Detector for Machine Room Less (MRL) Elevator?

12/6/2023

We have a passenger elevator that is a traction, machine room-less (MRL).

Under NFPA 13, 2013 Edition, Section 8.15.5.2, a 'sprinkler shall not be required for enclosed, non-combustible elevator shafts that do not contain combustible hydraulic fluids.'

NFPA 72, 2013 Edition, Section 21.3.6 states that 'smoke detectors shall not be installed in unsprinklered hoistways unless they are installed to activate the elevator hoistway smoke relief equipment.'

I believe these would apply to this elevator.

Does the elevator only require lobby smoke detectors, including first floor for recall and second floor for alternate recall?

Is a smoke detector actually required within the shaft?

This is my first MRL elevator and I want to make sure we cover everything that's required.

I would appreciate you views on this, thank you!

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9 Comments

Dan Wilder

12/6/2023 07:04:42 am

From a sprinkler contractor so...best suggestion is to reach out to the installing elevator contractor; they seem to also have state requirements in a PDF for distribution.

The MRL box will have two detectors located within (1 heat and 1 smoke, typically the upper left or right sides - we've seen both) as the box itself is required to have a sprinkler.

As for the shaft, while this section (8.15.5.2) allows the omission of sprinklers in the pit, verify that the hoist way AND the car enclosure meet the requirements of ASME 17.1a-1985 & later Rule 204.2a to avoid the sprinkler at the top of the shaft per 8.15.5.6.

Looking back through the OTIS guidelines we were given on the last project, the belt ratings triggered a sprinkler requirement (<3500# = sprinklers, >4000#=No sprinklers) so may want to verify that as well (not sure why, it was on the sheet)

Jesse

12/6/2023 08:07:19 am

Dan is on the right track with the belt-ratings. Sometimes belt ratings can trigger a sprinkler in the hoistway.

Danial Bartle

12/6/2023 08:23:52 am

We have several 2-stop elevators of the same design. Smoke is required at the top of the shaft if the motor is in the shaft.

Scott McCormick

12/6/2023 12:00:19 pm

I also believe that the belts are considered combustible and that fire sprinkler in the top of the shaft is required. Check NFPA 13 again

12/6/2023 12:12:27 pm

I meant flammable not combustible. Sorry

Glenn Berger

12/6/2023 12:45:27 pm

I have not seen consistency with these types of elevators yet. With the machinery equipment typically typically on top of the cab, many AHJs consider the hoistway to be containing combustibles.

12/6/2023 09:10:37 pm

Thanks all. I appreciate your comments and will act on them.

Rob B

12/7/2023 10:02:03 am

I cant believe that after all these years this is even a thing. NFPA 13 just gets this wrong. How absurd is it not to protect an elevator shaft and/or machine room. This is no matter the construction of the shaft or flavor of the elevator. People can easily become trapped, this is life safety we are taking about. I personally wouldn't want to be in any elevator (elevator shaft by default) where there was zero protection for anything, just relying on some POS paper thin metal skin sliding door for protection from the floors. Or worse, maybe an actual fire of the mechanics or car electrical. Just stupid...

sean

12/31/2023 05:53:41 pm

how does this match up with the need to have a way to handle automatic recall? I feel there is a bit of a gap in the code here.

Detector for Machine Room Less (MRL) Elevator?

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