As the transmission and pressurization device of water source, water pump plays an important role in water supply system. Some failures often occur in the use of water pumps, and most of the failures are caused by improper use. The summary of years of practice -- 10 wrong use methods of water pumps, for your reference.
Overload
Whether it is flow, pressure or speed, excessive deviation from the rated design point for a long time may lead to increased pump load. For example, the maximum full open power of centrifugal pump may shorten its service life, or even "sudden death".
Difficult medium suction
1. The inlet liquid level is too low, which is easy to produce eddy current and suck in air, resulting in cavitation and lower flow head
2. The water inlet pipe or water inlet is blocked by foreign matters, resulting in the decrease of flow head
3. As the medium temperature increases, the vaporization pressure of the medium increases, and the cavitation allowance decreases, resulting in the reduction of the suction range
4. The inlet pipeline is unreasonable (for example, there are too many inlet pipe bends and the pipe diameter is smaller than the pump inlet), the pipeline loss increases and the cavitation allowance decreases, which is easy to cause cavitation erosion
5. As the altitude of the pump installation increases, the atmospheric pressure decreases, and the cavitation allowance decreases, resulting in lower suction lift
Only the valve is closed and the water pump is powered on
Except for the automatic pump and intelligent pump, the ordinary water pump operates under the closed valve condition for a long time without any bypass. The energy consumption of all systems is wasted on "heating" water, resulting in pump cavitation, unstable operation of the pump, and even accidents.
Corrosion
The conveyed medium corrodes the flow passage parts, mechanical seals, etc. For example, hydrochloric acid corrodes stainless steel, hydrofluoric acid corrodes silicon carbide, etc.
Note: the corroded surface will have numerous pinholes of different sizes, like the surface of the moon.
Abrasion
The liquid containing solid particles is transported, and the flow passage parts such as pump chamber and impeller are continuously scoured, so that the service flow and head of the pump are reduced and the service life is shortened.
Note: when the abrasion is serious, the abraded surface will produce fish scale pattern.
Pump body expansion crack
Because the outlet is blocked or the inlet pressure is too high, or the liquid in the pump cavity is frozen at low temperature, the actual pressure in the pump cavity is much higher than its pressure, and finally the pump body cracks.
Vibration
The water pump is installed on a rigid foundation, lacking vibration reduction measures, or the foundation is too weak to provide sufficient strength. The water inlet and outlet pipelines were lack of support, which eventually led to uneven stress on the unit and restrained the running vibration of the water pump. The pump was like jumping on a trampoline.
Damp
1. The onshore pump is in a humid environment for a long time or the mechanical seal fails, and the leaked liquid splashes to the unsealed part of the motor.
2. The mechanical seal and seal of the submersible pump are invalid, the cable is not sealed, the water pump enters the moisture or the cable falls into the pool in a humid environment, causing the liquid to invade the motor cavity.
Note: if there are water stains and condensation beads in the motor, and the insulation resistance is less than 50 megohm, it is regarded as damp.
Irregular inspection
The water pump never received enough "care", did not check and maintain regularly according to the requirements of the manual, and changed the mechanical seal irregularly. The iron pump and aluminum pump did not repaint the pump, and did not check the vibration, so that the pump went from "minor disease" to "major disease".
Poor heat dissipation
1. The submersible electric pump motor is exposed to the water surface for dehydration operation, or trapped in sludge, which makes the motor heat dissipation slow and easy to burn down. In particular, there is a risk of explosion due to poor heat dissipation of the oil filled motor.
2. The onshore pump is installed at every corner or in a closed box. The fan cannot circulate the surrounding air, resulting in poor heat dissipation of the motor.
