22 tips for selecting check valves

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　　Check valve (One-way valve): A check valve is also known as a non-return valve, single-flow valve, one-way valve, or reverse-stop valve. Its function is to ensure that the fluid in the pipeline flows in one direction only, preventing backflow. The foot valve on the water pump’s suction pipe also belongs to the category of check valves. Check valves belong to automatic valves. Pressure: 1.6~25 MPa/Class 150-2500/2.0-42.0 MPa; Operating temperature: -29~+550°C. Common materials include cast steel WCB, cast iron HT200, HT250, QT350, QT450, alloy steels WC6, WC9, CN7M; stainless steels include CF8 (M) and CF3 (M). Forged steel includes A105, F304(L), F316L, etc. It is suitable for use in pipelines in various industries such as petroleum, chemicals, pharmaceuticals, fertilizers, and power generation, under different operating conditions; the applicable media include water, oils, steam, acidic substances, etc. It is a valve that controls the one-way flow of the medium within the pipeline, used to prevent backflow of the medium in the pipeline. 　　The following are 22 tips from Huaguang Valves regarding the selection criteria for check valves: 1. To prevent the medium from flowing in reverse, check valves should be installed on equipment, devices, and pipelines ； 　　2. Check valves are generally suitable for clean media and should not be used with media containing solid particles or high viscosity ； 　　3. Generally, vertical lift check valves should be used on horizontal pipes with a nominal diameter of 50 mm ； 　　4. The direct-acting lift check valve can only be installed in horizontal pipes ； 　　5. For the inlet pipeline of the water pump, a foot valve is advisable; such valves are generally installed only on vertical pipes at the pump inlet, with the fluid flowing from bottom to top ； 　　6. The lift-type type has better sealing performance than the swing-type, but it creates greater fluid resistance; the horizontal type is suitable for use in horizontal pipelines, while the vertical type is suitable for use in vertical pipelines ； 　　7. The installation location of the swing check valve is not restricted; it can be installed on horizontal, vertical, or inclined pipelines. When installed on a vertical pipeline, the flow direction of the medium should be from bottom to top ； 　　8. Swing check valves are not suitable for use in small-diameter valves; they can operate at very high pressures, with a nominal pressure of up to 42 MPa. The nominal diameter can also be quite large, reaching over 2000 mm. Depending on the material of the housing and seals, it can be used with any working medium and in any operating temperature range. The media include water, steam, gases, corrosive substances, oils, pharmaceuticals, etc. The operating temperature range of the medium is between -196 and 800°C ； 　　9. Swing check valves are suitable for low-pressure, large-diameter applications, and their installation locations are limited ； 　　10. The installation location of the butterfly check valve is not restricted; it can be installed on horizontal pipelines as well as on vertical or inclined pipelines ； 　　11. Diaphragm check valves are suitable for pipelines where water hammer is likely to occur; the diaphragm helps to eliminate the water hammer that results from backflow of the fluid. They are generally used in low-pressure, normal-temperature pipelines, especially in water supply pipelines. The operating temperature of the fluid typically ranges from -12 to 120°C, and the operating pressure