We use the pressure well above the piston and the pressure well below the piston. The piston and valve are one-way valves that allow the air to go up, not down. When the piston is on the journey, when the valve is opened, the air under the pipe can be pumped to the top of the chamber. When the piston is down, when the valve is closed, it will come out from the edge of the piston. In this way, the air under the pipe will be vacuumized in water, under the action of atmospheric pressure, which has been formulated, However, sometimes the sealing is not good, and the piston will leak from the outside when it goes up. When it goes down the well, the air in the piston chamber may leak from the valve into the courtyard below, so the vacuum pipe is difficult, because the water has a certain sealing effect and the improved rapid pumping of water, and the diversion effect is sealed.

In fact, in many places, the water level of the high water pressure well can not be pumped in the upper water.

Valve water-free test press: do you know the pressure test methods of various valves

Generally, water is used as the pressure test medium for the valve, and the upstream of the valve is connected with the pressure test pipeline (flange or thread). After the valve is closed, the upstream water is injected to increase the pressure to the specified pressure and the pressure remains unchanged according to the pressure test regulations. Observe the sealing state at the downstream of the valve. If there is leakage, collect and measure it, that is, the amount of leakage within the specified time. For valves with high sealing requirements, compressed air is used as the medium for pressure test. During the pressure test, the valve shall be immersed in water. If there is leakage, bubbles will be seen in the water, and then the gas gathering and drainage method can be used to collect bubbles. Similarly, the bubble shall be measured to obtain the leakage amount within the specified time.