Recall in Shaft for Machine Room-Less Elevators?

4/12/2019

We have a machine room-less elevator where the motor is located on top of the elevator cab and the elevator equipment is located within the elevator shaft.

NFPA 13 (2016) 8.15.5.3(2) allows sprinklers to be omitted from the hoistway of "traction elevators" where the hoistway is "protected by smoke detectors, or other automatic fire detection installed in accordance with NFPA 72", and several other requirements.

NFPA 72 (2016) 21.3.3 states that only the elevator hoistway and elevator lobby smoke detectors or other automatic fire detection (as permitted by 21.3.9) shall be used to initiate Phase I Emergency Recall Operation.

NFPA 72 (2016) 21.3.9 states that if "ambient conditions prohibit installation of automatic smoke detection" that other automatic fire detection initiating devices shall be permitted.

What type of ambient condition in an elevator shaft would qualify as prohibiting smoke detection?

I understand smoke detectors in elevator hoistways can cause nuisance alarms (NFPA 72 2016 A.21.3.9) and are very difficult to test and replace within elevator shafts, so in my opinion a heat detector would be better for elevator recall in the shaft if it's allowed by code.

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Donovan S.

4/12/2019 10:24:49 am

The are no Smoke detectors UL list to be installed in elevator pits or shafts. If sprinkler head is below 24", you do not have to shunt trip the power. However to comply with NFPA 72 you have to recall the elevator(s) to the alternate floor. That can be done with a heat at the top of the shaft set for recall only. If above 24" then you do it all (Recall and Shunt). You can also achieve the recall via a water flow detection. Most ppl think that the elimination of sprinkler head(s) in the elevator(s) shaft has to do with electrical. This is wrong, is has to do with the emergency breaks on the elevator. If they become wet, they may not work properly.

Ronnie Morales

4/12/2019 11:16:17 am

Statement from NFPA 72 (16) Handbook

Some elevator lobbies, hoistways, and machine rooms are not suitable environments for the installation of spot-type smoke detectors. Dust, dirt, humidity, and temperature extremes may exceed the operating parameters of the smoke detector. A spot-type smoke detector installed in the elevator lobby of an unheated parking garage would likely experience problems due to vehicle exhaust, dust, dirt, humidity, and temperature extremes. The intent of 21.3.9 is to prevent nuisance alarms from smoke detectors installed in such areas and unnecessary initiation of elevator Phase I Emergency Recall Operation.
Another type of fire detector may be substituted for a smoke detector where the authority having jurisdiction or another code requires detection in an area with ambient conditions unsuitable for a smoke detector. Also refer to 21.3.8.

Mike R

4/14/2019 01:43:10 pm

This is a perfect example of when you need to use some engineering judgment and good practice in addition to what is black and white in the book. It is true when there are no combustibles in a non-combustible shaft you want no sprinkler and no fire alarm detection in the shafts. However, when the controls and elevator equipment are in the shaft, the shaft itself becomes the machine room. Typically most elevator code officials will require some sort of detection at the top of shaft for this. A modern smoke detector at the top of a shaft (assuming conditioned, dry space) would be fine. If it not heated or an exterior elevator a heat detector would be best suited. I can't speak for every jurisdiction, but in Philadelphia the latest NFPA 13 is now in effect which allows no sprinklers in shafts OR machine rooms. Here elevator code takes precedence, and the code official wants nothing more than what is absolutely required, which in the case you mention above, would be a smoke only at the top of shaft.

Nguyen Nhat

4/15/2019 09:56:37 pm

Following SFPE hand book, Elevator codes generally don't require any sprinkler protection or detection at the top of shafts since the fuel load is insufficient to actuate a sprinkler or affect persons in the cars. So, the smoke detector is better than heat detector in this situation.

Recall in Shaft for Machine Room-Less Elevators?

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