No vacuum pads for high capacity centrifugal pump.

The centrifugal pump does not suck itself when the pump body and the suction pipe are full of air: the pump wheel in the gas only creates a very small pressure gap so that the water does not rise. With a large pump, the suction pipe is long or placed higher than the water level, the hand-putting of the prey water is no longer practical, and the popular solution is the vacuum suction for the suction pipe and the pump cover.

Why Use Fluid Pump for Prey

The gas to suck is the air saturated with steam, and when the prey is finished, the water can be pulled into the vacuum pump. The liquid ring pump can withstand both situations: the water entering only increases the amount of liquid in the ring, without causing damage as with the dry wing pump.

Calculate the time.

V is the volume to be sucked and S is the effective suction speed of the vacuum pump. The time to pull the pressure from p0 to p is approximately t = (V/S)·ln(p0/p). For example, V = 3 m3, S = 0.6 m3/min, pulling from 1.013 mbar to 400 mbar takes about 4.6 minutes.

The feet do not need to reach.

Each meter of water column corresponds to approximately 98 mbar. In order for water to rise to the pump center 5 m higher than the water surface, the absolute pressure in the pump body must fall below approximately 520 mbar, not counting the loss in the suction pipe.

Common mistakes

• The leakage of air on the flanges, glaciers or debris of the main pump causes unusually long prey times.
• Lack of separator or flue valve: water following the suction pipe runs directly into the vacuum pump.
• Do not disconnect the prey pump after the main pump has reached pressure, making the vacuum pump run in vain.