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Check Valve Good Sealing, Fluid Resistance
Jul 04, 2017

Check valve in a lot of work at the same time, its product quality is very important. So that the normal operation of the check valve is the guarantee of continuous work, if the leisure time through a variety of test methods for the quality of the check valve to achieve the purpose of safe work. So how does the check valve detect?

We generally divide the easiest way to check the check valve into three steps:

First, open the check valve access, water (or kerosene) filled the valve chamber, and boost to the strength test requirements of the pressure, check the valve body, bonnet, gasket, filler with or without leakage.

Second, off the dead valve, in the side of the check valve to the nominal pressure, from the other side to check whether the leakage.

Third, the check valve will be reversed, the opposite side of the test. Through the above three simple steps can be analyzed to check the basic working state of the check valve is abnormal.

Of course, there are more complex test methods, the following method is pointed out that the more complex for the potential problems, the basic steps can be divided into two steps:

First, the check valve test pressure Nominal pressure from 0.4Mpa-32Mpa, these commonly used pressure valve, the valve strength test pressure for its nominal pressure of 1.5 times. Valve seal test pressure, equal to 1.1 times the nominal pressure.

Second, the check valve test bench usually has a compression part above, there is a connection with the test pump connected to the pipeline. The valve will be pressed, the test pump work, from the pressure test pump on the pressure gauge, you can read the pressure to withstand the valve number. Electric valve test pressure water, the valve to the air drained. The upper platen of the test bench has an exhaust hole and is opened and closed with a small valve. The sign of the air is that all the ones out of the vent are water. Close the vent and start boosting. The step-up process should be slow, do not be sharp. To achieve the required pressure, to maintain 3 minutes, the pressure does not change to qualified.

1In order to prevent the media against the current, in the equipment, equipment and pipelines should be installed on the check valve;

2Check valve is generally suitable for clean media, should not be used for containing solid particles and viscosity of the larger media;

3Generally in the nominal through the 50mm level of the pipeline should be used on the vertical lift check valve;

4Straight-through lift check valves are available on both horizontal and vertical piping;

5For the pump inlet pipe, should use the bottom valve, the bottom valve is generally only installed in the pump inlet vertical pipe, and the media from bottom to top flow;

6Lift type swing good seal, fluid resistance, horizontal should be installed in the horizontal pipe, vertical installed in the vertical pipe;

7The position of the swivel check valve is not restricted and can be mounted on a horizontal, vertical or inclined line, as in a vertical pipe,

8Swivel check valve should not be made into a small diameter valve, can be made of high working pressure, PN can reach 42MPa, and DN can also be great, the maximum can reach more than 2000mm. Any working medium and any operating temperature range can be applied depending on the material of the housing and the seal. Media for water, steam, gas, corrosive media, oil, drugs, and so on. Medium operating temperature range between -196 - 800 ℃;

9The application is low-pressure large-caliber, and installation occasions are limited;

10The mounting position of the butterfly check valve is unlimited and can be mounted on a horizontal line or on a vertical or inclined line;

11Diaphragm check valve for easy to produce water on the pipeline, the diaphragm can be a good way to eliminate the media when the counter-current water hammer, it is generally used in low-pressure room temperature pipe, especially for water pipes, the general medium operating temperature -12--120 ℃ between the working pressure <1.6MPa, but the diaphragm check valve can be larger diameter, DN can reach more than 2000mm;

12Ball check valve for low-pressure pipeline, can be made of large diameter;

13Spherical check valve shell material can be made of stainless steel, the seal of the hollow sphere can be wrapped in PTFE plastic, so in the general corrosive medium can also be applied to the pipeline, the working temperature of -101-150 ℃ Between the nominal pressure ≤ 4.0MPa, the nominal pass through the range between 200-1200;

14For a non-compressible fluid check valve, the first step is to evaluate the required closing speed. The second step is to select the type of check valve that may meet the required closing speed.

15The choice of a check valve for compressible fluids can be selected in a similar manner to the non-compressible fluid check valve. If the medium flow range is large, the check valve for compressible fluid can be decelerated Device, if the medium flow is not continuous to stop and start, such as the compressor outlet, then use the lift check valve;





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