Pipeline pump can send water out because of centrifugal force. Before the pump works, the pump body and the inlet pipe must be filled with water to form a vacuum state. When the impeller rotates rapidly, the blades promote the water to rotate quickly. The rotating water flies away from the impeller under the action of centrifugal force. After the water in the pump is thrown out, the central part of the impeller forms a vacuum region. Under the action of atmospheric pressure (or water pressure), the water of Shuiyuan is pressed into the inlet pipe through the pipe network. In this way, continuous pumping can be realized. It is worth mentioning here that the centrifugal pump can be started only after the pump shell is filled with water before starting, otherwise, the pump body will be heated, vibrated, the water output will be reduced, the pump will be damaged (referred to as "cavitation") and the equipment accident will be caused!
There are many types of pipeline pumps. The common classification methods are as follows
According to the impeller suction mode, it is divided into single suction pipeline pump and double suction pipeline pump.
According to the number of impellers: single-stage pipeline pump and multi-stage centrifugal pump.
According to the impeller structure, it is divided into open impeller pipeline pump, semi open impeller pipeline pump and closed impeller pipeline pump.
According to the working pressure, it is divided into low-pressure pipeline pump, medium pressure pipeline pump, high-pressure pipeline pump and vertical pipeline pump.
Five key points for use of pipeline pump:
Test run: check whether the connecting parts are loose; Turn the coupling manually to rotate the rotor for several turns, and check whether the unit rotates flexibly, whether there is sound and uneven weight, so as to judge whether there is foreign matter in the pump or whether the shaft is bent, whether the seal is installed correctly, etc; Check whether the clean No. 20 lubricating oil in the sealing cavity is filled with 1 / 2 of the cavity space; Whether the surface of the pump unit is clean; Unit steering no-load test.
Manual start: fill the pump (for the first time), slightly open the outlet valve and start the motor. When the pressure rises and it is confirmed that the pump unit operates stably, gradually open the outlet valve to the working condition.
Operation inspection: when the pump operates normally at power frequency (frequency conversion), the readings of ammeter, voltmeter, inlet and outlet vacuum gauge, pressure gauge and flowmeter of the pump unit shall be regularly checked and recorded. Whether the vibration, noise and temperature rise of the unit are normal. There shall be no obvious aviation oil leakage at the shaft seal.
Normal shutdown: close the discharge valve to make the pump light load and stop the motor.
Emergency stop condition:
The indication of pump motor working ammeter is abnormal (too large or too few); The pump system makes abnormal noise.
The vacuum pressure gauge at the inlet and outlet of the pump indicate abnormally, the pump body vibrates greatly and makes abnormal noise, and the performance is seriously degraded.
The pump motor produces odor, aviation oil leaks from the shaft seal, and the bearing temperature exceeds 75 degrees.
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