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Some common problems and the solutions  for slurry pumps

Published on 2020/08/26

Slurry pump is a common machine that uses centrifugal force to increase the energy of solid-liquid mixed media. It is mainly used in mining, metallurgy, construction, and some other fields. As a common and practical auxiliary tool, slurry pumps may have some common problems during use, such as: flow instability, cavitation, and seal failure, which will lead to the problem of slurry pump leakage. 


And our engineers from Walker Machinery, who have rich experience and knowledge in the slurry pump, have concluded that problems and their solutions for you.

Question 1. How to solve the unstable flow of slurry pump?


There are roughly servals reasons may account for the unstable flow of the slurry pump:


  1. The suction pipe or bottom valve is leaking, or the water inlet is blocked, which is a common cause of insufficient flow. 


Solution: Check the air leakage source of the suction pipe and the bottom valve and block it in time, or clean the sludge or blockage at the water inlet.


  1. Too low voltage causes the slurry pump speed to decrease, resulting in insufficient slurry pump flow. 


Solution: Check the power supply voltage and adjust it properly.


  1. there is air leakage in the pipeline or there is air in the pump body, 


Solution: Discharge the air in the pipeline in time should solve the problem.


  1. The severe wear of the sealing ring or impeller will also result in unstable flow of the slurry pump. 


Solution: Check and replace the severely worn sealing ring in time.


  1. The depth of the bottom valve is insufficient, which causes air to enter when pumping. 


Solution: Adjusted the depth of the bottom valve according to the suction stroke of the slurry pump.


  1. Slurry or other debris is accumulating in the suction pipe cavitation that occurs in the slurry pump. 


If the slurry pump works normally for a period of time after starting, but the current gradually drops and the flow is obviously insufficient, this problem still occurs after restarting the normal operation for a period of time, mostly because the slurry or other debris is accumulating in the suction pipe. 


When it is more serious, there will be loud noises in the slurry pump and obvious vibration of the pump head. At this time, the front pool and suction pipe should be thoroughly cleaned, and the length below the elbow should be reduced, or a stirring device should be added to reduce The slurry settles.


Question 2. How to solve the cavitation phenomenon of slurry pump?


At a certain temperature, when the liquid pressure drops below the saturation pressure, boiling vaporization occurs. This is the characteristic of the liquid itself. At a certain temperature, the saturation pressure is constant, and it increases with the increase of temperature.


For centrifugal pumps such as slurry pumps, the suction pressure can be reduced to make the liquid suck into the pump. When the suction pressure is lower than the saturated air pressure corresponding to the water temperature, the sucked liquid will undergo a vaporization reaction. The bubbles formed by gasification gather at the lowest pressure position in the slurry pump, that is, the back of the blade above the impeller inlet. As the surrounding liquid flows outward, the impact of the liquid will cause noise and vibration. If this happens, the impeller will be eroded. damage.

slurry pump seal leakage

Generally speaking, the measures to solve the cavitation phenomenon are:


  1. Control the suction liquid surface pressure to prevent the liquid surface pressure from being too low.


  1. Control the flow rate of the suction port to make the slurry pump work under the specified beat volume.


  1. Appropriately reduce the installation height of the slurry pump.


  1. The suction valve is fully open, and the filter screen is cleaned frequently.


Question 3. How to solve the failure of the slurry pump seal?


In different operating stages, the reasons for the failure of the slurry pump seal are different, and then we will analyze them one by one.


  1. The slurry pump leaked during assembly


The slurry pump is prone to problems during the installation process. It is generally necessary to observe whether the slurry pump is leaking through a static pressure test. When the leakage is small, there is a problem with the moving ring or static ring sealing ring in the small shift. If the leakage is large, it is There are problems with the dynamic and static ring friction pairs. The leaking medium is sprayed along the axial direction, which is mostly the problem of the moving ring seal. If the leaking medium is sprayed around or leaks from the water cooling port, most of the static ring seals have problems. At this time, you should carefully observe and determine the problem and proceed in time Adjustment.


  1. Leakage during test operation of slurry pump


After the static pressure test, the reason for the leakage of the slurry pump is generally caused by the damage of the dynamic and static ring friction pairs. There are many reasons for this phenomenon, generally: axial force caused by abnormal phenomena such as cavitation, evacuation, holding pressure, excessive compression when installing the seal, too tight or too loose moving or static ring seals, There are reasons such as particles in the working medium entering the friction pair. The main solution is to re-disassemble and replace the seal.


  1. Sudden leakage during normal operation of slurry pump


In this case, a few are caused by normal wear or the service life of the slurry pump, but most are caused by changes in working conditions or improper operation and maintenance. The main reasons are: evacuating cavitation or holding the pressure for a long time, the actual output is too small, the sealing cooling water is interrupted, the operation is stopped for a long time and the car is restarted, the corrosive, polymerizable or gelling substances in the medium increase, and the slurry The temperature of the working environment of the pump changes drastically, and the working conditions are frequently adjusted. In the process of using the slurry pump, pay attention to the use specifications. The shaft seal water must be connected before use. The pump can be turned off after five minutes of stopping. If the pump is out of service for a long time, clean water and clean the pump cavity and mechanical seal before stopping the operation. , Manual cranking when restarting, prolong the service life of slurry pump.


Above we have summarized some common problems in the use of slurry pumps. In order to avoid problems during use, the use process of slurry pumps should be standardized, and regular inspections should be conducted to find out the cause and make timely decisions when abnormal conditions occur. Adjustments can ensure the normal use of the equipment and the normal operation of the plant.