Terms and definitions:

(1)  Static pressure life test.

Under laboratory conditions, the valve under the action of medium pressure, from fully open to fully closed cycle operation test.

(2) The number of static pressure life tests.

Valve static pressure life test, can maintain the standard performance of the total number of switching cycles.

Test requirement:

1) The butterfly valve for static pressure life test should be sealed. And the performance of the butterfly valve should meet the requirements of GB/T13927.

2) The schematic diagram of the static pressure life test system is shown in the figure.

3) The test medium was normal temperature water. If air is used as the test medium, the rated pressure difference of the valve should be controlled during the opening of the test.

4) No matter what way the butterfly valve is operated, when the static pressure life test is carried out. The operating device equipped with it should be carried out the opening and closing cycle test together with the valve. Handle (wheel) directly driven or driven by the worm gear deceleration mechanism manual operation butterfly valve.

5) During the static pressure life test, the opening of the valve should reach more than 90% of its actual opening from the fully closed sealing position.

6) Static pressure life test, from the opening position to the closing process, the body cavity should be filled with media and pressure, medium pressure is 90% ~ 100% of the nominal pressure of the valve. After reaching the closed position, the outlet side of the butterfly valve should release the medium pressure. The butterfly valve is opened under the condition of differential pressure of the test medium. When the rated pressure difference of butterfly valve is required. The rated pressure difference should be used as the test pressure difference.

7) The sealed butterfly valve is controlled by the stroke position. And the closed position is controlled during the test. To close the sealed butterfly valve by torque, the test should be operated according to the maximum opening and closing torque measured by the butterfly valve test. The sealing of the butterfly valve should be maintained at each opening and closing time. But the operating torque should not exceed the torque produced by the operating handwheel equipped with the butterfly valve by one person or the operating torque specified in the product standard.

8) Repeat deviation of stroke position should be less than 1°. The repeated deviation of operating torque should be less than ± 5%.

9) In the process of static pressure life test, the sealing performance and operating torque should be checked once every 200 ~ 500 times of opening and closing cycle according to the characteristics of the sealing pair material. After the sealing performance is qualified, continue to test. The butterfly valve operated by hand can be adjusted if the operating torque changes. The butterfly valve operated by other operating mechanisms can not be adjusted.

10) If the installation position of the butterfly valve is required, it shall be installed in the required installation position. And to the valve requirements of the flow of installation, no flow requirements, any direction installation.

11) The record of the static pressure life test times should be recorded by electromagnetic counter through the signal provided by the life testing machine or the travel switch driven by electric, hydraulic, pneumatic or other electro-hydraulic gas linkage device.