Maintaining a Diesel Fire Pump
0The diesel fire pump is the heart of a fire protection system, providing high-pressure water at an increasing rate when called upon to do so. It is the most expensive component of any fire protection system, making it essential that it be properly maintained to ensure its long life span and ready to be used when needed. This requires the same level of attention as any other mechanical equipment, and includes regular service to its engine. Failure to perform this maintenance will dramatically shorten its lifespan and cause it to become unreliable when called upon to protect the facility from a dangerous and deadly fire.
When the fire pump is activated, it is required to maintain a specific pressure and flow based on its rated capacity. This can be accomplished using two methods. One is to use a heat exchanger with the incoming water, which uses the cooling water as an effective adsorbent of the heat generated by the pump during operation. This method is preferred by NFPA 20, as it eliminates the need for a casing relief valve, which can be susceptible to leaks.
Another method of maintaining the fire pump’s performance is to perform periodic flow tests, which are similar to the service performed on a car. Flow test results are plotted on hydraulic graph paper and compared to a factory test curve provided with the fire pump, available in its operation and maintenance manuals, or on the pump’s nameplate. In addition, some digital ITM platforms can automatically plot these data points and generate reports. If there is a significant drop in the fire pump’s rated performance compared to that shown on the original factory test curve, it must be investigated to determine what has changed and what corrective action is required.
Other responsibilities of a fire pump manager include ensuring that the fire pump room is properly sprinklered per NFPA 20. This is a safety concern because the fire pump room must be protected from flood waters and explosions that could damage or destroy the fire pumps, especially the diesel engines. The fire pump manager should also verify that the driver for the fire pump, whether it is an electric motor, steam turbine or diesel engine, is sized to meet the full horsepower demands of the pump and that it meets UL and FM requirements with a certified factory test curve.
The sizing of the fuel tank for a diesel fire pump is determined by the anticipated duration of the fire that it will be used to fight. NFPA 20 specifies that the tank should hold one gallon of fuel for every horsepower of the fire pump’s engine, plus five percent for expansion and five percent for sump. This allows the emergency responders to operate the fire pumps for up to eight hours at a time.
The diesel fire pump must be fueled regularly to keep it operating reliably. NFPA 20 standards require the diesel fuel tanks to be heated to 120 degF, and Hotstart offers a full line of thermostatically controlled heaters to maintain this temperature. diesel fire pump