Consulting-Specifying Engineer - August 2007 - (Page 37)

communicate by multiple openings for ropes or cables serving the cars that introduce air flows into the machine room. The major heat generating equipment in the machine room is the elevator machine motor that raises and lowers the elevator car through several steel ropes, and the controller. The controller must operate within temperature parameters and therefore is fan vented. Simple controller ventilations systems draw machine room air into the controller enclosure, pass it over the electronic equipment and discharge it back into the machine room, where the machine room AC system is able to handle the cooling load. Machine room air that serves the controller in addition to the remainder of the space has to be clean with filtration covers on the machine ventilation discharge opening where carbon particles also are discharged. Hydraulic elevator machine room The hydraulic elevator machine room is usually 25% to 50% smaller than the traction elevator machine room. There is no air transfer relationship with the hoistway as with traction elevators because only a 2-in. wide steel pipe connects the hydraulic machine and the hoistway piston. The penetration openings to the hoistway are caulked with a UL fire-resistant rated sealant to maintain the hoistway fire rating and ensure a smoke tight seal as well. The 2-in. wide steel pipe carries 400 psig hydraulic oil that is used to raise or lower the car cylinder. The hydraulic unit and elevator controller generate heat, therefore air conditioning is needed for the machine room in order to keep the hydraulic oil temperature at normal operating temperatures. AC system capacities are similar to traction elevator machine rooms. Machine room design When designing an elevator machine room HVAC system, a cooling load calculation is required to determine the BTU/hr that the AC system requires. The elevator machine HVAC system, due to its exposure to the equipment and a need to have it operate off of emergency generators, leads the designer to an independent system separate from the building HVAC system. A typical 3,000-lb. capacity elevator usually requires a 1.5-ton to 2-ton AC system depending on the machine room’s location in the building and the climate for the local. ASME A17.1, “The Safety Code for Elevators and Escalators,” requires machine room temperature to be as determined by the elevator manufacturer. Most building elevator mechanics and manufacturers maintain elevator machine Image courtesy of Kone MRL F H Suction and liquid pipes with weatherproof insulation Room ceiling 6 in. Outdoor condensing unit concealed by landscape Wall Pipe sleeve with caulking Bolt unit to steel plate. Width matches condensing unit’s width 6 in. 2 in. pipe Steel plate along bottom of condensing unit, welded to pipe. Wall MTD room, thermostat 5 in. AFF (furnished Indoor unit, wall mounted 6 in. below machine room ceiling and installed by contractor) 1 in. condensate waste to condensing pump, copper type L 115 volt, 1 phase, wall-mounted dual pump package 0.5 in.-thick, 6 in. x 6 in. steel plates bolted to 2 in.-thick condensing pad 0.75 in. copper type L, insulated to an open sanitary waste Check valve 2 in.-thick condensing pad, 1 in. larger than unit all around Figure 1: Machine room AC system detail (No scale) Consulting-Specifying Engineer • AUGUST, 2007 37

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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