Description of common valve selection

1.Model selection description of gate valve

In general, gate valves shall be preferred. In addition to steam, oil and other media, gate valves are also suitable for media containing granular solids and high viscosity, as well as valves for venting and low vacuum systems. For the medium with solid particles, the valve body of the gate valve shall be provided with one or two purge holes. For low-temperature medium, low-temperature special gate valve shall be selected.


2.Model selection description of stop valve

The stop valve is applicable to the pipeline that does not have strict requirements on fluid resistance, that is, the pipeline or device that does not consider the pressure loss and high-temperature and high-pressure media, and is applicable to the pipeline of steam and other media with DN ＜ 200mm; Small valves can be globe valves, such as needle valves, instrument valves, sampling valves, Pressure Gauge Valves, etc; The stop valve has flow regulation or pressure regulation, but the regulation accuracy is not high, and the pipeline diameter is relatively small, so it is better to select the stop valve or throttle valve; For highly toxic media, the bellows sealed stop valve should be selected; However, the stop valve should not be used for medium with high viscosity and medium containing particles that are easy to precipitate, nor for vent valve and valve of low vacuum system.

3.Description of ball valve model selection

The ball valve is suitable for medium with low temperature, high pressure and high viscosity. Most ball valves can be used in media with suspended solid particles, and can also be used in powdery and granular media according to the sealing material requirements; The full channel ball valve is not suitable for flow regulation, but it is suitable for occasions requiring rapid opening and closing, so as to facilitate emergency cut-off in case of accident; Generally, ball valve is recommended for pipelines with strict sealing performance, wear, necking channel, rapid opening and closing action, high-pressure cut-off (large differential pressure), low noise, gasification, small operating torque and small fluid resistance.

The ball valve is suitable for light structure, low-pressure stop and corrosive medium; The ball valve is also the most ideal valve for low-temperature and cryogenic media. The low-temperature ball valve with valve cover should be selected for the pipeline system and device of low-temperature media; When the floating ball valve is selected, the valve seat material shall bear the load of the ball and the working medium. The large-diameter ball valve requires large force during operation, dn≥ The 200mm ball valve shall be worm driven; The fixed ball valve is applicable to the occasions with large diameter and high pressure; In addition, the ball valve used for the pipeline of highly toxic materials and combustible media shall have fire-proof and anti-static structure.

4. Model selection description of throttle valve

The throttle valve is applicable to the occasions with low medium temperature and high pressure, and is applicable to the parts where the flow and pressure need to be adjusted. It is not applicable to the medium with high viscosity and containing solid particles. It should not be used as a block valve.

5.Plug valve model selection instructions

The plug valve is applicable to the occasions requiring quick opening and closing. Generally, it is not applicable to steam and medium with higher temperature. It is also applicable to medium with lower temperature and high viscosity and medium with suspended particles.

6.Butterfly valve type selection description

The butterfly valve is applicable to the occasions with large diameter (such as DN ＞ 600mm) and short structural length requirements, as well as the occasions requiring flow regulation and quick opening and closing. It is generally used for temperature ≤ 80 ℃, pressure ≤ 1.0MPa water, oil, compressed air and other media; As the pressure loss of butterfly valve is relatively large compared with that of gate valve and ball valve, butterfly valve is suitable for pipeline systems with lax pressure loss requirements.

7. Model selection description of check valve

Check valves are generally applicable to clean media, and should not be used for media containing solid particles and large viscosity. When ≤ 40mm, lift check valve should be used (only allowed to be installed on horizontal pipeline); When DN ＝ 50 ～ 400mm, swing lift check valve should be used (it can be installed on both horizontal and vertical pipelines. If installed on vertical pipelines, the medium flow direction should be from bottom to top); When DN ≥ 450mm, buffer check valve should be used; When DN ＝ 100 ～ 400mm, the wafer check valve can also be selected; The swing check valve can be made into a very high working pressure, and the PN can reach 42MPa. It can be applied to any working medium and any working temperature range according to the material of the shell and seal. The medium is water, steam, gas, corrosive medium, oil, medicine, etc. The working temperature range of the medium is -196 ~ 800 ℃.

8.Model selection description of diaphragm valve

The diaphragm valve is applicable to oil products, water, acidic media and media containing suspended solids with operating temperature less than 200 ℃ and pressure less than 1.0MPa, and is not applicable to organic solvents and strong oxidant media; Weir type diaphragm valve should be selected for grinding granular medium, and its flow characteristic table should be referred to when selecting weir type diaphragm valve; Straight through diaphragm valve shall be selected for viscous fluid, cement slurry and sedimentary medium; Except for specific requirements, diaphragm valves should not be used on vacuum pipelines and vacuum equipment.