Consulting-Specifying Engineer - August 2007 - (Page 36)

Fire Safety for Elevator Systems BY TALAL M. RABIAH, P.E., supervising mechanical engineer, Syska and Hennessy Group, San Diego HVAC and levator industry resources estimate that there are about 900,000 installed elevator systems in the United States. Hydraulic elevators con- E stitute nearly 70% of the vertical transportation (VT) market and 30% are of the traction type. Hydraulic elevators typically are installed in low- and mid-rise buildings as high as four stories. Traction elevators are installed in buildings of all heights but have the advantage of higher speed for taller buildings. In addition, engineers must ensure that elevators’ hoistways conform to strict NFPA requirements. Smoke control in elevator hoistways, elevator lobbies and stairways must be controlled by a UL 864 listed alarm system meeting the requirements of NFPA 72. Elevator cartop electrical components should be enclosed in NEMA 4 enclosures to resist water that may drip on top of the car while the fire is being extinguished. A new type of elevator that has been aggressively gaining momentum in the VT market is the machine room-less (MRL) elevator. MRL elevators can be used efficiently in buildings as high as four stories and have the advantage of not requiring dedicated non-leasable area for equipment. MRL elevators still require a small machine room to house the controller and a man-size access door to the hoistway for access to the elevator machine, which is mounted inside the hoistway as part of the ropes-and-sheave system. While eliminating the bulk of the machine room, MRL elevators still share some HVAC design requirements found in hydraulic and traction elevator hoistways and cars. Hydraulic and traction elevators require machine rooms adjacent to the elevator hoistway and therefore take up leasable area in buildings, while requiring additional support services that include dedicated HVAC. The mechanical engineer’s design that relates to the elevator system and ventilation requirements for the machine room and elevator hoistways are a key to the safe and efficient operation of a building system. Traction elevator machine room This room normally houses the elevators, machines, controllers, governors and related electrical components. Room size is approximately 12 ft. x 12 ft. for one elevator system including maintenance space requirements, or 20 ft. x 12 ft. for two systems. Traction elevator machine rooms, while separate from the elevator hoistway, do 36 Consulting-Specifying Engineer • AUGUST, 2007

Table of Contents Feed for the Digital Edition of Consulting-Specifying Engineer - August 2007

Contents M/E Roundtable Giants 100 Pullout Poster Giants Stand Tall: CSE Giants 100 Report Electrical Design for Tall Buildings HVAC and Fire Safety for Elevator Systems How to Beat the Codes GAS Technology Supplement Recovering Waste Heat from Boilers New Applications for Tankless Water Heating Systmes Techniques Improve for Powder Coating MDF New Tools Available for Heat Treating Steel Direct Drive Engines

Consulting-Specifying Engineer - August 2007

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