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Six common faults of diesel engine fire pump and their solut

Article provenance：Hai Rui ZhonglianPopularity：Publication time：2020-03-25 08:48

Six common faults of diesel engine fire pump and their solutions

1. Diesel engine fire pump fails to start:

First, check the power supply of diesel engine fire pump: whether the connector is firm; whether the switch is tight; whether the fuse is blown; whether the three-phase power supply is equal. In case of disconnection, poor contact, fuse fusing and phase loss, the cause shall be identified and repaired in time. Secondly, check whether it is the mechanical failure of the diesel engine fire pump itself. The common reasons are: the packing is too tight or the impeller and pump body are stuck by debris; the pump shaft, bearing, leakage ring rust, serious bending of the pump shaft, etc. Remedial measures: loosen the packing, dredge the water tank; dismantle the pump body, remove debris and rust; dismantle the pump shaft to correct or replace it with a new one.

2. The supporting power motor of diesel engine fire pump is overheated:

The first is the reason for power supply: high or low voltage. Then the motor will overheat; the three-phase voltage of the power supply is asymmetric; the unbalanced three-phase voltage of the power supply exceeds a certain value; it will cause the winding to overheat.

The second is the cause of diesel engine fire pump: power mismatch, small horse pull, motor overload operation for a long time, so that the motor temperature is too high; motor start too fast, quota time is short or intermittent working system continues to work. The number of starts shall be limited, the thermal protection shall be properly selected and used according to the motor calibration quota.

The third is the reason of the motor itself: wrong connection, wrong connection of the shape into Y-shape, so that the temperature of the motor rises rapidly, the stator winding is short circuited, short circuited or partially grounded, and the part of the optical motor is overheated, the insulation is burnt when it is serious; the cage rotor is broken or defective. When the motor runs for 1 to 2 hours, the core temperature rises rapidly. If the ventilation system fails, check whether the fan is damaged, whether the rotation direction is correct, and whether the ventilation hole is blocked; bearing wear and rotor eccentric scanning make the rotor core rub out metal collision sound, and the core temperature rises rapidly. In serious cases, the motor smokes, even the coil burns.

The fourth is the working environment: the motor winding is wet or dust, oil and other attached to the winding, resulting in a low degree of insulation. The insulation resistance of the motor shall be measured, cleaned and dried; the ambient temperature is too high. When the ambient temperature is over 35 ° C, the inlet temperature is high, which will cause the motor temperature to be too high. Efforts should be made to improve their working environment. Such as shade.

3. Diesel engine fire pump heating:

Causes: the bearing is damaged; the clearance between the rolling bearing or bracket cover is too small; the pump shaft is bent or the two shafts are not coordinated; the tape is too tight; the oil is short or the oil quality is poor; the balance hole on the impeller is blocked, the impeller is unbalanced, and the thrust is increased to one side. Troubleshooting: replace the bearing; remove the rear cover, and install a washer between the bracket and the bearing housing; check the concentricity of the pump shaft or adjust the concentricity of the two shafts; properly loosen the tightness of the tape; fill the cleaning grease, which accounts for about 60% of the bearing clearance; eliminate the blockage in the balance hole.

4. The flow of diesel engine fire pump is insufficient:

This is because: the power speed does not match or the belt slips, the speed is low; the installation angle of the axial flow pump blade is too small; the head is insufficient, the pipeline is too long or the pipeline has a right angle bending; the suction stroke is high; the bottom valve, the pipeline and some impellers or impellers are defective; the water leakage of the outlet pipe is serious. Troubleshooting: restore the rated speed, remove the belt grease, adjust the belt tightness; adjust the blade angle, reduce the installation position of the diesel pump, shorten the pipe or change the bending of the pipe; seal the leakage of the diesel pump and compress the package; remove the blockage and replace the impeller; replace the leakage ring and prevent the leakage.

5. The diesel engine fire pump is unable to absorb water:

The reason is that there is air in the pump body or there is gas accumulation in the intake pipe, or the bottom valve is not closed tightly, so it is unable to flush the water, the packing of vacuum pump leaks seriously, and the gate valve or flap valve is not closed tightly. Troubleshooting: first, raise the water pressure, then fill the pump with water, and then start it. At the same time, check whether the check valve is tight and whether there is leakage in the pipeline and joint. If leakage is found, paint the joint with lubricant or ready mixed paint after disassembly and tighten the screw. Check the oil seal ring of the diesel engine pump shaft, and replace it with a new one if it is seriously worn. Leakage of water or air in pipes. It may not be possible to tighten the nuts during installation. If the leakage is not serious, it can be applied with cement at the place of air leakage or water leakage, or mixed with asphalt oil in the cement slurry. Temporary repairs can be made with wet mud or soft soap. If water leaks at the joint, use a wrench to tighten the nut. If the leakage is serious, the broken pipe must be reassembled and replaced. The pressure head can be lowered, and the nozzle of the diesel pump is pressed into the water for 0.5m.

6. Diesel engine fire pump vibrates violently:

The reasons are: the electric rotor is unbalanced, the coupling is bad, the bearing is worn and bent, the rotating parts are loose and cracked, the pipeline support is not firm, etc. It can be adjusted, repaired, reinforced, straightened and replaced. ..

The above conditions are common causes of diesel engine pump failure, not all of them. In practice, for the reason of practical analysis, we should follow the principle of "first outside, then inside", instead of blind operation.

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