We all know that in the entire fire protection system, the fire pump can pressurize and transport fire water to meet the requirements of flow and head during emergency rescue. If the diesel fire pump is improperly set up, used, and maintained, it will inevitably affect the rescue and cause unnecessary loss of life and property. Therefore, diesel fire pumps must be carefully set up, used, and maintained.
Among them, the diesel fire pump can be self-driven without an external power supply. It is used as a backup fire pump in many places such as chemical plants, which is equivalent to a "double insurance" for fire safety. However, there are some special precautions for the commissioning and maintenance of diesel fire pumps, including: diesel fire pumps must not be reversed!
Regarding the problem of reversing diesel fire pumps, there have been factories that have had such erroneous operations before, which has caused more serious consequences.
A factory purchased two fire pumps of a certain brand, one driven by a diesel engine and the other by an electric motor. During the fire inspection, the diesel engine directly burned and exploded. Fortunately, there were no other accidents and casualties on the scene, and the losses were within a controllable range.
At that time, the diesel engine drive pump was tested on site as required, simulating the alarm functions of the control cabinet overspeed, low oil pressure, and high water temperature. The acceptance team tested the electric pump and inspected the diesel engine control cabinet. During the acceptance process, the electric pump started. At this time, the water in the electric pump flowed back to the diesel engine pump, causing the diesel engine to reverse and emit a lot of white smoke. The oil pipe valve was closed and the engine was shut down. This process lasted about 2 minutes. After standing, the technician disassembled the universal joint coupling. The pump rotated two circles and it could operate normally. No abnormal sound was found after manually turning the diesel engine for two circles. After several attempts to start the engine, the diesel engine started. At the beginning, the diesel engine ran all characteristic parameters and showed normal. After running for two or three minutes, an abnormal sound appeared. When the engine was about to stop to check the abnormal sound, the diesel engine housing broke, the crank flew out, and a large amount of oil leaked.
This example is to tell you why the cylinder body burst and the crank broke when the diesel engine was turned again after checking it later? The reason is that after the diesel engine is reversed, white smoke indicates that there is a serious lack of oil inside the diesel engine, or the friction of parts has generated high temperature, the crank has deformed and changed, and the phenomenon cannot be felt by manual turning. When running later, the high speed plus high load, the crank cannot withstand it, breaks, and pops out directly; or when running in reverse, the crank has broken inside the cylinder, and it collides with a certain part during high-speed operation and pops out directly.
The diesel engine usually used for diesel engine-driven fire pumps is a unidirectional rotating diesel engine and cannot be reversed. If the diesel engine is reversed, the carbon deposits accumulated in the exhaust pipe and the muffler are sucked into the cylinder, which will aggravate the wear of the cylinder, piston and piston ring; at the same time, the oil pump is reversed and cannot deliver oil to the lubrication part, causing the accident of burning the bearing and seizing the shaft.
