Will the pump get damaged if it operates at minimum flow?
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Will closing the pump outlet completely and allowing only minimal backflow to pass through damage the pump?
When the outlet valve of the pump is closed, if the pump runs for too long, it will cause the pump body to heat up, which is detrimental to the pump.
It won’t get damaged for now, but over time it will still affect its service life
Closing the pump outlet completely and allowing only minimal backflow will definitely damage the pump, especially harming the seals
Our facility has experienced accidents in which the operation of crude oil pumps at low flow rates led to coking of the furnace tubes
Personal opinion: With the pump outlet completely closed and only the minimum amount of backflow allowed, theoretically, this should not cause any damage to the pump. However, it cannot run for too long, as in that case some of the medium remains inside the pump, causing the temperature to keep rising; this can even lead to vaporization and damage to the pump.
It’s mainly a matter of time; I agree with the consultant – energy is conserved. Think about what electricity can be transformed into. If the outlet valve isn’t opened, it can only become heat energy.
All of the energy is converted into heat, causing the temperature of the pump to rise
The pump should still be stopped; it saves electricity and protects the equipment.
It should be feasible in the short term; in the long term, it’s certainly detrimental to the pump, as the overheating and vaporization of other substances inside the pump over time is definitely not good for it
As long as the temperature rise does not exceed the requirements specified in the pump’s manual and those of the medium, there is no problem. This post was last edited by ddfmy on 2009-3-29 22:04]
This phenomenon occurs in our company as well. The outlet valve of the pump is opened only slightly; over time, this leads to cavitation and vibration in the impeller, as well as damage to the mechanical seal.
One of the functions of the minimum flow line of a centrifugal pump (especially high-pressure centrifugal pumps) is to protect the pump in case of abnormalities in the process system; it should not operate when the outlet valve is closed. Although it is theoretically feasible, in practice accidents can easily occur due to reasons such as medium vaporization.
It’s not good for the pump itself, nor is it good for the motor. When operating at low load for extended periods, the pump generates heat, as does the motor. If process requirements dictate it, it is highly recommended to use variable frequency control. The effect will be absolutely amazing.
The minimum flow line is there to protect the pump from damage at the lowest flow rate; with the outlet valve fully closed and the minimum flow line activated, the pump should be safe.
With the outlet valve closed, the minimum reflux valve should ensure an opening degree of over 85%, as the design of the minimum reflux line generally includes a certain margin. If there is flow in the return pipe, it’s easier to control. As long as the flow rate is not below the pump’s minimum flow rate, it will not cause damage to the pump; however, prolonged operation will lead to an increase in the temperature of the fluid being transported and of the pump itself, which can result in cavitation in severe cases. As a supplementary point, this is not conducive to energy conservation and reduction of consumption.
With the pump outlet completely closed, it should not cause any damage to the pump. However, if it runs for a long time, some liquid remains inside the pump, causing the temperature to keep rising; eventually, vaporization occurs and this damages the pump
If it runs for a long time, it will cause the pump body to heat up, especially leading to damage to the seals.
Based on our factory’s experience, this will definitely cause an increase in the temperature of the pump body as well as the circulating liquid; operating it for extended periods can also lead to damage to the seals.
The minimum reflux flow rate of the pump is a protective setting intended for safety reasons. It is acceptable for short-term operation, but long-term use will lead to the heating problems of the pump body and motor mentioned by those upstairs.