A Comparison of design t h i f 1 t i l

A Comparison of design t h i f 1 t i ltechniques for zone 1 terminal

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Key IssuesKey IssuesFEATURES OF Exd DESIGN ENCLOSURE

•Only advantage to use an Exd enclosure is when the use of Ex components in an Exe enclosure is not possible

Many cover bolts means significant installation and maintenance time. Bolted

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Threaded or flanged covers must be regularly greased to avoid corrosion on flame path increasedcover often means a lower

IP ratingon flame-path –increased maintenance time

Enclosure CANNOT be drilled on site for additional entries due to need of pressure testing completed design

Hinges advised to avoid damaging cover when removed or to avoid need of liftingHeavy cast construction to need of lifting equipment for larger enclosures

Heavy cast construction to contain 1.5 times explosion pressure

Key IssuesKey IssuesFEATURES OF Exd DESIGN ENCLOSURE

BOLTED LID EXD SOLUTIONS ARE ONLY SUITED TO IIB GAS GROUPS

Design of the gaps on flameproof enclosures according to explosion groups

Width GapWidthof joint

Explosion group Explosion group Explosion groupp g pA and B

(IIC not possible, since the gap iswidened in the event of an explosion.

Ref. to 5.2.7 from 50018)

Explosion groupA, B and C

Explosion groupA, B and C

Flat joint Cylindrical joint Threaded joint

Key IssuesKey IssuesFEATURES OF GRP Exe/Exi DESIGN SOLUTION

Lightweight, fire retardant GRP enclosures provide superior impact and corrosion resistance(NEMA4X)

Mounting feet, molded in place

Light in weight, Tongue and groove IP 66 watertight sealing system

Smaller enclosures can have ‘cut down sides’, easy to be accessed and easy for wiring

Enclosures can be coupled to make a ‘modular system’ of unlimited size

Cable glands at bottom, plastic or metallic can be via removable and replaceable gland plates

Minimum number of Captive, stainless cover screws

Certifiable EExe EEx I or EEx e [ia]

GAS GROUPS IIA, IIB & IIC

AS STANDARD

Key IssuesKey IssuesFEATURES OF STAINLESS STEEL Exe/Exi DESIGN SOLUTION

Lightweight, Stainless steel enclosures provide superior impact and corrosion resistance(NEMA4X)

Light in weight, IP 66 watertight gasketed sealing system,

Water Channel designs possible

Cable glands at bottom, plastic or metallic can be viaCable glands at bottom, plastic or metallic can be via removable and replaceable gland plates

Low cost designs possible while still maintaining IP66 andCaptive, stainless cover screws Low cost designs possible while still maintaining IP66 and zone 1 protection with extremely high grade materials

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Certifiable EExe EEx i or EEx e [ia

GAS GROUPS IIA, IIB & IIC

AS STANDARD

Key IssuesKey IssuesIMPACT RESSISTANCE OF MATERIALS REGARDLESS OF DESIGN TECNIQUE

ACCORDING EN 50014/IEC50014 (general requirements for explosion protection)(g q p p )

CONFIRMS PLASTIC OR SHEET STEEL ENCLOSURES OF Exe DESIGN MEET THE SAME IMPACT RESISTANCE AS FOR FLAMEPROOF EXD ENCLOSURES

An electrical apparatus that has been tested at the lower degree of mechanical hazard, must be marked with the letter “X” so drawing attention to an entry in the certificate that it may not meet the maximum impact standard- ALL Crouse-Hinds Exe enclosures meet HIGH impact resistance regardless of material employed

Key IssuesKey IssuesExe TERMINATIONS AND INCREASED SAFETY

Definition

Increased safety “e” designates a type of protection in which measures have been taken to prevent, with increased safety methods, the possibility of inadmissible high temperatures and the occurrence of sparks or arcs in the inside or on the outside of electrical apparatus in or on which they do not occur in normal operation.

Terminals for external leads must be generously dimensioned and secured against self-loosening. They must be designed so that their contact pressure remains practically constant even in case of atemperature change within the normal range. They are also vibration resisting and so ensure a safeclamped and non heat producing termination of minimum resistance.p p g

To confirm these properties the terminals must be certified Exe for zone 1 and 2 use.

Together with a sealed and gasketed Exe approved enclosure maximum safety of the solution is ensured

EXAMPLES OF TERMINAL DESIGNS THAT CAN BE EXE

CERTIFIED

Key IssuesKey IssuesCOST OF OWNERSHIP

COST OF OWNERSHIP IS THE TOTAL COST OF BUYING AND MAINTAINING THE PRODUCT FOR THE DURATION OF THE INSTALLATION

When considering :-When considering :

•Cost of procurement

•Annual cost of maintenance

•Possibility of amending enclosure ( drilling of cable entries etc)

•Exe materials meeting 7NM are extremely high grade

•Exe materials are corrosion resisting and so have increased lifetime

•Exe Solutions are Equally safe to a well maintained Exd solution

•THE SUM TOTAL IS THAT A GOOD EXE SOLUTION IS MORE COST EFFECTIVE LOWER MAINTENANCE AND LASTS LONGEREFFECTIVE, LOWER MAINTENANCE AND LASTS LONGER

Key IssuesKey IssuesSummary Of Issues.Summary Of Issues.ISSUE Exd ExeCOST High cost of procurement and ownership due to

‘explosion proof ‘ flameproof enclosure.Lowest cost solution including cost of ownership. Simpler enclosure design as Ex protection is also provided by termination design

Maintenance after installation

High Maintenance due to flame-path care, binding of metal to metal contacts, many cover bolts

Low maintenance due to sealed and gasketed design

Impact resistance Impact resistance to zone 1 standard Impact resistant to zone 1 standardImpact resistance Impact resistance to zone 1 standard Impact resistant to zone 1 standard

Modification Internal components can be modified easily within the limits of certification but enclosure cannot be drilled or modified in any way except b f t d t t t

Enclosure may be drilled and in some cases modified or extended on site without high risk of endangering Ex protection. I t l t b difi dby manufacturer due to pressure test

confirmations.Internal components may be modified within the limits of the certification by use of locallly available components.

Ease of installation Highest cost installation due to heavy enclosure ( not good for shipping/offshore industry

Lowest cost installation, lightweight enclosure with minimum number of fixingsnot good for shipping/offshore industry

)requiring stronger fixings, need of Exd gland or seal, large number of cover bolts, greasing and general flame-path care

enclosure with minimum number of fixings to close cover, Low cost Exe glands can be used, no flame-path to be concerned with

Safety level Exd is an approved zone 1 design technique for Exe is an approved zone 1 designSafety level Exd is an approved zone 1 design technique for most zone 1 equipment. Perfectly safe in zone 1 or 2 IF routine maintenance is performed regulary to look after flame-path properties

Exe is an approved zone 1 design technique to house Exe or components encapsulated by other zone 1 technique. Perfectly safe in zone 1 or 2 with minimum maintenance