The strength test of pneumatic ball valve should be carried out under the condition of ball half open.
① Sealing test of floating ball valve: put the valve in half open state, introduce test medium into one end and close the other end; rotate the ball several times, open the closed end when the valve is in closed state for inspection, and check the sealing performance of packing and gasket at the same time, without leakage. Then introduce the test medium from the other end and repeat the above test.
② Sealing test of fixed ball valve: before the test, rotate the ball several times without load, and the fixed ball valve is in the closed state. Introduce the test medium from one end to the specified value; check the sealing performance of the lead-in end with a pressure gauge. The accuracy of the pressure gauge is 0.5-1, and the range is 1.5 times of the test pressure. If there is no pressure drop phenomenon within the specified time, it is qualified; then the test medium is introduced from the other end, and the above test is repeated. Then, the valve is in the semi open state, both ends are closed, and the inner cavity is full of medium. Under the test pressure, check the packing and gasket, and there shall be no leakage.
③ Three way ball valves shall be tested for tightness at all positions.