Is the excessive actual discharge volume of shielded pumps related to the density of the medium? I’m asking all the experts for help in answering this question; I’d be extremely grateful! ! !
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The liquefied gas loading pump on our side is a canned motor pump, with the following specifications: flow rate of 100 cubic meters per hour, head of 100 meters, power of 45 kilowatts, and current of 95 amperes. During actual loading, the calculated volume is around 150 cubic meters, but the current does not exceed the rated current. If the displacement is controlled to within 100 cubic meters by adjusting the valve, the current will be very low. Is this situation normal? Is it because the pump was calibrated with clean water at the time of manufacture but is used on-site to transport liquefied gas (with a density of about 0.52)? If the pump operates in this manner for an extended period of time (with a flow rate of 150 cubic meters per hour), could it cause any damage to the pump? I earnestly ask all the experts to help answer my questions; thank you!
Power is also related to head; with a low outlet back pressure, the flow rate can easily exceed the rated value without the current going over limit. . The motors of shielded pumps are custom-made, based on design specifications; they are not designed for use with plain water
It is best to have the performance curves provided by the manufacturer, as this makes it easier to identify issues.
If the flow rate is too high while the motor current remains within limits, it’s definitely because the head pressure has decreased. As long as this meets your requirements, there’s no problem – after all, a higher flow rate leads to better efficiency.
Thank you! The manufacturer says that the parameters on the nameplate are calibrated based on clean water.
It’s a pump from 10 years ago; I’ll look again to see if there are any performance curves available! Thank you!
As long as it can meet the on-site requirements, the main concern is any potential negative impact on the shielded pump. Thank you!
It is believed that operating for a long time under the conditions described by the poster, with the current not exceeding the rated value and no abnormalities such as excessive vibration, temperature issues, or unusual noises in the pump, will allow it to continue functioning without causing any adverse effects on the pump.
Unless you specifically request it at the time of purchase, manufacturers generally match the motors to a clean water medium for hydronic transport; therefore, the motors used for shielding purposes are of larger size. If it is not used at the rated operating point for an extended period of time, the axial force will become uncontrollable (unless 150 cubic units is specified as the operating point at the time of purchase). A high axial force reduces the service life of the bearing surfaces, and close monitoring is necessary; if the rotor experiences excessive axial displacement, it can cause wear on mechanical components such as impellers, resulting in significant losses!