The criteria of check valve selection

Check valve selection standard content is as follows:
In order to prevent medium counter-current, on the equipment, devices and pipelines should be install the check valve; Check valve is generally applicable to clean medium, should not be used in medium containing solid particles and viscosity is bigger; Generally on the level of nominal diameter of 50 mm pipe should be choose vertical lift pump protection valve; Straight-through lift check valve can only be in a horizontal pipe installation; For pump inlet pipe, appropriate chooses bottom valve, bottom valve installed in the pump only commonly imported vertical pipe runs, and the medium flow from bottom to top.
Lift is swing sealing good, fluid resistance is big, horizontal should be installed in horizontal pipe runs with vertical installed in vertical pipe runs; Swing check valve installation position is not restricted, it can be installed in a horizontal, vertical, or sloped pipe, such as installed in vertical pipe runs, medium flows from down to up; Swing check valves should not be made into a small-bore valves, can make high working pressure, can achieve 42 mpa nominal pressure, nominal diameter and can do a lot, the maximum can reach more than 2000 mm.
According to the shell and packing material can be applied to any working medium and any operating temperature range. Medium for water, steam, gas, corrosive medium, oil, medicine, etc. Working temperature range is between - 196-196 ℃; Applicable occasions is low pressure, large caliber and installations is restricted.
Gate valve installation position is not restricted, can be installed in a horizontal pipe road, also can be installed in vertical or inclined line; Diaphragm type check valve is suitable for easy to produce the pipeline water hammer, the diaphragm is a good way to eliminate medium upstream water hammer, it is generally used in low pressure pipeline under normal temperature, especially suitable for the water pipe channel, working temperature in a normal medium - 12-120 ℃, pressure MPa, the diaphragm type check valve can be larger caliber, DN biggest can reach 2000 mm or more.
Ball check valve is suitable for the low pressure pipe, can be made into large diameter; Spherical check valve shell material can be made of stainless steel, sealers of hollow spheres can wrap teflon engineering plastics, and so on the road at the pipe of general corrosive medium also can be used, working temperature between - 101-150 ℃, its nominal pressure 4.0 MPa, or less nominal drift diameter range between DN200-48 For non-compressible fluid with check valve when the choice must first to evaluate need closing speed, the second step is to choose can satisfy the need to shut down the type of check valve.
For compressible fluid in check valve selection according to non-compressible fluid check valves in a similar way to choose, if the medium flow field is very large, used for compressible fluid check valve can be used a speed reducer, if the medium flow continuous period of rapidly not stop and start, as the export of compressor, then use the lift check valve,slab gate valve.
Check valve shall determine the size of the response, the valve supplier must provide the size of the selected data, so you can find under a given flow when the valve is fully open valve size; For high pressure check valves under DN50mm, appropriate chooses vertical lift check valve and cut-through lift check valve; For low pressure under DN50mm check valve, appropriate chooses butterfly check valve, vertical lift check valves and diaphragm type check valve; For DN is greater than 50 mm, less than 600 mm high pressure check valves, swing check valve is used in the appropriate; For closing water hammer shock is small or no water hammer pipe, appropriate chooses slow closed gently swing check valve closed butterfly check valve.
Swing check valve function is used to prevent the backflow medium pipeline. Check valve belong to automatic valve class, open-close part by medium flow to open or close. Check valve is used only for one-way flow of medium pipeline, prevent medium return, in case of an accident. Production of check valve according to the American standard ANSI B16.34 design and manufacturing china strainer. Check valve before and after the medium pressure in a close to balance each other and see-saw state, flap disc frequently with seat, some brittle materials disc was broken. Prevention method is to use the disc check valve for ductile materials.