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Recommended Exhaust Velocity for Vehicle Exhaust Capture

Recommended Exhaust Velocity for Vehicle Exhaust Capture

Recommended Exhaust Velocity for Vehicle Exhaust Capture

(OP)
Is there a standard that points to the recommended duct velocity to source capture and convey vehicle exhaust (non-diesel)?

RE: Recommended Exhaust Velocity for Vehicle Exhaust Capture

I believe for smoke I have used 2000 ft/min

RE: Recommended Exhaust Velocity for Vehicle Exhaust Capture

Have you thought about a tail pipe connection? The ACGIH would provide you with a good standard detail and flows.

RE: Recommended Exhaust Velocity for Vehicle Exhaust Capture

(OP)
We're using tailpipe connections for capture (around 3000fpm from a variety of sources) and 1500-2000 fpm for conveying. Once we've 'ganged' together a number of connections I was looking to see if there was a standard conveying number.

Thanks for the comments so far!

RE: Recommended Exhaust Velocity for Vehicle Exhaust Capture

The ACGIH provides a standard, as well as illustration in Chapter 10, Specific Applications. The ACGIH uses 2,000 fpm for the conveying number.

RE: Recommended Exhaust Velocity for Vehicle Exhaust Capture

You're probably ok with a velocity as low as 1500 FPM.

RE: Recommended Exhaust Velocity for Vehicle Exhaust Capture

I'm having a new fire station built.  in the design and spec process.  two different schools of thought on ventialating the truck bays.  
1- is a whole house system with carbon monoxide sensors at ceiling to turn on large exhaust fans (2) moving diesel smoke from the breathing area.
2- is a vehical exhaust extractraction at the tail pipe system.
1 is less effective. 2 cost more.
your thoughts.

RE: Recommended Exhaust Velocity for Vehicle Exhaust Capture

(OP)
The major downside to having a 'whole house' exhaust system is that you end up with people breathing diesel fumes the whole time the trucks are running.

Sure, the exhaust is eventually removing the fumes, but the fumes still have to travel from the tailpipe to the exhaust louvre, right through the fire fighter's breathing zone.

The tail pipe extraction system will be more effective, and will have a lower life cycle cost as less exhaust is required.

RE: Recommended Exhaust Velocity for Vehicle Exhaust Capture

"whole house" can be done safely, but...........    If you don't have exhaust pipe hose(s), you will be pulling a lot of air in to safely dilute fumes, pull them upward, and exhaust them.  This will be a big problem in colder weather.  You should look at ex pipe hoses AND room ventilation with fresh air coming in at a lower volume rate.  Cost can only be a factor in comparing safe systems.  (I had low end CO poisoning from car exhausts in garage many years ago.  It is scary as it stays in your body for a day, if you don't get major poisoning and end up in hospital, brain-damaged, or dead).  Use ACGIH Industrial Ventilation as first guide.

I agree with 2000 FPM velocity.  You may be able to go a little lower (1500?) if no smoke and system configuration justifies it.  Smoke is suspended particulate.
 

RE: Recommended Exhaust Velocity for Vehicle Exhaust Capture

Philadelphia, PA (USA) Fire Department is doing a mandatory upgrade to piped exhaust.  They have sleeping quarters adjacent to trucks, and no matter how much ventilation, there is a cumulative exposure problem for occupants.  Suggest there really isn't a trade off decision to make here, the answer is ducted exhaust.  Assures compliance, energy costs will only go up, and exposure awareness will probably legislate this eventually anyway.  Their design is a roll up hose, by vehicle, that extends from the back wall to the front garage door.  Start and drive away and it automatically detaches and retracts.  Back in, stop at the door threshold and hook on the hose before backing in further.  This design allows for routing checking/testing (common in this application) with vertually no exposure.

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