How does the Fire-Fighting Pump preheating system work?

1. Constant Temperature Monitoring
A temperature sensor built into the control cabinet monitors the cooling water temperature in real time. When the water temperature falls below 40°C (or the unit's set lower limit), a preheat command is automatically issued.
2. Electric Heating
A 220V immersion electric heater (or external plate heater) directly heats the cooling water circuit. With a power output of 1–2 kW, it can raise the water temperature to approximately 45°C in 20–40 minutes.
3. Synchronous Oil Circuit Insulation
Some models utilize a 50W–100W heating pad on the oil sump in addition to heating the water jacket. This reduces oil viscosity and reduces cold start wear.
4. Dual Energy Guarantee
The preheating system is powered by the mains electricity. If the mains power is lost, the diesel engine's 24V battery, via an inverter, provides power, ensuring uninterrupted preheating. 5. Fire Alarm Interlock
Once the control cabinet receives a fire alarm signal, the preheating power supply is immediately cut off, and the diesel engine instantly enters the "ignition-speed increase-load" mode. The entire process takes 5–15 seconds.
6. Daily Self-Inspection
The system is powered on for 10 minutes daily to self-check the heater, sensors, and relays for proper function. A "preheating normal/abnormal" notification is displayed on the control panel to prevent malfunctions at critical moments.