Author(s): Russell Fleming Published on November 1, 2011

Ups and Downs
Sprinkler protection of elevators and machine rooms

NFPA Journal®, September/October 2011 

Before the 1994 edition of NFPA 13, Installation of Sprinkler Systems, elevator shafts were treated like any other vertical shafts and were not subject to specific requirements. They were simply protected with a sprinkler at the top and, assuming noncombustible shaft walls, another sprinkler "near the bottom."

FROM THE ARCHIVES

September - October 2011
Revamping, remodeling, and reinstallation

July - August 2011
A discussion of the "small room rule"

May - June 2011
Sprinkler protection of ductwork with combustible contents

March - April 2011
NFPA 13 and maximum time limits for audible alarms

January - February 2011
Meeting minimum-temperature requirements for wet-pipe systems

November - December 2010
Opinion should never be accepted in lieu of informed consensus judgement 

In the 1994 edition of NFPA 13, a new section entitled "Elevator Hoistways and Machine Rooms" was introduced that clarified the point that sprinklers were not needed near the bottom of a noncombustible elevator shaft that did not contain combustible hydraulic fluids. Also, in cases where a sprinkler was needed in the pit to address debris that could accumulate over time, a sidewall sprinkler could be located near the side of the pit near the elevator doors, not more than two feet (0.6 meters) above the floor, thereby minimizing interference with elevator operation.

The 1994 changes also allowed the omission of the sprinkler at the top of a noncombustible passenger elevator hoistway where the car enclosure materials met the requirements of the ASME A17.1 Safety Code for Elevators and Escalators. In the 2010 edition of NFPA 13, the rule was amended to allow omission of the sprinkler where the hoistway is of limited-combustible construction. A new rule was added to require sprinklers at the top and bottom of hoistways for elevators that use polyurethane-coated steel belts or similar combustible belt materials.

As part of the 1994 revisions, an annex was added to note that the widely adopted ASME A17.1 requires that the power to the elevator be shut down upon or before the application of water in elevator rooms or hoistways. The shut down could be accomplished by a detection system sensitive enough to operate before the sprinklers activated. Alternatively, the system could use devices capable of shutting down power before significant sprinkler discharge took place. The intent was to cut power before the potential loss of elevator control due to shorting of equipment from water discharge or the potential loss of traction in the hoistway due to wetting of brakes.

However, ASME A17.1 also required that elevators be recalled to lobby level prior to power shut down to ensure that passengers were not trapped on elevators in the hoistways. In the 1999 edition of NFPA 13, an annex note was added to clarify that ASME A17.1 exempted sprinklers installed within two feet (0.6 meters) of the bottom of the pit from the special arrangements of inhibiting water flow before elevator recall.

Despite the changes, the elevator industry has remained wary of the possibility that power could be shut down too soon due to the presence of sprinklers in the machinery room, trapping passengers. As it prepares the 2013 edition of NFPA 13, the Sprinkler Committee is proposing to allow sprinklers to be omitted from traction elevator hoistways and their associated machinery spaces, provided no combustible materials can be stored and that all spaces include smoke or fire detection systems. The new rules would not apply to hydraulic elevators, which are generally used in buildings of four stories or fewer.

While the success of such a change would require proper enforcement of the limitation on stored combustibles, it would create an incentive to avoid hydraulic elevators at a time when new, lower-cost, geared-traction elevators that don’t require machine rooms are gaining an increasing share of the market in low-rise buildings. Taken together, these changes could totally eliminate new installations of sprinklers in elevators and machine rooms.


Russell P. Fleming, P.E., is the executive vice-president of the National Fire Sprinkler Association. 

 

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