Lab Exhaust Fan Shutdown
Lab Exhaust Fan Shutdown
(OP)
Is there any code that requires that laboratory exhaust systems be shut down by the building fire alarm system in the event of fire. These would include lab hood exhaust, biosafety cabinet exhaust and general lab exhaust. Seems to me that you would want these fans to be on during a fire to ensure that the bad "stuff" being exhausted doesn't get involved in the fire and make the smoke situation worse.





RE: Lab Exhaust Fan Shutdown
RE: Lab Exhaust Fan Shutdown
RE: Lab Exhaust Fan Shutdown
RE: Lab Exhaust Fan Shutdown
RE: Lab Exhaust Fan Shutdown
Slowing down the fans would not be enough. You would also need to reset the air valves accordingly to reduce the exhaust at each point. In addition to emergency power, there should be multiple exhaust fans (& supply fans) for reliability.
With dual fans, operation at one fan would reduce volume to approximately 60 to 70%. Thus at one fan operation w/ normal dual fans, the air valves should be reset to a setback position that would approximately maintain the design pressurization & without exceeding the 15 lb limit to open doors, and the capacity of the single fan.
If the air valves are not reset, control would not be maintained at the remote portions of the ductwork.
RE: Lab Exhaust Fan Shutdown
Yes, air valve volumes were reset (or the remote valves would draw little air with the closer valves wide open), and there are multiple fans (3 at one location, four at the second - one in each group is redundant).
Originally we suggested partial fan shutdown, but the AHJ's intreprtation was the code requires all of the operating fans to remain on, so we just slowed them down. All the drives have a gateway to our EMS, and we were able to fine tune the speed to get just below the 15lb force.
Different ways to skin the cat!