When it comes to fire protection, we tend to get very focused on the fire pumps themselves and their proper operation. While there is plenty of innovation in the field around fire pumps and their control systems, there are still many issues with how they’re actually designed and installed in a system that we see on a daily basis.
One of the most common issues that can lead to damage and system failure with standby Diesel engine fire pumps is the way that cooling water is supplied. It is vital that manual isolation valves are fitted to the supply and discharge and that a recirculation loop can be provided for annual testing and leak detection. Failure to do so can result in a stale fuel issue with the engine as it runs on contaminated coolant, causing the heat exchanger to fail.
NFPA 20 requires that a Diesel fire pump drive only be used with pure, no-additive diesel fuel meeting the engine manufacturer’s precise specifications. Residual fuels, domestic heating oil, drained lubricating oils, biodiesel above a certain percentage and paraffin are not permitted.
The other issue that we run across frequently is that the entire system is pre-pressurized when it’s put in service. That means that if a sprinkler head is triggered or if there’s an electrical power loss to the fire pumps, the Diesel engines will start and will run until manually shut off. This isn’t the fault of the fire pump installers or manufacturers, but the fault lies in the design of the system, how it’s operated and maintained, and the physics of how the system works.