Vertical multi-stage centrifugal pumps cannot draw water when under negative pressure
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The water pump model 65DL*9 functions properly for pumping water at normal temperature and under a negative pressure of -25 kbar. When the water temperature reaches 55°C and the negative pressure is -75 kbar, water cannot be pumped out; I ask all fellow divers for their understanding!
The water temperature is 55°C, the saturated vapor pressure is 15 kaA, and the negative pressure is -75 kbar; adding these together gives 90 kPa, while one atmosphere equals 101 kPa. 101-90=11 kPa, which is equivalent to a head of 1 meter. The pump also requires a NPSHr of more than 1 meter. How can it be used anymore? There’s no way of pumping water up.
Under the same operating conditions, some pumps function properly while others experience cavitation – what is the reason for this?
It’s impossible to ensure that the cavitation head of pumps is exactly the same
In other words, under the conditions of -0.09 MPa and 30 degrees, the multi-stage pump is able to pump water out.
How was it calculated? Could you provide some relevant materials? :handshake
It’s just about calculating the net positive suction head of the device