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Analysis of the reasons why centrifugal pumps cannot pump water and solutions

Time of Release:

2022-08-18

There are many types of centrifugal pumps, and commonly used centrifugal pump products include: single-stage centrifugal pump, multi-stage centrifugal pump, and double suction centrifugal pump. Among these three types of products, only single-stage centrifugal pump has a certain self suction capacity, and the other two types of multi-stage centrifugal pump and double suction centrifugal pump do not have self suction pumping capacity. If the liquid level is lower than the pump, other water diversion methods must be used to pump water up, The common water intake methods are vacuum water intake or adding a water intake pipe at the pump inlet for water intake.

Analysis of the reasons why centrifugal pumps cannot pump water and solutions

  There are many types of centrifugal pumps, and commonly used centrifugal pump products include: single-stage centrifugal pump, multi-stage centrifugal pump, and double suction centrifugal pump. Among these three types of products, only single-stage centrifugal pump has a certain self suction capacity, and the other two types of multi-stage centrifugal pump and double suction centrifugal pump do not have self suction pumping capacity. If the liquid level is lower than the pump, other water diversion methods must be used to pump water up, The common water intake methods are vacuum water intake or adding a water intake pipe at the pump inlet for water intake.

  1、 The reason why a single-stage centrifugal pump cannot pump water

  Although a single-stage centrifugal pump has a certain self suction capacity, it is still necessary to ensure full sealing and no air leakage during the installation of the inlet pipeline. The reason why centrifugal pumps cannot pump water may be due to incorrect installation and use by the user. The correct installation and use method is to install a bottom valve on the suction pipe of the centrifugal pump at the bottom of the water tank. Before starting, the entire pump body and inlet pipeline need to be filled with water. Before starting, the outlet valve needs to be closed. After starting the centrifugal pump, slowly open the outlet valve. The self suction performance of each single-stage centrifugal pump varies depending on the model, When selecting a centrifugal pump, it is necessary to have a clear understanding of the NPSH of each single-stage centrifugal pump model in order to determine the effective self suction height of the pump.

  The reason why a single-stage centrifugal pump cannot pump water is that the self suction height may exceed the effective self suction height of the centrifugal pump, and the self suction height of conventional single-stage centrifugal pumps is within 3 meters. If the height exceeds this, a self suction centrifugal pump or a high suction head self suction pump with vacuum assistance should be selected. The reason why a single-stage centrifugal pump cannot pump water in use may also be due to blockage of debris in the pump chamber, impeller, bottom valve, pipeline, and other areas. If the seal of a single-stage centrifugal pump leaks, it can also cause the centrifugal pump to fail to pump water. The reason why the newly installed centrifugal pump cannot pump water may also be due to the incorrect rotation of the motor. If the rotation is incorrect, it is necessary to cut off the power and stop the machine before replacing any two power lines.

  2、 The reason why multi-stage centrifugal pumps cannot pump water

  Multi stage centrifugal pumps do not have self-priming ability. Many users install multi-stage centrifugal pumps in the same way as single stage centrifugal pumps by adding a bottom valve at the inlet. Before starting the pump, it is filled with water but cannot be pumped. In this case, only a water inlet tube or a water ring vacuum pump can be installed at the pump inlet. If it is necessary to choose a multi-stage centrifugal pump during the new procurement and selection stage, we can combine it with the vacuum pump to assemble a fully automatic vacuum auxiliary system according to the actual situation. First, start the vacuum pump. When the vacuum pump draws water up, then start the multi-stage centrifugal pump to achieve the effect of multi-stage centrifugal pump being able to self suction.

  3、 The reason why the double suction centrifugal pump cannot pump water

  The conventional double suction centrifugal pump belongs to the SH double suction centrifugal pump or SOW double suction centrifugal pump. Due to the special design of this pump, the pump itself does not have self suction capacity. Therefore, even if you install a bottom valve and fill it with water, the double suction centrifugal pump still cannot pump water. The solution is the same as the solution of multi-stage centrifugal pump not being able to pump water.
 


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