Fire alarm horn inside of a walk-in air handler??

[salm10]

Has anyone ever heard of a local fire marshall requiring an a/v indicating device inside of an air handler? I am working with a local AHJ and he seems to think so. This is an air handler with about a 75 hp motor inside of a walk in built up box. The only time anyone would be in there is to change filters, service the motor, etc. I can't think of any reason why anyone would be in there with the fan running, but the AHJ is claiming that you cannot hear the horn in the mechanical room if you are standing in the fan.

Has anyone ever had to install horns in this kind of equipment?

 

[broadgage]

In years gone by, it would have been very dangerous to enter a large AHU with the fan running on account of the risks from a belt driven fan.
These days, the fan and belt drive are normally well enclosed with mesh, and persons might well enter the AHU whilst it was running in order to replace filters or check for leaks.
I normally change filters with the fan running.
It would therefore seem reasonable to require a fire alarm sounder and/or strobe light inside the unit.
An exception could be reasonably be made if the AHU is interlocked with the fire alarm as is often the case. The stopping of the fan would alert any person within, and without the noise of the fan they should be able to hear the alarm.

Here in the UK it is common practice to mount fire alarm sounders on the OUTSIDE of an AHU, rather than on the wall or ceiling of the plant room.
This is considered to be audible both within the AHU and elswhere in the plant room.

 

[steve66]

Although Broadage's response seems reasonable, I don't think an AHU would fall into any of the spaces where a FA horn or strobe would be required. Its not a public or common space.

And I feel more strongly if the fan can be shut off for maintenance. There isn't any reason to work on a AHU with the motors running if you don't need to.

The odds of a fire happening in the couple of minutes someone is replacing filters seems pretty small.

I'd ask for a code reference.

 

[mtfallsmikey]

I got dinged on this one by a FM myself. his code reference was IBC 907.9.2. He considers all spaces, mech. rooms as well as LAN rooms "occupied" space.

 

[steve66]

I got dinged on this one by a FM myself. his code reference was IBC 907.9.2. He considers all spaces, mech. rooms as well as LAN rooms "occupied" space.

Maybe its just me, but from my experience, the local Fire Marshall's know the least about any of the codes. They may be great at putting out fires, but for inspections, they seem to go by "Thats how we've always done it" or "Thats how its always been".

But then again, we have a lot of rual areas around here, and a lot of volunteer fire depts.

 

[jusme123]

I got dinged on this one by a FM myself. his code reference was IBC 907.9.2. He considers all spaces, mech. rooms as well as LAN rooms "occupied" space.

Just curious, what if you had fan shutdown upon activation of fire alarm, you would than hear/see the horn/strobes?

 

[jusme123]

I got dinged on this one by a FM myself. his code reference was IBC 907.9.2. He considers all spaces, mech. rooms as well as LAN rooms "occupied" space.

[F] 907.9.2 Audible alarms. Audible alarm notification appliances shall be provided and shall sound a distinctive sound that is not to be used for any purpose other than that of a fire alarm. The audible alarm notification appliances shall provide a sound pressure level of 15 decibels (dBA) above the average ambient sound level or 5 dBA above the maximum sound level having a duration of at least 60 seconds, whichever is greater, in every occupied space within the building. The minimum sound pressure levels shall be: 70 dBA in occupancies in Groups R and I-1; 90 dBA in mechanical equipment rooms and 60 dBAin other occupancies. The maximum sound pressure level for audible alarm notification appliances shall be 120 dBA at the minimum hearing distance from the audible appliance. Where the average ambient noise is greater than 105 dBA, visible alarm notification appliances shall be provided in accordance with NFPA 72 and audible alarm notification appliances shall not be required.

Exception: Visible alarm notification appliances shall be allowed in lieu of audible alarm notification appliances in critical-care areas of Group I-2 occupancies.





Only a strobe, if anything, would be required within the unit

 

[mtfallsmikey]

Maybe its just me, but from my experience, the local Fire Marshall's know the least about any of the codes. They may be great at putting out fires, but for inspections, they seem to go by "Thats how we've always done it" or "Thats how its always been".

But then again, we have a lot of rual areas around here, and a lot of volunteer fire depts.

I requested any faults/anomalies written up be accopmanied by a code reference...that brought a little wailing and gnashing....

Just curious, what if you had fan shutdown upon activation of fire alarm, you would than hear/see the horn/strobes?

Yes, I could hear it from the corridor with the door closed, but not in my pump rooms..... can't rely on the AHU shutdown, what if a sprinkler head goes off, and a flow alarm trips the panel? The AHU will still run. Had some of the tenant's areas written up too, no notification, or visual only, as well as a syncronization issue on one of the floors. The FM had no clue that NFPA is rethinking the issue about using elevators for evac.