industrial exhaust velocity

[tolind]

I'm finding conflicting information and I would like some varied input. For industrial exhaust what is an acceptable duct velocity. I understand the capture velocity but sizing the ductwork is where my trouble lies. I've hear a max of 2500 fpm all the way to 5000 fpm. I don't want to much noise or vibration.

Thanks

 

[walkes]

It would depend on your ductwork, rectangular duct would have a lower maximum velocity than round ductwork. The following recommendations for industrial buildings are taken from the back of my Trane Ductulator sleeve:

Recommended velocity: Rect main 3000 FPM, Round Main 4000 FPM, Rect branch 2500 FPM, round branch 3000 FPM

Maximum velocity: Rect main 3500 FPM, Round Main 6500 FPM, Rect branch 3000 FPM, round branch 4000 FPM

 

[willard3]

"Industrial Ventilation" manual by American Conference of Governmental Industrial Hygienists has air velocities for various capture velocities and duct velocities to carry the exhausted material.

SMACNA also has a lot of information on air velocities.

2500 fpm is really very high for HVAC applications, but about right for grease cooking hoods.

5000 fpm will be right if you are carrying wheat products and etc. other solids.

You don't say what you are doing with the ductwork and its function is critical to establishing velocity.

 

[SAK9]

If you are trying to convey any dust particles,there is something called 'transport velocity' which is in the range of 4000-5000 fpm.As suggested by Willard3 you need to refer to Industrial Ventilation by ACGIH to choose the appropriate velocity for the material you are trying to convey.

Dust extraction systems do generate noise and is unavodable.
The fittings for duct extraction systems are different from the one you use for HVAC.If you have not done it before,leave it to some one who has done it before.

 

[cme]

What are you transporting?

All the solutions are within the book that willard3 posted about.

 

[ChrisConley]

NR Murphy has a guide that lists a wide variety of air velocitues for pneumatic conveying.

The highest they list is 7000 fpm for cement dust and sand.

http://nrmurphy.com/fans_air.html

 

[willard3]

The Buffalo Forge "Fan Engineering" manual has transport velocities for anything handled with air.

I fear the book may be hard to come by.....I have one.