NFPA 25 TABLE 8.1.2 - DIESEL FIRE PUMP ENGINE OIL AND WATER CHECKS
The above photo is the inside of a diesel fire pump engine heat exchanger expansion tank. Normally there should be water in it, about 2" from the top for expansion when the engine heats up to prevent boil-over on older engines with no overflow recovery tanks. The sludge seen in it is a result of a ruptured oil cooler and heat exchanger failure due to the engine overheating. The excess heat usually causes internal solder joints to fail.
The oil cooler failure allowed the water and oil to "swap places." The heat exchanger failure resulted in the internal jacket water pumped out the cooling loop discharge onto the ground, seen by the antifreeze stains at the discharge.
NFPA 25 FOR DIESEL ENGINES requires several things in the oil and cooling systems to be checked like the oil, water and hoses as above in addition to those below. Any low levels and/or foreign materials, including diesel fuel, need to be addressed ASAP
ADDITIONAL INFORMATION
OIL AND WATER FAILURES - From the above same engine with oil cooler and heat exchanger failures.
CRACKED HEAT EXCHANGER HOSE - Different engine
ADEQUATE COOLING WATER TO HEAT EXCHANGER - This is determined by the COOLING LOOP GAUGE on the engine. These gauges are usually 0 - 60 PSi, 1.5" gauges. Typically the pressure will vary from 15, to 20 up to 30 PSI on older engines. Defective cooling loop gauges can produce false readings if the gauge is sprung like from freezing - see sensing line gauge EXAMPLE.
WATER STRAINERS - If these clog, it will show up on the cooling loop gauge as low pressure readings. The "Y" strainers on the engines allow them to be isolated with the valves, and the typical 3/4" drain plug removed. Cracking the upstream valve will allow supply water to flush debris out into a small cup for examination. The strainer on the right in the photo is the automatic side with the cooling loop solenoid. It resulted in the engine overheating and setting the engine wiring harness on fire. Removing the larber pipe busing allows the strainers to b removed for cleaning.
JACKET WATER HEATER - Varies from 120 - 140 degrees F (current NFPA 20), older units may be set 100 - 120. Linked in PULSE article.
Fire Pump Technician
9 年Mike, Thank you for another great article. I would like to add to the diesel engine maintenance topic. If you refer to NFPA 25 2014 edition, they have added annual testing of the diesel fuel. Diesel fuel begins to degrade after 28 days of storage. With 250+ gal. tanks and lack of engine run time, one can only imagine what is growing inside these tanks. Maybe another article for the reasons of our engines failing to start and perform as designed??