When the vacuum pump is used as a vacuum pump for water diversion, the water cannot be pumped due to improper operation. What is the reason why the vacuum pump cannot pump water?

(1) The number of revolutions of the vacuum pump is insufficient or reversed, which will cause the motor to burn.

(2) The circulating water is not introduced or the water pipeline is blocked, and the valve is not opened.

(3) The amount of circulating water is too large, and the circulating water is returned.

(4) There is air leakage in the sealing box of the lift pump (commonly known as packing), the water supply pipeline or flange, etc.

(5) The outlet valve of the lift pump is not closed tightly.

(6) The vacuum pump plate leaks air, and the pump is severely worn or damaged.