Reliability of a Diesel Fire Pump

A diesel fire pump is a critical component of a building’s fire protection system. The system is designed to produce high-pressure water at an increasing rate during a fire emergency, so it’s crucial that it’s reliable during a crisis. Fire pumps are one of the most expensive pieces of equipment in a fire protection system and it is not uncommon for them to last 20 years. However, not all fire pumps are created equal and some may require more attention than others. To ensure that a fire pump will operate during an emergency, it’s important that the fire department or emergency response team know the intricate details of how the engine operated.

Fire pump reliability relies on a number of components, including fuel supply and combustion air, ventilation, operating environment and engine cooling. Each of these needs to be accounted for during the design and installation process. If the system is not correctly designed or installed, it may not be reliable during a fire emergency.

An example of this occurred when a high wind caused the electric motor controller to fail at a building that had an automatic diesel-driven fire pump as an alternate power source for emergencies. When the failure occurred, there was no backup power available and the fire pump ran until its heat exchanger seized. The resulting damage to the pump resulted in expensive repairs to the fire pump and facility.

This can be avoided by ensuring that the engine is located in an ambient temperature that is compliant with NFPA 20 and the manufacturer’s specifications. Using a thermostatically controlled heater to maintain this condition can help ensure that the engine will start under all conditions.

The fuel tank for the diesel fire pump must be sized appropriately to allow for adequate operation. This is typically done by utilizing a diesel fuel tank size calculator and comparing the results to the maximum tank capacity specified by the fire pump manufacturer. A minimum of two-thirds of the maximum capacity must be available for full load operation of the fire pump.

All wiring between the fire pump controller and the engine must be properly sized and connected to prevent failures during a power outage. The fire pump should have a low fuel level switch mounted in the diesel fuel tank and wired to the fire pump controller. The engine should also be able to be shut down in the event of a power loss by manually placing the selector switch located inside the fire pump controller into the off position or by activating the engine run contact.

The exhaust system of the diesel fire pump must be properly sized and insulated to keep heat transfer to the pump room to a minimum. The size of the silencer selected, length of pipe run and fittings should be evaluated by a professional to ensure that the back pressure on the diesel engine is not compromised.

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