3, For Butterfly Valve

The pneumatic test of the butterfly valve is the same as the test of the globe valve. The test medium should flow into the valve from the inputting end when the test begins. Open the disc and close another end. Check the packing and other sealing parts weather it leaks after the pressure has been pumped up to the set value. Then close the disc, open the other end, check the sealing part of the disc. If no leakage happens, the valve is qualified. What is worthy to be mentioned is that the test is forbidden if the butterfly valve is used for regulating flow.

4.For plug valve

When the strength test of the plug valve is carried out, introduce the medium from one end while the other channels closed. Rotate the plug to each working position at a full open state one by one. the Valve Body is qualified if no leakage happens.

During the sealing performance test, the pressure in the chamber of the straight-through plug valve should be equal to the pressure in channels. Rotate the plug to non-working position, check from the other end. Then, rotate the plug 180 degrees, repeat the check;

The pressure in the chamber of the three-way or four-way plug valve shall be maintained equal to the pressure in the channel. Posit the plug at non-working positions in turns. Pump up the pressure from the right angle end. Check other ends simultaneously.

Before the test of the plug valve, it is allowed to apply a layer of non-acid thin lubricating oil on the sealing surface. The valve is qualified if there is no leakage and expanding drop. The test time of the plug valve could be shorter than other valves. It varies from 1 to 3 minutes according to its nominal diameter.

5.For Diaphragm Valve

During the strength test, introduce the testing medium from either end of the valve, then open the disc while the other end remains closed. Check the body and the bonnet of the valve after the pressure is promoted to the specified value. Then turn down the testing pressure for the sealing test. Close the disc and open the other end to check it. The valve is qualified if no leakage occurs.

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