What are the selection criteria for check valves?

Check valve selection standard vertebrae.

1, in order to prevent the media backflow, check valves should be installed on equipment, devices, and pipelines.

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

3, generally in the nominal diameter of 50mm horizontal pipeline should be selected horizontal lift check valve.

4, a straight-through lift check valve can only be installed in the horizontal pipeline.

5, for the pump inlet pipeline, it is appropriate to use the bottom valve, the bottom valve is generally installed only in the vertical pipeline of the pump inlet, and the media flow from the bottom up.

6, lift type than the rotary type sealing, fluid resistance, horizontal should be installed in the horizontal pipeline, vertically installed in the vertical pipeline.

7, swing check valve installation location is not restricted, it can be installed in the horizontal, vertical, or inclined pipeline, such as installed in the vertical pipeline, the media flow direction from the bottom up.

8, swing check valve should not be made into a small diameter valve, can be made into a very high working pressure, nominal pressure can reach 42MPa, and the nominal diameter can also be very large, the maximum can reach more than 2000mm. According to the shell and seal materials can be applied to any working medium and any working temperature range. The medium is water, steam, gas, corrosive medium, oil, medicine, etc. Medium working temperature range between -196--800℃.

9, swing check valve for occasions is a low-pressure large diameter, and installation occasions are restricted.

10, butterfly check valve installation position is not restricted, can be installed in the horizontal pipeline, can also be installed in the vertical or inclined pipeline.

11, the diaphragm check valve is suitable for easy to produce water strikes on the pipeline, the diaphragm can well eliminate the water strikes generated by the media backflow, it is generally used in low-pressure room temperature pipeline, especially suitable for water pipelines, the general medium working temperature between -12 - 120 ℃, working pressure <1.6MPa, but the diaphragm check valve can be larger caliber, DN can reach a maximum of 2000mm or more.

12, the spherical check valve is suitable for low and medium-pressure pipelines and can be made into a large diameter.

13, the shell material of the spherical check valve can be made of stainless steel, and the hollow sphere of the seal can be wrapped with PTFE engineering plastic, so in general corrosive media on the pipeline can also be applied, and the working temperature between -101 - 150 ℃, the nominal pressure ≤ 4.0MPa, the nominal through the range between DN200 - DN1200.

14, for incompressible fluids with check valve selection, the first step is to assess the required closing speed, and the second step is to select the type of check valve that may meet the required closing speed.

15, for compressible fluids with check valve selection, can be based on the incompressible fluids with check valve similar method to choose, if the media flow range is very large, then the check valve for compressible fluids can be used a reduction device, if the media flow continuously and uninterrupted rapid stop and start, such as the outlet of the compressor, then use the lift check valve.

16, check valve should determine the corresponding size, and the valve supplier must provide information data on the selected size so that the size of the valve can be found at a given flow rate when the valve is fully open.

17, for high and medium pressure check valves below DN50mm, it is appropriate to use vertical lift check valves and straight lift check valves.

18, for DN50mm or less low-pressure check valve, should use a butterfly check valve, vertical lift check valve, and diaphragm check valve.

19, for DN greater than 50 mm, less than 600 mm of high-pressure check valve, it is appropriate to use the swing check valve.

20, for DN greater than 200mm, less than 1200mm of the low and medium pressure check valve, should be used for the non-abrasive ball check valve.

21, for DN greater than 50mm, less than 2000mm low-pressure check valve, it is appropriate to use butterfly check valve and diaphragm check valve.

22, for the requirements of the closure of the water shock impact, is relatively small or no water shock pipeline, it is appropriate to use a slow-closing swing check valve and slow-closing butterfly check valve.

The process of check valve：

(1) the quality control of the main blank all parts of the valve are forgings, forging in strict accordance with the forging process procedures and process cards, strict control of the beginning forging temperature, final forging temperature, the degree of deformation and deformation speed, cooling according to the cooling method specified in the process procedures. Chemical composition analysis, mechanical property test, intergranular corrosion test, and metallographic analysis are carried out on the forged products, and the analysis, test, and determination are in accordance with the corresponding standards.

The quality of forgings is ensured by ultrasonic inspection and liquid penetration inspection. 100% ultrasonic flaw detection and evaluation of forgings are carried out according to the requirements of RCC-M, and liquid penetration inspection and evaluation of all surfaces of forgings are carried out.

(2) welding in order to improve the quality of overlay welding, the valve, and seat sealing surface overlay welding using the plasma argon arc welding process. At the same time, in order to ensure the quality of welding, the welding process used in the production of the process re-evaluated.

(3) assembly test quality products not only need high-precision parts, more critical is how to assemble these high-precision parts into high-performance products. CNNC Su Valve has organized an experienced and skilled assembly and a commissioning team composed of a number of technicians and senior technicians, responsible for the assembly, commissioning and testing of the valve, the development of the parts cleaning process, assembly process, strict control in the assembly and commissioning, excellence, to ensure the success of the valve assembly, commissioning, and various performance tests, the indicators are in line with the requirements of the design task book.

(4) process inspection of the valve prepared a quality plan to ensure that the valve from raw materials, blank input, machining, welding, heat treatment, non-destructive testing, cleaning, assembly, factory testing, and various type tests are quality control, and the second research and design institute of nuclear industry approved and on-site witness.

Butterfly double-valve check valve is suitable for high-rise building water supply network, a certain chemically corrosive media network, installation space has limited pipeline network, also suitable for sewage pipeline network.

Lifting silent check valve is suitable for pipeline networks with high-quality requirements for water supply and drainage projects; pipeline networks with relatively high-pressure requirements (PN2.5Mpa); it can be installed at the outlet of the pump and is economical and practical water hammer check valve.

Lifting anechoic check valve is suitable for water supply and drainage systems, high-rise building pipeline network, can be installed at the outlet of the pump, with slight structural changes, can be used as a suction bottom valve, but not for sewage network.

Horizontal check valves are suitable for submersible, drainage and sewage pumps, especially for sewage and sludge systems.

The swing-open rubber check valve is suitable for use in domestic water pipeline networks; however, it is not applicable to sewage with many sediments

 

Swing open single valve check valve is suitable for water supply systems, petroleum, chemical, metallurgy, and other industrial sectors are most applicable to places with installation space restrictions.

 

How should the check valve be installed?

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