The Structure of Check Valve

25. Mai 2017 à 08h27, catégorie : G?n?ral




The structure, principle and installation notice of check valve
Check valve is also known as reverse flow valve, back pressure valve, one-way valve. This kind of valve is automatically opened and closed by the flow and the medium of the pipeline itself. It belongs to an automatic valve.

The check valve is used for the piping system, the main function is to prevent the medium from flowing back, to prevent the pump and its drive motor from reversing, and to discharge the medium in the container.

The check valve can also be used to provide a supply to the auxiliary system where the pressure may rise above the pressure of the main system. The check valve can be applied to pipelines of various mediums according to the different materials.

Check valve is installed in the pipeline, which becomes one of the components of the complete fluid pipeline, the valve will open and close the process by which it is affected by the system transient flow state; in turn, the valve closure have made effect on the fluid flow state.

The working characteristic of the check valve is that the load varies greatly, the opening and closing frequency is small, the input is closed or opened, the cycle is very long, and the movement of moving parts is not required.

But once again "switching" requirements, you must move flexibly, this requirement has more severe and more common mechanical movement. As the valve is in the most practical use, has rapid qualitative determination of closure, and in the moment of valve closure, the medium is the direction of flow, with the valve closed, medium speed is from maximum back to zero quickly, and the pressure is rapidly increased, which is likely to damage the pipeline system water hammer phenomenon.

The water hammer of the check valve is more prominent for the high pressure pipeline system in which multiple pumps are connected in parallel. Water hammer is a pressure wave to a transient flow in a pressure pipe. It is a hydraulic shock caused by the pressure rise or fall, caused by the change of fluid velocity in the pressure pipe.

The physical causes are fluid compressibility, fluid motion inertia and pipe elasticity. In order to prevent water hammer in pipes hidden for many years, people designed with a number of new structures, new materials for the valve, in order to ensure the performance of check valves at the same time, minimization of the impact of water hammer have made gratifying progress.

Check valves include many types, such as ball check valves and butterfly check valves. Butterfly check valves include swing check valves and lift check valves. The swing check valve has a hinge mechanism and a gate like valve free against the inclined seat surface.

In order to ensure that the valve can reach the appropriate position of the seat surface at any time, the disc is designed in the hinge mechanism so that the disc has enough swing space to make the disc real and comprehensive contact with the valve seat. The disc can be made of metal or leather, rubber, or synthetic coverage, depending on performance requirements. The swing check valve is almost completely open and the fluid pressure is almost unimpeded, so the pressure of the valve is relatively small. The lift check valve is located on the valve seat and the sealing surface of the valve seat.

The installation and use of check valves shall be noted:
1, vertical lift check valve should be installed on the vertical pipe.
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What Should Be Paid Attention to During Installing Ball Valve

22. Mai 2017 à 08h02, catégorie : G?n?ral




The installation of ball valve directly affects the service life of the ball valve:
1) The installation position, height, import and export direction must comply with the design requirements, and the connection should be firm and tight.
2) All kinds of manual valves are installed on insulated pipes, the handle shall not be downward.
3) The valve must be installed before the appearance of inspection, valve nameplate should be in line with the existing national standards, "general valve signs" GB 12220 requirements.

The work pressure is greater than 1 MPa, should be installed before the strength and tight performance test. Strength test, the test pressure is 1.5 times of the nominal pressure, duration time is not less than 5min, the valve shell and filler should be no leakage qualified. Tightness test, the test pressure is 1.1 times of the nominal pressure; test pressure in the test duration should meet the requirements of GB 50243 standards, the valve seal surface leakage is qualified.
4) The valve flange and the pipeline flange, are according to the design requirements of the pipeline installed gasket.
5) With the drive mechanism of the ball valve, according to the instructions of the product installation.

The working principle of ball valve:

The opening and closing parts of the ball valve is a sphere, and the ball rotates around the center of the valve body to achieve the opening and closing of a valve.

Ball valve features:
1) Flow resistance is small;
2) The structure is simple;
3) Small in size and light in weight;
4) The sealing surface of the ball valve is made of plastic and sealed well;
5) Easy to operate, quick opening and closing, convenient for long-distance control;
6) Easy maintenance, sealing ring is usually movable, easy to disassemble and change;
7) Fully opened or fully closed, the ball valve and valve seat sealing surface and dielectric isolated, the media will not cause the sealing surface of the valve erosion.

The use of ball valves:

It is used in a place on a low pressure or small caliber pipe to cut water flow and change the flow of water, it can be rapidly opened and closed.

For more information about sanitary valves, please visit http://www.adamantvalves.com/sanitary-ball-valves.html





Applications of Clip Type Check Valve

22. Mai 2017 à 07h49, catégorie : G?n?ral




Check valve is installed in the pipeline system, the main role is to prevent media backflow, check valve is a kind of the media to open and close the automatic valve. The clip type check valve applies to nominal pressure PN1.0MPa~42.0MPa and Class150~25000; nominal diameter is DN15~1200mm and NPS1/2~48; work temperature is -196~540 degrees of various pipelines, used to prevent medium flow back. By choosing different materials, it can be applied to many mediums such as water, steam, oil, nitric acid, acetic acid, strong oxidizing medium and uric acid.

Main material for clip type check valve:
Are carbon steel, low temperature steel, dual phase steel, titanium alloy, aluminum bronze, Inconel Seoul, SS304, SS304L, SS316, SS316L and other metal materials.

Standard and specification for clip type check valves
1, design and manufacture: API594, API6D, JB/T8937, JB/T3595,
2, structure length: API594, API6D, DIN3202, JB/T8937, ANSI/ASME, B16.10
3, pressure, temperature levels: ANSI, B16.34, DIN2401, GB/T9124, HG20604, HG20625, SH3406, JB/T74
4, test and test: API598, JB/T9092, GB/T13927
5, piping flanges: JB/T74~90, GB/T9112-9124, HG20592~20635, SH3406, ANSI/ASME, B 16.5, DIN2543-2548, GB/T13402, API605, ASMEB16.47

Function of clip type check valve
Check valve relies on the flow of the media itself and automatically open and close the valve flap, used to prevent media backflow valve, also known as reverse flow valve and back pressure valve. The check valve belongs to an automatic valve, whose main function is to prevent the backflow of medium, prevent the reverse of pump and drive motor, and release the container medium.

The structural features of the check valve:
1, The length of the structure is short, and the length of the structure is only 1/4~1/8 of the traditional flange check valve
2, Small in size, light in weight and 1/4~1/20 in weight only with traditional flanged check valves
3, the valve closed fast, water hammer pressure is small
4, horizontal or vertical pipes can be used, easy installation
5, the flow passage is unobstructed and the fluid resistance is small
6, sensitive action and good sealing performance
7, valve stroke short, close, small impact
8, The whole structure is simple and compact, and the shape is beautiful
9, long service life and reliable performance

The check valve is used in the water supply system, the water pump is to prevent the impact of the high pressure water on the impeller of the pump. System in operation, for some reason, when the water pump suddenly stops running, the pressure inside the pump disappears, and the high-pressure water connected with the water pump outlet will reverse flow backwater pump. When the pump outlet is equipped with a check valve, it will be closed immediately to prevent the high pressure water reverse flow backwater pump.

The function of the check valve in the hot water system is to prevent hot water from flowing back into the pipe. If it is a PVC tube, it is likely to blow up the pipe and may even injure people, especially in the solar water heater system.

For more information about sanitary valves, please visit http://www.adamantvalves.com/sanitary-check-valves.html