Air Flow and Air Pressurex

by:

Technical Bulletin

Environmental Dynamics

Published: 6/2005

Air Flow and Air Pressure

Technical Bulletin 112

Dynamics International


1

BULLETIN BRIEF

For aeration systems using diffused air (air diffuser systems), diffuser designs must be coordinated with the blower air supply design and the piping design for proper long term performance. Upgrades or replacement of diffuser systems also requires evaluation of the total air suppland piping system to assure proper performance.

Air is typically supplied to diffuser systems with lowapplication of blowers requires careful diffuser and piping system.

DISCLAIMER

Technical Bulletins are presented as a service by Environmental Dynamics International headquartered in Columbia, Missouri USA. For additional more information regarding this particular bulletin or your specific aeration application contact Environmental Dynamics International by calling +1.573.474.9456, toll free at via email at [email protected].


Copyright Environmental Dynamics International

diffused air (air diffuser systems), diffuser designs must be coordinated with the blower air supply design and the piping design for proper long term performance. Upgrades or replacement of diffuser systems also requires evaluation of the total air suppland piping system to assure proper performance.

Air is typically supplied to diffuser systems with low-pressure blowers. Design of these blowers or application of blowers requires careful review of air volume and air pressure characteristics of the

Technical Bulletins are presented as a service by Environmental Dynamics International headquartered in Columbia, Missouri USA. For additional more information regarding this articular bulletin or your specific aeration application contact Environmental Dynamics

+1.573.474.9456, toll free at +1.877.EDI.AIR8 ([email protected].


Environmental Dynamics International 2012 All Rights Reserved

diffused air (air diffuser systems), diffuser designs must be coordinated with the blower air supply design and the piping design for proper long term performance. Upgrades or replacement of diffuser systems also requires evaluation of the total air supply system

pressure blowers. Design of these blowers or characteristics of the

Technical Bulletins are presented as a service by Environmental Dynamics International headquartered in Columbia, Missouri USA. For additional more information regarding this articular bulletin or your specific aeration application contact Environmental Dynamics

AIR8 (877.334-2478), or

2

TECHNICAL BULLETIN 112

Operating air volume is generally a air volume for proper mixing. These calculations generally rely on oxygen transfer data and pumpage from diffuser manufacturers to al

Operating pressures are developed by engineering the system air hydraulics. Total system operating pressure must be developed taking the following parameters into consideration.

1. Diffuser membrane or unit pres2. In-basin piping friction losses to top of tank wall.3. Pressure losses in air distribution mains (headers) from the tank wall back to the blowers.4. Pressure loss through the blower system.

a. Piping and accessories or valvesb. Inlet filters c. Silencers

5. Water depth over the diffusers.6. Design increases in diffuser operating pressure vs. time.7. Safety factor in pressure calculations.

Note: typical operating pressures for fine bubble aeration systems are developed using diffuser submergence plus approximately 3-

For a system with water depth over diffusers of 12 ft, a system design for presubmergence + 3.5 ft friction losses + 0.5 psi safety factor. Total design for this example would be 15.5 ft water column (6.71 psi) + 0.5 psi over pressure design (S.F.). Total blower system design is then approximately 7.21 psi and used with the process air volume to select blowers and size blower motors and electrical controls.

Pressure and volume must be considered on any design of aeration systems, whether fine bubble, coarse bubble, new system or upgrade. For upgrade of diffuserblower pressure/volume characteristics when evaluating changing coarse bubble to fine bubble or even upgrading existing systems with the same type diffuser. Please confirm blower pressure and air volume characteristics as well as diffuser depth and air piping information on ALL requests for assistance with diffuser selection on diffuser design.



112 AIR FLOW AND AIR PRESSURE

Operating air volume is generally a process calculation of air volume for oxygen supply. These calculations generally rely on oxygen transfer data and

pumpage from diffuser manufacturers to allow selection of proper process air volumes.


Diffuser membrane or unit pressure loss. basin piping friction losses to top of tank wall.

Pressure losses in air distribution mains (headers) from the tank wall back to the blowers.Pressure loss through the blower system.

Piping and accessories or valves

ter depth over the diffusers. Design increases in diffuser operating pressure vs. time. Safety factor in pressure calculations.

Note: typical operating pressures for fine bubble aeration systems are developed using diffuser -4 ft water column losses plus safety factor.

For a system with water depth over diffusers of 12 ft, a system design for pressure may be 12 ft submergence + 3.5 ft friction losses + 0.5 psi safety factor. Total design for this example would be 15.5 ft water column (6.71 psi) + 0.5 psi over pressure design (S.F.). Total blower system design is

sed with the process air volume to select blowers and size blower

Pressure and volume must be considered on any design of aeration systems, whether fine bubble, coarse bubble, new system or upgrade. For upgrade of diffuser systems it is imperative to know blower pressure/volume characteristics when evaluating changing coarse bubble to fine bubble or even upgrading existing systems with the same type diffuser. Please confirm blower pressure and

well as diffuser depth and air piping information on ALL requests for assistance with diffuser selection on diffuser design.



oxygen supply or process . These calculations generally rely on oxygen transfer data and


Pressure losses in air distribution mains (headers) from the tank wall back to the blowers.

Note: typical operating pressures for fine bubble aeration systems are developed using diffuser

ssure may be 12 ft submergence + 3.5 ft friction losses + 0.5 psi safety factor. Total design for this example would be 15.5 ft water column (6.71 psi) + 0.5 psi over pressure design (S.F.). Total blower system design is

sed with the process air volume to select blowers and size blower

Pressure and volume must be considered on any design of aeration systems, whether fine bubble, systems it is imperative to know

blower pressure/volume characteristics when evaluating changing coarse bubble to fine bubble or even upgrading existing systems with the same type diffuser. Please confirm blower pressure and

well as diffuser depth and air piping information on ALL requests for

3

Pressure and air volume affect all blower systems; however, blowers have different design capabilities and limitations. In gener

1. Positive Displacement (P.D.) blowers are used for smaller airflows. P.D. blowers deliver constant volume regardless of pressure because power is the variable.

2. Centrifugal blowers are generally used for large air supply systems for reduced noise, reduced maintenance, and some operational benefits. Centrifugal machines are pressure units with variable air supply volume with small changes in pressures.

A full discussion of blower theory and application technology is beyond the scope of this anhowever, pressure and air volume are critical design variables for any aeration system. EDI will assist in your air pressure/volume design evaluations when you provide the system characteristics for new designs or for existing system upgrades.



Pressure and air volume affect all blower systems; however, blowers have different design capabilities and limitations. In general:

Positive Displacement (P.D.) blowers are used for smaller airflows. P.D. blowers deliver constant volume regardless of pressure because power is the variable. Centrifugal blowers are generally used for large air supply systems for reduced noise,

ced maintenance, and some operational benefits. Centrifugal machines are units with variable air supply volume with small changes in pressures.

A full discussion of blower theory and application technology is beyond the scope of this anhowever, pressure and air volume are critical design variables for any aeration system. EDI will assist in your air pressure/volume design evaluations when you provide the system characteristics for new designs or for existing system upgrades.



Pressure and air volume affect all blower systems; however, blowers have different design

Positive Displacement (P.D.) blowers are used for smaller airflows. P.D. blowers deliver Centrifugal blowers are generally used for large air supply systems for reduced noise,

ced maintenance, and some operational benefits. Centrifugal machines are constant

A full discussion of blower theory and application technology is beyond the scope of this analysis; however, pressure and air volume are critical design variables for any aeration system. EDI will assist in your air pressure/volume design evaluations when you provide the system characteristics

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Air Flow and Air Pressurex