Effect of medium temperature changes on the pump's minimum flow rate
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I would like to ask the experts: If the temperature of the medium pumped by the pump is much lower than the pump’s designed temperature, can the pump operate properly at flow rates well below the minimum required level? For example: My company has a pump with a rated flow rate of 500 m3/h and a minimum flow rate of 204 m3/h. The normal operating temperature for this pump is 120 degrees, but currently the temperature of the fluid being pumped is around 25 degrees. The pump’s flow rate ranges between 70–150 m3/h. The pump has been in operation for about 2 years without any failures; its vibration and noise levels are within normal ranges. I would appreciate it if someone could explain this phenomenon. Thank you!
Given what you’ve described, I think the 204 m3/h figure you mentioned is likely the minimum flow rate when the pump is in operation, rather than the minimum flow rate specified during the pump’s design phase. It’s impossible for a pump to operate at its designed minimum flow rate, and in your case, temperature has very little impact
Is the minimum flow rate on the performance table the operating flow rate or the design flow rate?
It depends on which column in the data table it is in. If it is in the operating conditions column, then this minimum flow rate represents the lowest flow rate that actually occurs during the pump’s operation. If it is in the performance column, then this minimum flow rate indicates the lowest allowable operating flow rate for that pump. The minimum flow rate specified in the process requirements must be higher than the pump’s allowable minimum flow rate
Within the performance curve range of the pump, it is acceptable for the pump to operate for short periods of time. Your pump is operating within the range you mentioned; although this is not ideal, it will not cause damage to the pump, only an inefficiency in its operation.
The last edit to this post was made by luoheng116 on 2010-6-23 at 17:32. Reply to 1# designengineer: As long as the operating temperature is not too close to the critical temperature of the medium, temperature has little effect on flow rate. Pumps generally do not operate at low flow rates, as when the flow rate is low, the medium inside the pump circulates more slowly, which can lead to an increase in temperature and thus cavitation. Since the normal operating temperature of the pump is 120 degrees, and it is currently 25 degrees, a slight increase in temperature due to a lower flow rate (which generally won’t be significant) has little impact; it’s just a waste of energy