The problem of import pressure being greater than export pressure
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Our company has a hot water circulation pump used to circulate water at 170 degrees Celsius, with a designed head of 28 meters. Currently, the pressure at the pump inlet is shown as 0.9 Mpa, while the outlet pressure is shown as 0.6 Mpa. The customer reports that they are unable to pump in the material. I would like to ask everyone what could be the reason for this – is it related to the pump?
Isn’t it showing 60 meters for the outlet? Is there maybe a valve at the outlet that isn’t open?
The inlet is blocked, or the impeller channels are blocked, or there is air in the pump that hasn’t been removed
Head is an approximate value of the pressure difference between the inlet and outlet, right?
It has been checked; there is no blockage in the impeller or at the inlet, no gas is present inside the pump, and there is also no pressure drop at the inlet or outlet
I’ve never encountered anything like it; this pump is truly amazing. Its gauge pressure is 0.9 MPa (absolute pressure of 1.0 MPa), and its boiling point is 179 degrees； Gauge pressure of 0.8 MPa (absolute pressure of 0.9 MPa), boiling point of 175 degrees ； ； Gauge pressure of 0.6 MPa (absolute pressure of 0.7 MPa), boiling point of 165 degrees ； If the pressure is too low, water vapor will become saturated; it may seem as though the inlet temperature is too high, with the material almost in the form of water vapor. If the operation is not proper or if the temperature is too high, air can form, preventing liquid from entering ； At the same time, no hot water comes out from the outlet, or only a small amount of liquid does; as a result, the temperature remains at 170°, but the amount is very small – it’s in gas form, with an increased volume, and the pressure drops rapidly ； It is recommended to consider adding a cooling device at the hot water inlet, or using instruments to adjust the pressure inside the tank to a higher level ； This is my own analysis; it is recommended to consult the manufacturer. This type of high-temperature pump is relatively rare, and it is more commonly used in boiler steam systems. The manufacturer likely has plenty of data on such cases and should be able to provide a solution ；
Is the impeller installed in the wrong direction? Or reverse the motor?
Thank you, we are still investigating it for now.
No, even if it’s installed backwards, there shouldn’t be high inlet pressure
With an inlet pressure of 0.9 and a head of 28 meters, an outlet pressure of 1.2 is appropriate. Is it because the pump is installed at a high position?
I’m not sure if it’s a centrifugal pump; the inlet pressure is 0.9 MPa. Even when the pump isn’t running, the outlet pressure is at least 0.9 MPa. Is the gauge broken now that the pressure is 0.6 MPa?