

2-4.8 Duct liners that are combustible shall meet one of the following requirements:

(a) Liners tested as part of a listed duct system which have been evaluated and found to be of low fire hazard not requiring automatic sprinkler protection to prevent fire spread,

(b) Liners used for handling noncombustible material or flammable corrosive vapors and that have automatic sprinkler protection as required by Chapter 6, Fire Protection. SUBSTANTIATION: The revision of 2-4.8 allows various acceptable alternatives to non-combustible liners. The previous inclusion of limited-combustible liners was eliminated. The Committee acknowledged that the use of some limited- combustible construction materials for duct liners may be hazardous. COMMITTEE ACTION: Accept. NUMBER OF COMMrl"rEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:


(Log #CP36) 91- 32- (2-6): Accept SUBMITrERa Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases RECOMMENDATION: Delete the existing Section 2-6 Duct Clearances and replace with the Section 2-6 Duct Clearances from the Fall 1997 Report on Comments for NFPA 650. It will read as follows:

2-6 Duct Clearances. 2-6.1 All ductwork and system components handling

combustible material and operating at less than 140°F (60°C) shall have a clearance of not less than 18 in. (46 cm) from combustible construction or any combustible material. Exception No. h When the ductwork system is equipped with an approved automatic extinguishing system designed for the specific hazard, the clearance shall be permitted to be reduced to 6 in. (15 cm) from combustible materials and 1/2 in. (13 ram) from combustible construction. Exception No. 2: The combustible material and construction is protected by the use of materials or products listed for protection purposes or in accordance with Table 2-6.1.

2-6.1.1 Spacers and ties for protection materials shall be of noncombustible material and shall not be used directly behind the duct.

There shall be at least 1 in. (2.5 cm) between the wall protector and combustible walls and ceilings for clearance reduction systems using a ventilated space.

2-6.1.3 Mineral wool batts (blanket or board) shall have a minimum density of 8 Ib per ft 3 (3.6 kg/m s) and have a minimum melting point of 1500°F (816°C).

2-6.1.4 Insulation board used as a part of a clearance reduction system shall have a thermal conductivity of I Btu-in./ftLhr-°F (0.14 w/m~-hr-°C) or less. Insulation board shall be formed of noncombustible material.

2-6.1.5 There shall be at least 1 in. (2.5 cm) between the duct and the wall protector. In no case, shall the clearance between the duct and the wall surface be reduced below that shown in the Table 2-6.1.

2-6.2 Duct systems operating at elevated temperatures above 140°F (60°C) shall have clearances from combustible building construction or any combustible material of not less than 18 in. (46 cm).

2-6.3 Where clearance is reduced by using an air space between the combustible wall and the wall protector, air circulation shall

! be provided by one of the following methods. 2-6.3.1 Air circulation shall be permitted to be provided by

leaving all edges of the wall protector open with at least a 1 in. (2.5 cm) air gap.

2-6.3.2 f f the wall protector is mounted on a single flat wall awayfrom corners, air circulation shall be permitted to be

I provided by one of the following: (a) Leaving top and bottom edges open to circulation by

maintaining the 1 in. (2.5 cm) air gap I (b) Leavingtop and both side edges open to circulation 1 maintaining the 1 in. (2.5 cm) air gap

2-6.3.3 Wall protectors that cover two walls in a corner shall be permitted to be open at the top and bottom edges with at least a 1 in. (2.5 cm) air gap.

All clearances shall be measured from the outer surface of the combustible material to the nearest point on the outer surface of the duct, disregarding any intervening protection applied to the combustible material. Clearances shall be measured as shown in Figure 2-6.4. Clearances with protection provided shall be calculated by using the equation as shown as dimension B in Figure 2-6.4.

Cp, = C~ x (1- R/IO0) where

Cpr = the minimum allowable clearance with protection. C~ = the required clearance with no protection. R = the maximum allowed reduction in clearance.

Table 2-6.1 Reduction of Duct Clearance with Specified Forms of Protection Clearance reduction applied to and covering all combustible surfaces within the distance specified as required clearance with no protection in 2-6.2, and Table 2-6.3.

Form of Protection (a) 31/e-in. (90-mm) thick masonry wall without ventilated air s~ace ( ) 1/2-in. (13-mm) thick noncombustible insulation board over 1-in. (25.4-mm) glass fiber or mineral wool batts without ventilated air space (c) 0.024 in./0.61 mm (24 gauge) sheet metal over l-in. (25.4- ram) glass fiber or mineral wool batts reinforced with wire, or equivalent, on rear face with at least a 1-in. (25.4-mm) air gap

1 (d) 3 /e-in. (90-mm) thick masonry wall with at least a 1-in. (25.4-mm) air gap (e) 0.024 in./0.61 mm (24 gauge) sheet metal with at least a 1-in. (25.4-mm) air gap (f) t/e-in. (13-ram) thick noncombustible insulation board with at least a 1-in. (25.4-mm) air gap (g) 0.024 in./0.61 mm (24 gauge) sheet metal with ventilated air space over 0.024 in./0.61 mm (24 gauge) sheet metal with at least a 1-in. (25.4-mm) air gap (h) bin. (25.4-mm) glass fiber or mineral wool batts sandwiched between two sheets 0.024 in./0.61 mm (24 gauge) sheet metal with at least a 1-in. I25.4-mmt air ~[ap

2-6.1.2 With all clearance reduction systems using a ventilated air space, air circulation shall be provided as described in 2-6.4.

Maximum allowable reduction in clearance (percent)

As Wall Protector As Ceiling Protector 33%

50% 33%

66% 66%

66%

66% 50%

66% 50%

66% 5o%

66% 5o%

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f Construction using ~ __ Sheet metal or combustible material ~ / ~ other protection

t

N N ~ z N N

i Duct

Duct

resistant plastics have heat limitations that shall be considered when designing a system. The following minimum standards of materials, construction, and workmanship shall be deemed necessary to ensure minimum fire hazard in the operation of these systems.

3-1.2 Plastic ducts shall be in accordance with 2-2.1 and 2.4.8. All hoods and air moving device surfaces that are part of the system shall have flame spread ratings at least equivalent to the flame spread rating of the material of the duct system. SUBSTANTIATION: The modifications were made to comply with modifications to other sections of the document, and to eliminate redundancies. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:


Sheet metal or

A equals the required clearance with no protection. B equals the reduced clearance permitted. The protection applied to the construction using combustible material shall extend far enough in each direction to make C equal to A,

(Log #CP39) 91- 35 - (331.3): Accept SUBMITTER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases RECOMMENDATION: Modify 331.3 as follows:

Plastic duct materials shall be listed with an external smoke development rating of 50 or less when located in a multistory building or a concealed space.

Exception No. 1: Duct systems that are located in an area protected by an automatic sprinkler system.

Exception No. 2: Duct systems that are located in a one hour fire- rated enclosure. SUBSTANTIATION: In the exception, ~one hour" was added to provide ~uidance to the user about the fire rating. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITrEE ACTION:

AFFIRMATIVE: 21 NOT RETURNED: $ Peterson, Underwood, Valiulis

Figure 2-6.4 Extent o f protection required to reduce clearances from duets.

SUBSTANTIATION: This will provide consistency within documents on adequate duct clearances within thejurisdict lon of the same Technical Committee (NFPA 650 and NFPA 91). COMMITI'EE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:


(Log #CP37) 91- 33 - (Chapter 3, Tide): Accept SUBMITTER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases

[ RECOMMENDATION: Chan~e the existing title of Chapter 3 to I "Chapter 3 Corrosive Materials .

SUBSTANTIATION: The chapter title was chan~ed to reflect the new document title and scope. The word "fume was removed because it is not defined in the document, and is covered in the PcrOposed tide change.

OMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:


(Log #CP38) 91- 34 - (3-1.1, 3-1.2): Accept SUBMITTER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases

I RECOMMENDATION: Modify the existing 331.1 and 331.2 to read [ as follows: I 3-1.1 Exhaust systems utilizing plastic materials shall be [ permitted to convey corrosives. The choice of the material type I shall be the responsibility of the design engineer. All chemical-

(Log #CP28) 91- 36 - (Chapter 5): Accept SUBMITTER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases RECOMMENDATION: Modify current Chapter 5 as follows:

Chapter 5 Ignition Sources 5-1 Electrical Equipment. All electrical equipment and

installations shall comply with the requirements of NFPA 70, National Electxical Code®.

5-2* Static Electricity. A-5-2 See NFPA 77, Recommended Practice on Static Electricity,

for information on this subject. 5-2.1" All system components shall be conductive. Bonding and

grounding with a resistance of less than 1.0 x 10 6 Ohms to ground shall be provided. Exception: Nonconductive equipment shall be permitted to be used as covered in this document by Chapter 3, Corrosive Materials.

A-5-2.1 Bonding minimizes the potential difference between conductive .°b'ects9 . Grounding minimizes the potential difference between objects and ground.

I Using metal ducts with non-conductive plastic liners to convey I mists and particulate solids can create a propagating brush | discharge ignition or shock or both. I 5-2.2 Where belt drives are used, the belts shall be electrically [ conductive at 1 megohm or less.

5-3 Operations generating flames, sparks or hot material such as from grinding wheels and welding, shall not be manifolded into any exhaust system that handles flammable or combustible materials.

5-4 Open Flames and Sparks. The requirements of 5.4.1 through 5.4.3 shall be applied retroactively.

5.4.1 Cutting and welding shall comply with the applicable requirements of NFPA 51B, Standard for Fire Prevention in Use of Cutting and Welding Processes.

5-4.2 Grinding, chipping, and other operations that produce either sparks or open flame ignition sources shall be controlled by a hot work permit system in accordance with NFPA 51B, Standard for Fire Prevention in Use of Cutting and Welding Processes.

5.4.3 Smoking shall be permitted only in designated areas.

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N F P A 91 - - F9 8 R O P

5-5 Ferrous materials capable of igniting combustible material being conveyed shall be removed from the exhaust stream by magnetic separators of the permanent or electromagnetic type. Where electromagnetic separators are used, provisions shall be made to indicate the loss of power to the electromagnetic separators.

5-6* Belt drives shall be designed to stall without the belt slipping, or a safety device shall be provided to shut down the equipment if slippage occurs.

A-5.6 Transmission of power by direct drive should be used where possible in preference to belt or chain drives.

5-7* Bearings. Roller or ball bearings shall be used on all processing and transfer equipment. Lubrication shall be performed in accordance with the manufacturer's recommendations. Exception: Bushings shall be permitted to be used when an engineering evaluation shows that mechanical loads and speeds preclude ignition due to frictional heating.

A-5-7 Consideration should be given to the potential for overheating caused, by dust. entry into bearings. Bearings should he located outside the exhaust stream where they are less exposed and more accessible for inspection and service. Where bearings are in contact with particulate solid streams, sealed or purged bearings are preferred.

5-8 Equipment. Equipment with moving parts shall be installed and maintained so that true alignment is maintained and clearance is provided to minimize friction. SUBSTANTIATION: This Chapter was revised from the changes made by this Committee to NFPA 650, as appears at the time of the Committee meeting in the F97 Report on Comments. It more fully addresses the most likely ignition sources and maintains conformity with other standards under the jurisdiction of this Technical Committee. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:


(Log #CP41) 91- 37 - (6.1): Accept SUBMITrER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases RECOMMENDATION: Modify the existing 6-1 to read as follows:

6.1" Exhaust systems utilizing combustible components or having the potential for combustible residue build-up on the inside shall be provided with an automatic extinguishing system within the duct and at the duct intake, hood, enclosure or canopy.

Exception No. 1: Ducts with cross-sectional areas less than 75 in.2 (0.0484 m2).

Exception No. 2: Systems constructed of material listed for use without sprinkler protection.

A-6-1 For additional information on these topics, please see the following:

NFPA 11, Standard for Low-Expansion Foam; NFPA l lA, Standard for Medium- and High-Expansion Foam Systems; NFPA 12, Standard on Carbon Dioxide Extinguishing Systems; NFPA 12A, Standard on Haion 1301 Fire Extinguishing Systems; NFPA 12B, Standard on Halon 1211 Fire Extinguishing Systems; NFPA 13, Standard for the Installation of Sprinkler Systems; NFPA 15, Standard for Water Spray Fixed Systems for Fire Protection; NFPA 17, Standard for Dry Chemical Extinguishing Systems; NFPA 17A, Standard for Wet Chemical Extinguishing Systems; and NFPA 2001, Standard on Clean Agent Fire Extinguishing Systems. SUBSTANTIATION: The phrase "or having the potential for combustible residue build-up on the inside" was added to make mandatory a requirement that was previously at the discretion of the authority having jurisdiction.

The term "endosure" was added to more completely address components of the exhaust systems.

The note was deleted and added to the Appendix to comply with the NFPA Manual of Style. COMMITTEE ACTION: Accept. NUMBER OF COMMrlTEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:


EXPLANATION OF NEGATIVE: COLLINS: Committee substantiation indicates that the phrase

"or having the potential for combustible residue build-up on the

inside" was added to make mandatory a requirement that was

~ reviously at the discretion of the authority having jurisdiction. I ave problems with this action. (a) This revision represents an increase in protection

requirements without technical substantiation. Other than the exceptions stated, all ducts require sprinkler protection always. However, all ducts historically have not been equipped with sprinklers or other type of extinguishing protection. While there is a loss record supporting this extinguishing protection, the record does not support the more inclusive proposal.

(b) Conveying systems constructed of materials listed for use without sprinkler protection are inclusive without considering whether or not the material being conveyed represents a hazardous condition sufficient to warrant extinguishing protection. The result of the proposed change to Section 6-1 appears to add additional requirements that serve to be unnecessarily restrictive, and to inclusively exclude extinguishing protection when a hazard exists inside the conveying system.

(Log #CP42) 91- 38 - (6-2): Accept SUBMITTER: Technical Committee on Handling and Conveying of Dusts, Vapors, a n d Gases RECOMMENDATION: Delete the existing 6.2 and corresponding Appendix, and renumber subsequent items. SUBSTANTIATION: Per Committee Proposal 91-37 (Log #CP41), the requirement previously in 6-2 and it's Appendix was included in 6.1 and A-g-l, therefore is redundant. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:


(Log #CP43) 91- 39 - (6-3): Accept SUBMITTER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases RECOMMENDATION: Add a new section 6-3 (note that the existing 6.2 was deleted per Committee Proposal 91-38 (Log #CP42) and the existing 6-3 is now 6-2) to read as follows:

6-3 Fire protection shall be tested and inspected in accordance with the applicable NFPA standards. SUBSTANTIATION: Chapter 7 did not directly address inspection and testing of fire protection systems, and this addition corrects this omission. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITrEE ACTION:

AFFIRMATIVE: 21 NOT RETURNED: 3 Peterson, Underwood, Vaiiulis

(Log #CP44) 91- 40 - (8-1.1): Accept SUBM1TTER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases RECOMMENDATION: In 8-1.1, add NFPA 221, Standard for Fire Wails and Fire Barrier Wails, 1994 edition. SUBSTANTIATION: This standard was referred to in the body of the standard. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITI'EE ACTION:


(Log #CP20) 91- 41 - (Entire Standard): Accept SUBMITTER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases RECOMMENDATION: Throughout the body of the standard, change the term "AMD" to "air moving device". SUBSTANTIATION: The term "AMD" is not readily recognizable. For ease of use, the term should be spelled out.

258

NFPA 9 1 - - F98 ROP

COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:

AFFIRMATIVE: 21 NOT RETURNED: ~ Peterson, Underwood, Valiulis

(Log #CP29) 91- 42 - (Entire Standard): Accept SUBMITI'ER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases RECOMMENDATION: Revise the entire document as shown at

I the end of this Report. SUBSTANTIATION: Due to the combination of previously two Technical Committees, the reconstituted Technical Committee responsible for this document wished to provide every opportunity to individuals to improve the document. In addition, the scope and title were changed, thereby significantly changing the content of the document. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24 VOTE ON COMMITTEE ACTION:


EXPLANATION OF NEGATIVE: NELSON: The standard does not reference or make

requirements for incinerators or thermal oxidizers which are used on flammable liquid systems. It also does not discuss or provide for vapor recovery systems of other types.

NFPA 91

Standard for Exhaust Systems for Air

Conveying of Vapors, Gases, Mists, and Noncombustible Particulate Solids

1999 Edition

NOTICE: An asterisk (*) following the number or letter designating a paragraph indicates explanatory material on that paragraph in Appendtx A.

Information on referenced publications can be found in Chapter 8 and Appendix B.

Chapter 1 Introduction

1-1" Scope.

1-1.1 This standard provides minimum requirements for the design, construction, installation, operation, testing, and maintenance of exhaust systems for air conveying of vapors, gases, mists, and noncombustible particulate solids except as modified or amplified by other applicable NFPA standards.

1-1.2 This s t a o ~ d does not cover exhaust systems for conveying c o m b u s t i b l . . ~ a t e solids. These materials are covered in other N ~ a n d a ~ d s as noted in A-l-1.

1-2 P ~ . o s e ~ e purpose of this standard is to provide technical r eq.~'r~C~ents f g ~ , h a u s t systems that will provide safety to life and

! ~ x p l o s i o n s and t ~ [ j ' o m f u ~ that will minimize the ii Lg~ln the eve~ they occur.

~:~ thing in this standard is intended to p r e v e n t . ~ . x v a l e n c y .

~stems, methods of, or devices of equivalent or superior q ~ strength, fire resistance, effectiveness, durability, and safety o v e i ' ~ f ~ p r e s c r i b e d by this standard, provided that technical docu is submitted to the authority havingjurlsdiction to ~ tion

ate equivalency and that the system, method, or device is ed for the intended purpose.

Retroactivity. The provisions of this document are considered necessary to provide a reasonable level of protection from loss of life and property from fire and explosion. They reflect situations and the state of the art prevalent at the time the standard was issued.

Unless otherwise noted, it is not intended that the provisions of this document be applied to facilities, equipment, structures, or installations that were existing or approved for construction or installation prior to the effective date of the document, except in those cases where it is determined by the authority having

i urisdiction that the existing situation involves a distinct hazard to ife or adjacent property.

1-5 Definitions.

Air-Moving Device.* A power-driven fan, blower, or other device that establishes an airflow by moving a volume of air per unit time.

Approved.* Acceptable to the authority having jurisdiction.

Authority Having Jurisdiction.* The organization, ottice, or individual responsible for approving equipment, an installation, or a procedure.

Duct. Pipes, tubes, or other enclosures used for the purpose of pneumatically conveying materials.

Exhaust System. An air conveying system for moving materials from a source to a point of discharge. A system can consist of an air-moving device with ducting connected either to the inlet or discharge or to both. More complicated systems can include ductwork, an air-moving device, control dampers, a filtration system, noise attenuation, and pollution control equipment.

Labeled. Equipment or materials to which has been attached a label, symbol, or other identifying mark of an organization that is acceptable to the authority having jurisdiction and concerned with product evaluation, that maintains periodic inspection of production of labeled equipment or materials, and by whose

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NFPA 9 1 ~ F98 R O P

labeling the manufacturer indicates compliance with appropriate standards or performance in a specified manner.

Limited-Combustible. A building construction material, not complying with the definition of noncombustible material, that, in the form in which it is used, has a potential heat value not exceeding 3500 Btu/ lb (8141 kJ/kg) where tested in accordance with NFPA 259, Standard Test Method for Potential Heat of Building Materials, and complies with (a) or (b) below• Materials subject to increase in combustibility or flame spread index beyond the limits herein established through the effects of age, moisture, or other atmospheric condition shall be considered combustible•

(a) Materials having a structural base of noncombustible material, with a surfacing not exceeding a thickness of 1 /8 in. (3.2 mm) that has a flame spread index not greater than 50.

(b) Materials, in the form and thickness used, other than as described in (a), having neither a flame spread index greater than 25 nor evidence of continued progressive combustion and of such composition that surfaces that would be exposed by cutting through the material on any plane would have neither a flame spread index greater than 25 nor evidence of continued progressive combustion.

Listed.* Equipment, materials, or services included in a list

~ ublished by an organization that is acceptable to the authority avingjurisdiction and concerned with evaluation of products or

the same exhaust system that air conveys flammable or combustible materials.

2-1.5 Exhaust systems designed to air convey flammable or combustible materials tha t can contain foreign ferrous materials shall have magnetic separators installed at those points where the ferrous materials enter the system. Where electromagnetic separators are used they shall be listed.

2-1.6" Plans and specifications for new systems and systems to be modified shall be submitted to the authority having jurisdiction for approval prior to installation or modification. The submittal shall provide adequate information to describe the hazard and demonstrate safe performance of the system.

2-1.7 Fire dampers, fire stops, and fire interruption devices shall not be instal ledin exhaust systems.

2-1.8 Exhaust ducts shall not pass through fire walls as defined by NFPA 221, Standard for Fire Walls and Fire Barrier Walls.

2-1.9 Ducts that pass through a fire barrier wall having a fire resistance rating of 2 hours or more shall meet the followlng~

(a) Be constructed and supported so that 10 ft (3 m) of the duct on each side of the fire barrier can resist a 2-hour fire scenario

(b) Be protected by sealing the opening around the duct with a listed or approved material of a fire resistance rating equivalent to that of the fire barrier wall

services, that maintains periodic inspection of production of listed 2-1.10 Ducts . ~ p a s s through a fire barrier wall having a fire equipment or materials or periodic evaluation of services, and r e s i s t a n c e . . ~ e s s than 2 hours shall be protected by sealing whose listing states that either the equipment, material, or service the o p e ~ . ~ o u n d the duct with a listed or approved material of meets identified standards or has been tested and found suitable a fire ~ t a~ .~ . / r ax ting equivalent to that of the fire barrier wall. for a specified purpose.

2 ~ e " - ~ a~d alarm systems shall not be interlocked to Noncombustible Material. A material that, in the form in which it ~ m d ~ t ~ ! ~ v i c e s .

is used and under the conditions anticipated, will not ignite, burn, ..~Exce~..jon No. ~ Wh~shutdown is necessary for the effective operation support combustion, or release flammable vapors when subjected .~.~:~..~,., a - n ~ t i ¢ extinguishing system. to fire or heat. Materials reported as passing ASTM E 136, Standard x~ .~,~.~o~.4.~Vo.. 2: A documented risk analysis azceptable to the authon~y Test Method for Behavior of Materials in a Vertical Tube Furnace at 750 Degrees C, shall be considered noncombustible materials, h~t'~'udsdiction shows that the risk of damage from fire and the

~ p r o d ~ m b u s t i o n would be higher with air-moving devices Noncombustible Particulate Solid. Any noncombustible " " " - .

~ h ? ~ i a l n ~ r ~ i ~ p ~ d t s ! ~ d e t ~ r ~ 7 n ~ l ~ p ~ r ~ c ~ . ~ e n s ~ c ~ r c ~ e n u c s ~ i ~ a k . . p q ~ d l e ~ ! ~ ~ a t ~ n a ~ and Construction.

mixtures of these. ' P ' . ~ ~ig ...... 2-2.1 Duct material shall be noncombustible.

• " " "~*:" ' :~" the material bring eonv~ed is incorapatiblo with noncorabnstibl* Shall. Indicates a mandatory reqmrement. / ~ ; . ~ ~ . ~ . , . . ~ i Exception No i: Alternative material shall be permittod to be used when

construction

Y d~':~i~ " - .. Exception No. 2: Listed duct systems that do not require mechanisms

C h a p t e r 2 Design a n ~ ~ . internal to the duct and that have been evaluated ami found to be of lova . ~ ~ ' : ~ . ~ . ~ fire hazard not requiring automatic sprinkler protection to prevent fire

2-1 G e n e r a l Requirements. spread.

2-1.1 The design and installation of ~ t e n k ~ h a l l be the responsibility of persons having a k n o w l e ~ g l ~ s e systems.

2-1.1.1" Incompatible materials shall not be,~ 'hveyed in the same 2-2.2 The duct construction shall conform to the fol lowing applicable Sheet Metal and Air-Conditioning Gontractors 'National system.

2-1.1.2 In systems conveying flammable vapors, gases, or mists, the concentration shall not exceed 25 percent of the lower flammability limit (LFL). Exception: Higher concentrations shall be permitted if the exhaust orstem is designed and protected in accordance with N'FPA 69, Standard

E~Oloslon Prevention Systmns, using one or more of the following techn:ques:

(a) Combustible concentration reduction

(b) Oxidant conczntration reduction

(c) Deflagration suppression

(d) Deflagration pressure containment

2-1.2 The design of any exhaust system shall consider the physical and chemical properties and hazardous characteristics of the materials being conveyed.

2-1.3" An air-moving device shall be sized to confine, capture, and remove, materials. The velocity shall be axlequate to capture matenals and convey them through the exhaust system.

2-1.4 Operations generating flames, sparks, or hot materials, such as from grinding wheels and welding, shall not be consolidated in

Exception No. 3: Plastic duct systems used for handling noncombustible material or flararaable corrosive vapors and that have automatic sprinkler protection as required by Chapter 6.

Association, Inc. (SMACdqA) standards:

(a) Accepted Industry Practice for Industrial Duct Construction

(b) Rectangular Industrial Duct Construction Standard

(c) Round Industrial Duct Construction Standard

(d) Thermoplastic Duct (PVC) Construction Manual

( e) Tlwrmoset FRP Duct Construction Manual

2-2.$ Duct supports shall be designed to carry the weight of the duct system itself plus the anticipated weight of any conveyed materials, ff sprinklerprotect ion is provided inside the duct system, then the duct supports shall also be designed to carry the anticipated weight of any accumulation of sprinkler discharge.

2-2.4 Laps in duct construction shall be in the direction of airflow.

2-2./; Joints in duct construction shall be liquidtight when the conveying system contains condensible vapors or liquids in suspension. Provisions shall be made for drainage of condensate at low points in the duct.

2-2.6 The interior of ducts shall be smooth and joints shall be finished neatly.

260

N F P A 9 1 ~ F 9 8 R O P

2-3 Access.

2-3.1 Access doors shall be provided in horizontal ducts adjacent to elbows, junctions, and vertical ducts. Doors shall be located on the tops or sides of the ducts, and door spacing shall not exceed 12 ft (3.6 m). Exception: Ducts handling materials that do not create a condition requiring access into the duct.

2-3.2 Access doors shall be of the same material and of equal or greater thickness than the duct. Required openings or other penetrations shall be sealed, gasketed, or tightly fitted so that conveyed material will not escape.

2-3.3* Access openings shall be sized to satisfy their intended purpose.

24 Design Requirements.

2-4.1 A means shall be provided for balancing the system.

2-4.2 Dampers or shutters shall be permitted only for weather or back-draft protection. Where dampers or louvers are used, they shall be located on the clean-air side of the filtration system.

2-4.3 Balancing devices shall be secured to prevent inadvertent adjustment or loss of transport velocity. Butterfly dampers shall not be permitted for balancing duct systems conveying solid materials.

2-4.4 Ducts shall be self-contained. Building walls, floors, or roofs shall not be used as component parts.

Exception: Use of building walls, floors, or roofs shall be permitted when construction is noncombustible and the building component is designed as an integral part of the duct system.

2-4.5 Ducts shall lead directly to the point of termination.

2-4.5.1" Terminations with discharge to the atmosphere shall be safely arranged.

2-4.6* Materials shall be confined to and removed from the area where they are generated by hoods or enclosures and an air- moving d e v i c e . . . ~ , a ~ Exception: When vapors are generated and it is not possible for the process to be enclosed or hoods installed, general ventilation through system of suction ducts shall be permitted.

2-4.7* Vapors containing residues or n o n c o m b n s t i J ~ u l a t e solids shal l be filtered. ~ ~ ~ ~ - : ~ V

2-4.8 Duct liners that are combustible shall m following requirements:

irifi (a) Liners tested as part of a listed d t ~ ~ a t ~ n

evaluated and found to be of low f i r e ~ d n~if~'~u i ~ " automatic sprinkler protection to ~ f i r e s p r ] ~ .~

(b) Liners used for handling n o n c o ' F ~ t i b l e m ~ r i a l or flammable corrosive vapors and that hav~kli~ma~gt~'sprinkler protection as required by Chapter 6 " ~ - ~ "

2-4.9 Additional branch ducts shall not be added to an existing system without redesigning the system. Branch ducts shall not be disconnected nor unused portions of the system be blanked off without providing means to maintain required airflow.

2-4.10 Flexible ducts shall not be used in exhaust systems. Exception." Flexible ducts shall be permitted to be used at inlets where rnoveabili 0 or portabili 0 is required. Where used, thsy shall have strength equivalent to that of the connecting ducts.

2-5 Hangers and Supports.

2-5.1 Duct supports shall be designed to carry the weight of the duct half filled with material. Where sprinkler protection is provided in the duct, the hanger 's design shall include the weight of the duct half filled with water or with the material being conveyed, whichever has the highest density. Loads shall not be placed on connecting equipment. Exception: Where adequate drainage is provided, the weight of the water shall not require consideration.

2-5.2 Hangers and supports exposed to corrosive atmospheres shall be type 316 SS or equivalent.

2-5.3 Hangers and supports shall be securely fastened to the building or structure to avoid vibration and stress on the duct.

2-5.4 Hangers and supports shall be designed to allow for expansion and contraction.

2-6 Duct C l ~ e s .

2-6.1

No. 1: V automatic

To. 2: f nta~ with

rk and system components handling combustible gating at less than 140°F (60°C) shall have a

than 18 in. (46 on) from combustible ~ . ~ t b n s t i b l e material. W ~ the ductwork system is equipped with an ~c "gxtinguishing system designed for the specij~ ~ce shall be permitted to be reduced to 6 in. (15 cra) ,~teriale and 1 /2 in. (13 tara)from combustible

The combustible material and construction is protected ~als or products listed for protection purposes or in gble 2-6.1.

2-6.1.1 Spacers and ties for protection materials shall be of noncombustible material and shall not be used directly behind the duct.

2-6.1.2 With all clearance reduction systems using a ventilated air space, air circulation shall be provided as described in 2-6.4. There shall be at least 1 in. (2.5 on) between the wall protector and combustible walls and ceilings for clearance reduction systems using a ventilated space.

Table 2-6.1 of Duct Clearance with Specified Forms of Protection Clearance reduction applied to and covering all combustible surfaces within the distance specified as required clearance with no protection in 2-6.2 and Table 2-6.3

Form of Protection (a) 31/z-in. (90-mm) thick masonry wall without ventilated air space (b) l/~-in. (13-ram) thick noncombustible insulation board over 1-in. (25.4-mm) glass fiber or mineral wool batts without ventilated air space (c) 0.024 in. (0.61 ram) (24 gauge) sheet metal over loin. (25.4.mm) glass fiber or mineral wool balls reinforced with wire, or equivalent, on rear face with at least a 1-in. (25.4-mm) air gap (d) 31/2-in. (OO-mm) thick masonry wall with at least a 1-in. (25.4- nun) air gap (e) 0.024 in. (0.61 mm) (24 gauge) sheet metal with at least a bin. (25.4-mm) air gap (f) 1/2-in. (l$-mm) thick noncombustible insulation board with at least a 1-in. (25.4-mm) air gap (g) 0.024 in. (0.61 mm) (24 gauge) sheet metal with ventilated air space over 0.024 in. (0.61 mm) (24 gauge) sheet metal with at least a 1-in. (25.4-mm) air gap (h) 1-in. (25.4-mm) glass fiber or mineral wool batts sandwiched between two sheets 0.024 in. (0.61 mm) (24 gauge) sheet metal with at least a 1-in. (25.4-mm I air [~ap

Maximum allowable reduction in clearance (percent)

As Wall Protector As Ceiling Protector 33% 50% ss%

66% 66%

66%

66% 50%

66% 50%

66% 50%

66% 50%

261

NFPA 91- - F98 ROP

2-6.1.3 Mineral wool batts (blanket or board) shall have a minimum density of 8 lb per ft 3 (3.6 kg/m 3) and have a minimum melting point of 1500°F (816°C).

2-6.1.4 Insulation board used as a part of a clearance reduction system shall have a thermal conductivity of 1 Btu-in./ft2-hr-°F (0.14 W/m2-hr-°C) or less. Insulation board shall be formed of noncombustible material.

2-6.1.5 There shall be at least 1 in. (2.5 cm) between the duct and the wall protector. In no case shall the clearance between the duct and the wall surface be reduced below that shown in the Table 2- 6.1.

2-6.2 Duct systems operating at elevated temperatures above 140°F (60°C) shall have clearances from combustible building construction or any combustible material of not less than 18 in. (46 cm).

2-6.3 Where clearance is reduced by using an air space between the combustible wall and the wall protector, air circulation shall be provided by one of the following methods.

2-6.3.1 Air circulation shall be permitted to be provided by leaving all edges of the wall protector open with at least a 1-in. (2.5-cm) air gap.

2-6.3.2 ff the wall protector is mounted on a single flat wall away from comers, air circulation shall be permitted to be provided by one of the following:

(a) Leaving top and bottom edges open to circulation by maintaining the 1-in. (2.5-cm) air gap

(b) Leaving top and both side edges open to circulation maintaining the 1-in. (2.5-cm) air gap

2-6.$.$ Wall protectors that cover two walls in a corner shall be permitted to be open at the top and bottom edges with at least a l- m. (2.5-cm) air gap.

2-6.4 All clearances shall be measured from the outer surface of the combustible material to the nearest point on the outer surf~ of the duct, disregarding any intervening protection applied to'~. combustible material. Clearances shall be measured as shown 1 c~cUre 2-6.4. Clearances with protection provided shall be

ulated by using the equation as shown as dimension B in Figure 2-6.4. . ~

"l-R" "~ ::<#

.... ~ % ~ i~.:: .~

..<$ <-~-:~:~:

~ , clearffgc~ : t i ~ minimum allowable :_ P ~ P ~ protec required clearance with no ~: = maximum allowed r e d u c t i o n r ° ~ c e i n c ~*:"

Construction using combustible material " ~

N N

Sheet metal or other protection

Duct

Duct

Construction using ~ ,.,. Sheet metal or combustible material " ~ ] other protection

r ~ ' a r a n c e with no ,protection. ; .#t:learance permitted. flied to the construction using combustible material ough in each direction to make C equal to A.

Extent of protection required to reduce clearances from ducts.

Chapter $ Corrosive Materials

3-1 General. Exhaust systems utilizin~ plastic material shall be permitted to be used to convey corroswes. The choice of the material type shall be the responsibility of the design engineer. All chemical-resistantplastics have heat limitations that shall be considered when designing a system. The following minimum standards of materials, construction, and workmanship shall be deemed necessary to ensure minimum fire hazard in the operation of these systems.

3-1.1 Plastic ducts shall be in accordance with 2-2.1 and 2-4.8. All hoods and air-moving device surfaces that are part of the system shall have flame spread ratings at least equivalent to the flame spread rating of the material of the duct system.

3-1.2 Plastic duct materials shall be listed with an external smoke development rating of 50 or less when located in a multistory building or a concealed space. Exception No. I: Duct systems that are located in an area protected by an automatic sprinkler system.

Exception No. 2: Duct systems that are located in a 1-hour fire-rated enclosu~'e.

Chapter 4 Air Moving Devices 4-1 Air moving devices shall be constructed of noncombustible materials and shall be designed and installed to convey materials through the exhaust system safely.

Exception: Where the materials conveyed are not compatible with metals, alternate materials of construction shall be permitted.

4-2 Where the materials conveyed are flammable or combustible, the rotating element of the air-moving device shall be nonferrous, or the air-moving device shall be constructed so that a shift of the rotating element or shaft does not permit two ferrous parts to rub or strike.

262

NFPA 9 1 ~ F98 ROP

48 Clearance between the rotating element and the fan casing shall be provided to avoid friction that might lead to fire. Allowances shall be made for expansion and loading to prevent contact between moving parts and the duct or fan housing.

4-4 Fan rotating elements shall be mounted on a shaft designed to maintain proper alignment even when the blades or impeller are loaded.

4-5 Motors, bearings, drive components, and electrical equipment shall not be placed inside ducts unless they are protected or enclosed to prevent ignition of flammable vapors, mists, residues, dusts, or other combustible materials that are conveyed in the exhaust system.

4-6 Air-moving devices shall be located to permit ready access for inspection, lubrication, maintenance, cleaning, and repair. They shall be placed on proper foundations or firmly secured to proper supports.

4-7 Air-moving devices used in systems that air convey dust or vapors containing residue shall be located on the clean-air side of the filtration system.

4-8 Flexible connections shall be permitted in order to minimize the transmission of vibration.

Chapter 5 Ignition Sources

5-1 Electrical Equipment. All electrical equipment and installations shall coml?y with the requirements of NFPA 70, National Electrical Code ~.

5-2* Static Electricity.

5-2.1" All system components shall be conductive. Bonding and grounding with a resistance of less than 1.0 x 106 ohms to ground shall he provided. Exception: Nonconductive equipment shall be permitted to be used as covered in this document by Chapter 3. 5-2.2 Where belt drives are used, the belts shall be electrically " . ~ conductive at 1 megohm or less. ~ i TM

5-3 Manifolds. Operations generating flames, sparks, or hot ~A material such as from grinding wheels and weid 'n~ .~ ' . ,~ .~ t be ~.~ manifolded into any exhaust system that handies I: or combustible materials. ~ ~ - - ~ ~ . ~ ~ ~ i . . ~ " '~'

5-4 Open Flames and Sparks, The requirements 5-4.3 shall be applied retroactively . . . . . .

Cutting andweldingshal, requirements ofNFPA51B, Standa~o~ffire P r ~ t ~ s f of Cutting and Welding Processes. .~

" ns th 5-4.2 Grinding, chipping, and other o either sparks or open flame ignition sou controlled by a hot work permit system in accordance wi , 51B, Standard for Fire Prevention in Use of Curing and Weld ~Processes. 5-4.$ Smoking shall be permitted only in designated areas.

5-5 Removal of Ferrous Materials. Ferrous materials capable of igniting combustible material being conveyed shall be removed from the exhaust stream by magnetic separators of the permanent or electromagnetic type. Where electromagnetic separators are used, provisions shall be made to indicate the loss of power to the electromagnetic separators.

, 5-6 Belt Drives. Belt drives shall be designed to stall without the belt slipping, or a safety device shall be provided to shut down the equipment if slippage occurs.

5-7* Bearings. Roller or ball bearings shall be used on all processing and transfer equipment. Lubrication shall be performed in accordance with the manufacturer's recommendations. Exception: Bushings shall be permitted to be used when an engineering evaluation shows that mechanical loads and speeds preclude ignition due to frictional heating.

Equipment. Equipment with moving parts shall be installed and maintained so that true alignment is maintained and clearance is provided to minimize friction.

Chapter 6 l~re Protection

6-1" Exhaust systems utilizing combustible components or having the potential for combustible residue buildup on the inside shall be provided with an automatic extinguishing system within the duct and at the duct intake, hood, enclosure, or canopy.

Exception No. 1: Ducts with cross-sectional areas less than 75 in. 2 (0.0484 m2). Exception No. 2: Systems constructed of material listed for use without sprinkler protection. 6-2 When a sprinkler system is installed, means shall be provided to prevent water accumulation in the duct or flow of water back to a process subject to damage by water.

6-3 Fire protection shall be tested and inspected in accordance with the applicable NFPA standards.

Chapter 7 Testing and Maintenance 7-1 Exhaust systems shall be tested, inspected, and maintained to ensure safe operating conditions.

7-1.1 The responsibility for proper maintenance shall be assigned to trained personnel who are capable of recognizing potential hazards.

7-1.2 Such ~ a n c e shall include the determination that special p r ~ t i o r i " f t r duct systems is fully operable and that plant a u t o m a . ~ k l e r protection is in service.

7 * don of new systems is complete the system shaii b . ~ . ~ , et d t~ .¢ . '~o .o~trate performance before acceptance by

sting systen~g shall be tested periodically by the owner to ~ t e continued performance.

system components shall be inspected monthly. . . . 1: Where manufacturer's requirements are more stringent. "~'~Noi 2: Where conditions of service dictate more frequent

~.~'..- 1 Ade. qui te maintenance of air-conveyin, lgsy~systems requires. periodic inspection of the duct, fitangs, hardware, filtration system, and air-moving devices.

74 .2 This inspection shall include the hoods, enclosures, air inlets, ducts, and access doors through the termination of the system. It shall include the termination, adjacent surfaces, and any adjacent air intakes.

7-4.$ The user's operational and maintenance program shall include all of the manufacturer 's listed procedures that are applicable to the equipment.

7-4.4 An operational and maintenance checklist shall be maintained and is essential to safe operation of the equipment.

7-4.5 Accumulations of conveyed materials and residues shall be removed from hoods and endosures, ducts and fittings, and air- moving devices. The ducts shall be checked for obstructions such as improperly adjusted dampers or shutters. Filtration systems shall be inspected and filters cleaned or replaced as required.

7-4.6 Air-moving devices shall be inspected for belt tension and wear and lubrication.

7-4.7 Hoods and enclosures shall be inspected for proper confinement and removal of materials.

7-5 Ductwork shall be examined periodically to determine adequacy of cleaning frequency.

7-6 All system components shall be maintained in good operating condition. A written maintenance program shall be established. The program shall include any and all recommendations provided by the manufacturer.

All deficiencies found during testing and inspection shall be corrected. Serious deficiencies shall require immediate attention.

7-7 An operational maintenance log shall be maintained to document maintenance actions.

263

NFPA 9 1 ~ F98 ROP

Chapter 8 Referenced Publications

8-1 The following documents or portions thereof are referenced within this standard as mandatory requirements and shall be considered part of the requirements of this standard. The edition indicated for each referenced mandatory document is the current edition as of the date of the NFPA issuance of this standard. Some of these mandatory documents might also be referenced in this standard for specific informational purposes and, therefore, are also listed in Appendix B.

8-1.1 NFPA Publications. National Fire Protection Assodation, 1 Batterymarch Park, P.O. Box 9101, Quincy, MA 02269-9101.

NFPA 51B, Standard for Fire Prevention in Use of Cutting and Welding Processes, 1994 edition.

NFPA 69, Standard on Explosion Prevention Systems, 1997 edition. NFPA 70, National Electrical Code s, 1996 edition. NFPA 221, Standard for Fire Walls and Fire Barrier Walls, 1997

edition. NFPA 259, Standard Test Method for Potential Heat of Building

Materials, 1998 edition.

8-1.2 Other Publications.

8-1.2.1 ASTM Publication. American Society for Testing and Materials, 100 Barr Harbor Drive, West Conshohocken, PA 19428- 2959.

ASTM E 136, Standard Test Method for Behavior of Materials in a Vertical Tube Furnace at 750 Degrees C, 1993.

8-1.2.2 SMACNA Publications. Sheet Metal and Air-Conditioning Contractors' National Association, Inc., 4201 Iafayette Center Drive, Chantilly, VA 22021.

A~epted Industr 3 Practice for Industrial Duct Construction, 1975. Rectangular Industrial Duet Construction Standard, 1980. Round Industrial Duct Construction Standard, 1977. Thermoplastic Duct (PVC) Construction Manual, 2nd edition, 1 ~ Thermoset FRP Duct Construction Manual, 1977. ~

Appendix A Explanatory Mate~'~ £ ~ < x . . . ~ ~:. ~.~.

Appendix A is not a part of the requirements of__~i.s but is indudod for informational p u r p o s e s . o . . ~ ~co~Atai~.

materia~ numbered to ~ ~ t ~ . i di~ e,,gtauator ~ bered to corres~ . . ., paragraphs. ~ : .

A-I-I The following NFPA s t a n d a f i l s ~ i n infor tlon on the application of exhaust systems to ~ u s speci tile r operations.

NFPA 30, Flammable and Combustible~..4Liq~ ~.,e&,~.~ NFPA 30B, Code for the Manufacture and 6 ; ~ e of Aerosol

Products "~ NFPA 32, Standard for Drydeaning Plants NFPA 33, Standard for Spray Application Using Flammable and

Combustible Materials NFPA 34, Standard for Dipping and Coating Processes Using

Flammable or Combustible Liquids NFPA 35, Standard for the Manufacture of Organic Coatings NFPA 36, Standard for Solvent Extraction Plants NFPA 45, Standard on Fire Protection for Laboratories Using

Chemicals NFPA 46, Recommended Safe Practice for Storage of Forest Products NFPA 61, Standard for the Prevention of Fires and Dust Explosions

in Agricultural and Food Products Fadlities NFPA 65, Standard for the Processing and Finishing of Aluminum NFPA 68, Guide for Venting of Deflagrations NFPA 86, Standard for Ovens and Furnaces NFPA 86C, Standard for Industrial Furrmees Using a Special

Processing Atmosphere NFPA 86D, Standard for Industrial Furnaces Using Vacuum as an

Atmosphere

NFPA 88B, Standard for Repair Garages NF~A 92A, Recommended Practice for Smoke-Control Systems NFPA 92B, Guide for Smoke Management Systems in Malls, Atria,

and Large Areas NFPA 96, Standard for Ventilation Control and Fire Protection of

Commercial Cooking Operations NFPA 120, Standard for Coal Preparation Plants NFPA 204M, Guide for Smoke and Heat Venting NFPA211, Standard for Chimneys, Fireplaces, Vents, and Solid Fuel-

Burning Appliances NFPA 303, Fire Protection Standard for Marinas and Boa~yards NFPA 318, Standard for the Protection of C/eanrooms NFPA 409, Standard on Aircraft Hangars NFPA 480, Standard for the Storag6 Handling, and Processing of

Magnesium Solids and Powders NFPA 481, Standard for the Production, Processing, Handling, and

Storage of Titanium NFPA 650, Standard for Pneumatic Conveying Systems for Handling

Combustible Materials NFPA 651, Standard for the Manufacture of Aluminum Powder NFPA 654, Standard for the Prevention of Fire and Dust Explosions

from the Manufacturing, Processing, and Handling of Combustible Particulate Solidy.

NFPA 6 5 . ~ . ~ r d for Prevention of Sulfur Fires and Explosions NFPA?A,~,x2~:~" ' Sta~ard for the Prevention of Fires and Explosions in

Wood P...4~es'~and Woodworking Facilities ~ O l , ~ ¢ g l a r d far Fire Protection for Fadlities Handling

Device. An air moving device is a fan, , or mixed-flow fan. These devices have previously

1 ed blowers or exhausters.

~r~ovetL The National Fire Protection Association A-1-5 "~ , does 4" "ove, ~ a ~ inspect, or certify any installations, proceaures,

~ m e n t , or materials; nor does it approve or evaluate testing l ~ r , l ratories. In . . . . determining the acCeHetability of installations, procedures, eqmpment, or materials, authorRy having jurisdiction may base acceptance on compliance with NFPA or other appropriate standards. In the absence of such standards, said authority may require evidence of proper installation, procedure, or use. The authority having jurisdiction may also refer to the listings or labeling practices of an organization that is concerned with product evaluations and is thus in a position to determine compliance with appropriate standards for the current production of listed items.

A-1-5 Authority Having Jurisdiction. The phrase "authority having jurisdiction" is used in NFPA documents in a broad manner, since jurisdictions and approval agencies vary, as do their responsibilities. Where public safety is primary, the authority having jurisdiction may be a federal, state, local, or other regional department or individual such as a fire chief; fire marshal; chief of a tire prevention bureau, labor department, or health department; building official; electrical inspector; or others having statutory authority. For insurance purposes, an insurance inspection department, rating bureau, or other insurance company representative may be the authority having jurisdiction. In many circumstances, the property owner or his or her designated agent assumes the role o f the authority having jurisdiction; at government installations, the commanding officer or departmental official may be the authority having jurisdiction.

A-I-5 Listed. The means for identifying listed equipment may vary for each organization concerned with product evaluation; some organizations do not recognize equipment as listed unless it is also labeled. The authority havingjurlsdlction should utilize the system employed by the listing organization to identify a listed product.

A-2-1.1.1 Materials when mixed should not create a fire, explosion, or health hazard.

A-2-1.3 Capture, control, and conveying of materials is achieved by inward air flow generated by the exhaust pickup or intake, the intake velocity, and the duct velocity.

Capture velocities must be high enough to maintain control of the material:

264

NFPA 91- - F98 ROP

(a) Until it reaches the intake open ing

(b) To overcome thermal air currents f rom hot processes or heat-generat ing operations

(c) To overcome air currents caused by gr inding wheels and belt conveyors

(d) To overcome air currents caused by dumping and filling operat ions

Exhaust systems des igned for gases, vapors, fumes, and fine dust particles (20 microns or less) require intake velocities high enough to offset air currents caused by room cross drafts.

Duct velocities are de te rmined by the type of material conveyed (see Table A-2-1.3).

Fundamentals Handbook, the "Airflow Around Buildings" chapter or the ACGIH publicat ion Industrial Ventilation - - a Manual of Recommended Practice Ventilation Manual

A-2-4.6 Control at the point of generat ion should be provided in any vapor-conveying system. Control is provided by hoods or enclosures connec ted to suction ducts. These can confine vapors and, in most cases, will do this with lower air volume.

When the vapors cannot be readily picked up at the source, general ventilation through a system of suction ducts can be used. The suction inlets have little directional effect beyond a few inches from the inlet; they should be located to sweep the air and minimize pockets with no air movement• The location of the air make-up system ductwork and discharge points will provide more uniform air movement .

Nature of Contaminant Vapors, gases, smoke

Fumes Very fine light dust Dry dusts and powders

Table A-2-1.3 Range of Minimum Duct Desiffn Velocit ies

Average industrial dust

Examples All vapors, gases, and smoke

Welding Cotton lint, wood flour, litho powder Fine rubber dust, Bakelite molding powder dust, ju te lint, cotton dust, shavings (light), soap dust, leather shavings Grinding dust, buffing lint (dry), wool ju te

Desil~n Velocit~ Any desired velocity (economic op t imum velocity

usually 1000-2000 fpm) (305-610 m / m i n ) 2000-2500 fpm (610-763 m / m i n ) 2500-3000 fpm (763-915 m / m i n )

3000-4000 fpm (915-1220 m / m i n )

5500-4000 fpm (1068-1220 m/ ra in ) dust (shaker waste), coffee beans, shoe dust . . . . ~:. l~ranite dust, silica flour, general material ~ . ~ laandling, brick cuttincr, clay dust foundry .~" ~"~:'~ • '. ~..'~#2.:. (general), hmestone ~'ust, packaging and .,~.~.'.,s.'.j~;.E~):~... weighing asbestos dust in textile i n d u s t t t ~ : "%i~!~

Heavy dusts Sawdust (heavy and wet), metal t u r n i n ~ : ~ xff~...-'.%~ 4000--4500 fpm (1220-1373 m/ra in ) • .:.-: ?~: " + . ' . : : .- .~.. . . .

foundry tumbhng barrels and s h a k ~ "%-'..'~.,........$~ blast dust, wood blocks, hog wask~:~o .ross ''" . . . . ~i~ff "~ turnings, cast i ron boring d u s t ~ . d d ~ . . . ~'.-".'~:"

Heavy or moist Lead dusts with small chips, ~ ~ . . . : : . 4500 fpm and up (1373 and up m / m i n ) dust, asbestos chunks from t r a n s i t ~ f i ~ . . . . . :~ cutting machines, buffing lint ( s t i c l ( ~ i c k - . . lime dust 4.~.-..::,~. ~'~:. , :~

Source: Industrial Ventilation - - a Manual of Recommended Pract;~.,:~;. ~'i~/~"......~,:....*.~i~.::.~. ~ f e r e n c e of Governmental Industrial Hygienists.

. . . . ~!.:":~"':%ii!i~ ":!i:::: . When vapors are heavier than air or vapors and residues are The des~ her also must constder suck or wet ~dues ~ • g Y .:.::~ :-~ . ::.-':ii~+:: mixed, inlets located near the floor should be considered. When

parucles, electrostatic effects, and so forth. .:~¢~"::~iiiiiiiii::. ~:-~:..~i~.-::,. "%:i U~ the vapors are lighter than air, the inlets should be located near For fur ther information, refer to Industrial V e n t i : ~ a":~':.~.:.:!i~!i ~i the ceiling of the room or enclosure.

Manual of Recommended Practice, published..~..-.*~.¢ Am'~¢ '~ l • • • . . . . . . . . . . ~;~:::.:.:.:::::-:-.-.~:..-.. .:.:.:.:-:.:. ~. A-2-4.7 Methods of f i l tenn~ include o ther means bestdes cloth or t~omerence oI t .overnmental l n ( l u s t r l a ~ : : l - l y g l ~ . - : : : : : : : : : : : : : : : : : : : : : : : ~ • • . ~" ~.?-'~:: ":*~::-:i:~:':-" paper-type filters• Examoles of filtrauon dewces include, but are A-2-1.6 The design of the exhaust sy~. '~ s h o u l d ' ~ i ~ o r c l j ~ ' t e d n o i lirdi~ed to, disposable or cleanable filters, scrubbers, cyclones, with.the .architectural.and s t r n c t u ~ { " : ~ , s. The ~ s and dust collectors, or reduct ion of t ransport velocity. s ecificat~ous should mclude a hst of ~I~ Ul men m u g p . . . . . i i ~ l i p ~gi~ " . . A-5-2 See NFPA 77 Recommended Practice on Static Electricity, for manulacturer and type numoer , arm sno~l.g.:~:Naow , . ~ ctata listed information on this subiect. below. Plans should be drawn to an indica~:~.~.#|~ and show all essential details as to location, construction, ~ ' t i l a t i o n ductwork, A-5-2.1 Bonding minimizes the potential difference between volume of outside air at s tandard tempecatm'iff and pressure conductive objects. Grounding minimizes the potential difference in t roduced for safety ventilation, and control wiring diagrams. The details of the plan should include the following:

(a) Name of owner and occupant

(b) Location, including street address

(c) Point of compass

(d) Ceiling construction

(e) Full height cross-section

(f) Location of fire walls

(g) Location of partitions

(h) Materials of duct construct ion

A-2-3.3 Access into ducts is required to perform in tended inspection, to clean interior surfaces, and to service or replace devices located inside the duct.

A-2-4.5.1 Discharge should terminate away f rom outside air intakes to prevent material f rom enter ing the air intakes. For duct systems containing f lammable or combustible materials, an evaluation is necessary to de te rmine adequate exhaust stack termination design. Information on stack height can be found in the ASHRAE, 1997

between objects and ground. Using metal ducts with nonconduct ive plastic liners to convey

mists and particulate solids can create a propagat ing brush discharge ignition or shock or both.

A-5.6 Transmission of power by direct drive should be used where possible in preference to belt or chain drives•

A-5-7 Consideration should be given to the potential for overheating caused by dust entry into bearings. Bearings should be located outside the exhaust stream where they are less exposed and more accessible for inspection and service. Where bearings are in contact with particulate solid streams, sealed or purged bearings are preferred.

A-6.1 For additional information on these topics, please see the following:

NFPA 11, Standard for Low-Expansion Foam; NFPA l l A , Standard for Medium- and High-Expansion Foam systems; NFPA 12, Standard o n Carbon Dioxide Extinguishing System~, NFPA 12A., Standard on Halon 1301 Fire Extinguishing Systems; NFPA 13, Standard for t h e InstaUation of sprinkler System~, NFPA 15, Standard for Water Spray Fixed Systems for Fire Protection; NFPA 17, Standard for D O Chemical Extinguishing S ystem~, NFPA 17A, Standard for Wet Chemical Extinguishing .~iystems;, and NFPA 2001, Standard o n Clean Agent Fire Extinguishing Systems.

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NFPA 9 1 - - F98 R O P

A-7-2 Initial Test. The following outlines the required procedure and the minimum data necessary for a thorough initial ventilation test:

(a) Review the system specifications and drawings to determine the relative location and sizes of ducts, fittings, and associated system components.

(b) Inspect the system to determine that its installation is in accordance with the specifications and drawings. Check such items as fan rotation, belt slippage, damper settings, and thermal overload sizes of starters.

(c) Make a single-line drawing of the installed system and select and identify test locations.

(d) Measure the air volume, fan static pressure, motor rpm and amperes, and the temperature of the air in the system. Also, determine pressure drops across all components (such as air cleaning equipment).

(e) Record the test data and design specifications.

(f) Compare the test data with design specifications and determine if alterations or adjustments of the system are necessary to meet specifications.

(g) If alterations or adjustments are made, retest the system and record the final test data, noting any physical changes that were made on the sketch.

(h) Provide a permanent label indicating fan data - - static pressures, rpm, and motor current.

(i) Lock all dampers and mark positions with permanent marker.

(j) Owner must retain test data sheets for the life of the system.

Field Test. The tests described pertain to air-handling characteristics only. At times it might be necessary or desirable to conduct tests of the environment to determine whether the system is providing the desired environmental control. In these c a s e s , ~ . services of a trained industrial hygienist might be required.

For some tests, moisture content of the air in the system or th ambient barometric pressure should also be obtained.

All periodic measurements can also be made cL_.~ ~ l y by means of an operating console or other remote. ,~

The value of obtaining ventilation test data ~ ~ " * following applications: :,. ~ ' - ' ~

(a) To record the initial p e r f o r m ~ ~ . e n ~ . : . determine if it is functioning in acco.l'~ance w i ~ c a . . , ~

(b) To determine the degree -~ '~"~ l . i ance wi~'~ l~ ~':able codes or trade association standards "~'~i~.~'. i!.~

(c) To provide data upon which to has ~ . ~ e s s a r y changes in the system ~ , : : ' - ~

. .::i:: ~

(d) To obtain data to assist in the design ~f future systems

(e) To determine whether the system has sufficient capacity for additional ductwork or other alterations

(f) To obtain data through periodic checks to determine when maintenance or repairs are necessary

A-7-$ The following is the required procedure for measurements needed to perform the periodic tests:

(a) Refer to the initial test data sheet for test locations.

(b) Inspect the system for physical damage (broken, corroded, collapsed duct, and so forth) and proper operation of components (fan rotation, damper positions, air cleaner condition, and so forth).

(c) Measure static pressure at the same locations used in the initial test.

(d) Compare measured static pressure at the same locations used in the initial test.

(e) Make and record any corrections required.

(f) Recheck the system to verify performance if corrections have been made.

A-7-4 Inspection should include hoods; enclosures; ducts; duct connections; filtration system; blast gates locked in marked positions; access openings closed and secured; air moving device inlets and outlets; air-moving device for belt tension, vibration, and lubrication; and termination and adjacent surfaces.

Appendix B Referenced Publications

B-1 The following documents or portions thereof are referenced within this standard for informational purposes only and are thus not considered part of the requirements of this standard unless also listed in Chapter 8. The edition indicated here for each reference is the current edition as of the date of the NFPA issuance of this standard.

B-I.I NFPA Publications. National Fire Protection Association, 1 Batterymarch Park, P.O. Box 9101, Quincy, MA 02269-9101.

NFPA 11, Standard for l.,ma-Expansion Foam, 1998 edition. NFPA l lA , Standard for Medium- and High-Expansion Foam

Systems, 1994 edition. NFPA 12, Standard on Carbon Dioxide Extinguishing Systems, 1998

edition. NFPA 12A, Standard on Halon 1301 Fire Extinguishing Systems,

1997 edition. NFPA l $ . , ~ r d for the Installation of Sprinkler Systems, 1996

edition. ~ " N F ~ x ~ l ~ a r d for Water Spray Fixed Systems for Fire

r Dry ~ q , S t a ~ Chemical Extinguishing Systems, 1998

Sta ~ ~ . ~ . ~ . 17A, rd for Wet Chemical Extinguishing Systems, 1998

~ 0 , Flammable and Combustible Liquids Code, 1996 edition.

N F ~ B , Code for the Manufacture and Storage of Aerosol Produ, ~z'1994 edition.

A32, Standard for Drycleaning Plants, 1996 edition. ?PA 33, Standard for Spra~ Application Using Flammable and

ombustible Materials, 1995 edition. NFPA 34, Standard for Dipping and Coating Processes Using

Flammable or Combustible Liqmds, 1995 edition.

NFPA 35, Standard for the Manufacture of Organic Coatings, 1995 edition.

NFPA 36, Standard for Solvent Extraction Plants, 1997 edition. NFPA 45, Standard on Fire Protection for Laboratories Using

Chemicals, 1996 edition. NFPA 46, Recommended Safe Practice for Storage of Forest Products,

1996 edition. NFPA 61, Standard for the Prevention of Fires and Dust Explosions

in Agricultural and Food Products Facilities, 1995 edition. NFPA 65, Standard for the Processing and Finishing of Aluminum,

1993 edition. NFPA 68, Guide for Venting of Deflagrations, 1994 edition. NFPA 77, Recommended Practice on Static Electricity, 1995 edition. NFPA 86, Standard for Ovens and Furnaces, 1995 edition. NFPA 86C, Standard for Industrial Furnaces Using a Special

Processing Atmosphere, 1995 edition. NFPA 86D, Standard for Industrial Furnaces Using Vacuum as an

Atmosphere, 1995 edition. NFPA 88B, Standard for Repair Garages, 1997 edition. NFPA 92A, Recommended Practice for Smoke-control Systems, 1996

edition.

NFPA 92B, Guide for Smoke Management Systems in Malls, Atria, and Large Arms, 1995 edition.

NFPA 96, Standard for Ventilation Control and Fire Protection of Commercial Cooking Operations, 1994 edition.

NFPA 120, Standard for Coal Preparation Plants, 1994 edition. NFPA 204M, Guid~ for Smoke and Heat Ventln~ 1991 edition.

266

N F P A 9 1 / 6 5 5 - - F98 R O P

NFPA 211, Standard for Chimneys, Fireplaces, Vents, and Solid Fuel- Burning Appliances, 1996 edition.

NFPA 303, Fire Protection Standard for Marinas and Boa~ards, 1995 edition.

NFPA 318, Standard for the Protection of Cleanrooms, 1995 edition.

NFPA 409, Standard on Aircraft Hangars, 1995 edition. NFPA 480, Standard for the Storag6 Handling, and Processing of

Magnesium Solids and Powders, 1995 edition. NFPA 481, Standard for the Production, Processing, Handling, and

Storage of Titanium, 1995edition. NFPA 650, Standard for Pneumatic Conveying Systems for Handling

Combustible Materials, 1998 edition. NFPA 651, Standard for the Manufacture of Aluminum Powder,

1993 edition. NFPA 654, Standard for the Prevention of Fire and Dust Explosions

from the Manufacturing, Processing, and Handling of Combustible Particulate Solids, 1997edition.

NFPA 655, Standard for Prevention of Sulfur Fires and Explosions, 1993 edition.

NFPA 664, Standard for the Prevention of Fires and Explosions in Wood Processing and Woodworking Facilities, 1993 edition.

NFPA 801, Standard for Fire Protection for Facilities Handling Radioactive Materials, 1998 edition.

NFPA 2001, Standard on Clean Agent Fire Extinguishing Systems, 1996 edition.

NFPA 8501, Standard for Single Burner Boiler Operation, 1997 edition.

B-I.2 ACGIH Publication. American Conference of Governmental Industrial Hygienists, Kemper Woods Center, 1330 Kemper Meadow Drive, Cincinnati, OH 45240.

Industrial Ventilation - - a Manual of Recommended Practice, 21st edition, 1992.

B-I.3 ASHRAE Publication. American Society of Heating, Regrigerating and Air ConditioningEngineers, Inc., 1791 Tullie Circle, N.E., Atlanta, GA 30329-2305.

ASHRAE 1997 Fundamentals Handbook.

PART II

(Log #CP1) 655- 1 - (Entire Document): Accept SUBMITFER: Technical Committee on Handling and Conveying of Dusts, Vapors, and Gases

I RECOMMENDATION: Withdraw NFPA 655, Standard for the Prevention of Sulfur Fires and Explosions. SUBSTANTIATION: The Committee does not believe that it has sufficient expertise to deal with the hazards of sulfur. The hazards of sulfur include those hazards associated with bulk and liquid storage; the Committee has only the expertise to make recommendations related to sulfur dust.

The Technical Committee will incorporate the sulfur dust requirements of N'FPA 655 into NFPA 654, Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing and Handling of Combustible Particulate Solids.

The Committee noted that perhaps a newproject can be proposed by sulfur experts in which the sulfur-specific requirements can be addressed with a different Technical Committee. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 25 VOTE ON COMMITTEE ACTION:

AFFIRMATIVE: 17 NEGATIVE: 1 NOT RETURNED: 7 Cappers, Clark, Ebadat, Guaricci,

Peterson, Roberts, Underwood EXPLANATION OF NEGATIVE:

GEORGE: 1 agree with Harold Weber's comments. NELSON: Negative vote on all items is due to the disagreement

that the standard should be withdrawn. At the last meeting persons knowledgeable about sulfur were present but were voted down when proposals were made. It is my opinion that a task groupshould have been created to rewrite the standard.

WEBER: I am submitting a negative vote on this Proposal until there is sufficient opportunity for industry to review and comment on the Committee's Proposal. No further action should be taken by the committee to either withdraw or alter NFPA 655 at this time.

(Log #4) 655- 2- (1-2.2): Reject SUBMITTER: Ray E. George, Chemithon Corp. RECOMMENDATION: Revise text as follows:

1-2.2 This standard shall not be intended to prevent the use of systems, methods, or devices that provide eqmvalent protection from fire and explosion, providing that suitable data are is~available to demonstrate equivalency. SUBSTANTIATION: The word data is the plural of the word datum. Plural nouns should be matched with plural verbs; i.e. "are" rather than "is." COMMI'FI'EE ACTION: Reject. COMMITTEE STATEMENT: NFPA 655, Standard for the Prevention of Sulfur Fires and Explosions, 1993 edition will be withdrawn [see Committee Proposal 655-1 (Log #CP1)], therefore no changes will be incorporated into the document. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 25 VOTE ON COMMYFrEE ACTION:



GEORGE: See my Explanation of Negative on Proposal 655-1 (Log #CP1).

NELSON: See my Explanation of Negative on Proposal 655-1 (Log #CP1). COMMENT ON AFFIRMATIVE:

WEBER= I support the changes as proposed.

(Log #2) 655- 3 - (1-4 Course Sizes of Sulfur, Finely Divided Sulfur (New)): Reject SUBMITrER: Ray E. George, Chemithon Corp. RECOMMENDATION: Add text as follows:

Include definitions for "Course Sizes of Sulfur" and "Finely Divided Sulfur".

267

N F P A 6 5 5 - - F 9 8 R O P

SUBSTANTIATION: The transition between "Finely Divided Sulfur" and "Course Sizes of Sulfur" can be inferred from "A-l-4 to occur at a mean particle size distribution of about 150 urn. However, it is unclear if this is the intent of the standard. COMMITTEE ACTION: Reject. COMMITrEE STATEMENT: NFPA 655, Standard for the Prevention of Sulfur Fires and Explosions, 1993 edition will be withdrawn [see Committee Proposal 655-1 (Log #CP1)], therefore no changes will be incorporated into the document. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 25 VOTE ON COMMITTEE ACTION:

AFFIRMATIVE: 16 NEGATIVE: 1 ABSTENTION: 1 NOT RETURNED: 7 Cappers, Clark, Ebadat, Guaricci,



GEORGE: I agree with Harold Weber's comments. EXPLANATION OF ABSTENTION:

WEBER: I abstain since there is no substantial information present to support the proposed change and all existing literature submitted in 1993 does not support this conclusion.

(Log #3) 655- 4 - (1-4 Sulfur Dust): Reject SUBMITTER: Ray E. George, Chemithon Corp. RECOMMENDATION: Revise text as follows:

Dust or Sulfur Dust.* Any finely divided solid sulfur that

~ revents a fire or explosion hazard. UBSTANTIATION: In general, the word "dust" is used in the

text of this standard to mean "sulfur dust." COMMITTEE ACTION: Reject. COMMITTEE STATEMENT." NFPA 655, Standard for the Prevention of Sulfur Fires and Explosions, 1993 edition will be withdrawn [see Committee Proposal 655-1 (Log #CP1), therefore no changes will be incorporated into the document. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 25 VOTE ON COMMITTEE ACTION:


Pete[son, Roberts, Underwood EXPLANATION OF NEGATIVE:



WEBER: See my Comment on Affirmative for Proposal 655.2 (Log #4).

(Log #1) 655- 5 - (4-3.5): Reject SUBMITrER: Ray E. George, Chemithon Corp. RECOMMENDATION" Revise text as follows:

4-3.5* In pits " used for melting sulfur, and in liquid storage tanks which arC regularly emDtied, cooled ~nd exposed to air (moisture). the liqu(d level shall not be permitted to expose the heating coils. The !'~":a . . . . . . . . . . . . . .k^l, _,.._)_ =~;'cr =.~.c

SU BS~ 'q T f fT ~O N : As stated, the usable tank volume can be reduced to less than 70 percent for horizontal cylindrical storage tanks, after providing sufficient heating surface by means of internal steam coils. Molten storage tanks used for continuous service do not have the potential that exists in temporary storage containers for the formation of iron sulfide compounds. Additionally, requiring heating coils to remain below the liquid level is somewhat at odds with requirements for heated vents and fill lines.

Iron sulfide formation occurs on steel components only when sulfur solidifies in the presence of moisture at the surface. Sulfur solidification does not occur on the heating surfaces of tanks which are not regularly emptied, cooled, and exposed to air (moisture). The second sentence in 4-3.5 is redundant. COMMITTEE ACTION: Reject. COMMITTEE STATEMENT: NFPA 655, Standard for the Prevention of Sulfur Fires and Explosions, 1993 edition will be withdrawn [see Committee Proposal 655-1 (Log #CP1)], therefore no changes will be incorporated into the document. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 25 VOTE ON COMMITTEE ACTION:





WEBER: See my Comment on Affirmative for Proposal 655-2 (Log #4).

268

Documents

[M]...James E. Maness, Bunge Corp., MO [U] Rep. Grain Elevator & Processing Society Guillermo A. Navas, Sheet Metal & Air Conditioning Contractors' Nat'l Assn., Inc., VA [M] Rep. Sheet