Frequently Overlooked Issues in Designing Fire Pump Systems

Some important considerations are often missing in fire pump system design. Asking the following questions will help the designer avoid overlooking some key concerns: Were adjustments made for altitude, pump-room temperature and for a right angle drive on a diesel-engine pump? On one engine derating table, the temperature graph begins at 77ºF.

04/01/2004


Some important considerations are often missing in fire pump system design. Asking the following questions will help the designer avoid overlooking some key concerns:

Were adjustments made for altitude, pump-room temperature and for a right angle drive on a diesel-engine pump? On one engine derating table, the temperature graph begins at 77

Have all of the devices in the suction line been included in the design? This is so that the correct inlet pressure to the pump can be determined. Devices include check valves, gate valves, elbows, tees, backflow devices, reducers and meters. If everything is not included, the pump discharge pressure may be too low to supply adequate pressure and flow.

For diesel-engine pumps, is the bottom of the fuel tank at or above the level of the injectors? The required location for the fuel storage tank is the fire pump room, with the bottom of the tank at or above the fuel injectors. In this way, even if the fuel pump fails, fuel can still be gravity fed into the engine without shutting down.

Is the suction pipe installed so that it will not have an air pocket next to the suction inlet? One of the most common problems in fire pump installations is the eccentric reducer in the suction piping. When this occurs, the suction piping is not level with the pump inlet, and air is trapped in the piping. When started, the pump sucks in air causing cavitation inside the pump.

Is an electric-motor fire pump equipped with a casing relief valve? These pumps are all required to be equipped with a small, 3/4-in. to 1-in. pressure-relief or solenoid valve that opens when the pump is started and stays open until the pressure in the discharge piping is reduced when the water discharges.

Are heating and cooling adequate in the pump room? The heating load must take into consideration the radiant energy produced by the diesel engine. The derating of the temperature is used to make sure that the engine will operate under all conditions.

Has the designer considered the pressure rating of the fire-protection system installed downstream from the fire pump? There is a greater need today for fire pumps that have very large capacities and lower pressure limitations on the discharge to keep pressures below the rating of the pipe, fittings and sprinklers.

Is a backflow prevention device required by the AHJ to be installed upstream from the fire pump? At present, good engineering practice in most areas requires the use of a backflow device where the water is taken from the potable water source and pumped into a fire protection system.

These are just a few often overlooked fire pump system design concerns. For the complete article, go to the Fire, Life Safety and Security community at www.csemag.com by clicking the red button on the left.



Fire Pump Design Checklist

Adjust for altitude and temperature

Include all devices in the suction line

Properly position diesel fuel tanks

Include relief valves on electric pumps

Consider system pressure rating downstream from pump

Install backflow prevention device



No comments
Consulting-Specifying Engineer's Product of the Year (POY) contest is the premier award for new products in the HVAC, fire, electrical, and...
Consulting-Specifying Engineer magazine is dedicated to encouraging and recognizing the most talented young individuals...
The MEP Giants program lists the top mechanical, electrical, plumbing, and fire protection engineering firms in the United States.
Combined heat and power; Assessing replacement of electrical systems; Energy codes and lighting; Salary Survey; Fan efficiency
Commissioning lighting control systems; 2016 Commissioning Giants; Design high-efficiency hot water systems for hospitals; Evaluating condensation and condensate
Solving HVAC challenges; Thermal comfort criteria; Liquid-immersion cooling; Specifying VRF systems; 2016 Product of the Year winners
Driving motor efficiency; Preventing Arc Flash in mission critical facilities; Integrating alternative power and existing electrical systems
Putting COPS into context; Designing medium-voltage electrical systems; Planning and designing resilient, efficient data centers; The nine steps of designing generator fuel systems
Designing generator systems; Using online commissioning tools; Selective coordination best practices
As brand protection manager for Eaton’s Electrical Sector, Tom Grace oversees counterfeit awareness...
Amara Rozgus is chief editor and content manager of Consulting-Specifier Engineer magazine.
IEEE power industry experts bring their combined experience in the electrical power industry...
Michael Heinsdorf, P.E., LEED AP, CDT is an Engineering Specification Writer at ARCOM MasterSpec.
click me