1 Selection of
Gate Valve Generally,
Gate valve shall be preferred. In addition to steam, oil and other media, gate valves are also suitable for media containing granular solids and high viscosity, and for valves in vent and low vacuum systems. For the medium with solid particles, the gate valve body shall be equipped with one or two purging holes. For low temperature medium, low temperature special gate valve shall be selected.
2 Description of selection of stop valve
The stop valve is applicable to the pipeline with less strict requirements on fluid resistance, that is, the pipeline or device with little consideration on pressure loss and high temperature and high pressure medium, and is applicable to the steam and other medium pipeline with DN ＜ 200mm; Stop valves can be selected for small valves, such as needle valve, instrument valve, sampling valve, pressure gauge valve, etc; The stop valve has flow regulation or pressure regulation, but it does not require high regulation accuracy, and the pipe diameter is relatively small, so the stop valve or throttle valve should be selected; For highly toxic media, the stop valve sealed with bellows 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 should it be used as a vent valve and a valve for low vacuum system.
3 Description of
Ball Valve selection
Ball valve is applicable to 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 powder and granular media according to the requirements of sealing materials; Full-channel ball valve is not suitable for flow regulation, but it is suitable for occasions requiring quick opening and closing, so as to realize emergency cut-off in case of accident; Generally, ball valves are recommended for pipelines with strict sealing performance, wear, shrinking channel, rapid opening and closing action, high pressure cut-off (large pressure difference), low noise, gasification, small operating torque and small fluid resistance; Ball valve is applicable to light structure, low pressure cut-off and corrosive medium; Ball valve is also the most ideal valve for low temperature and cryogenic medium. For the pipeline system and device of low temperature medium, the low temperature ball valve with valve cover should be selected; When floating ball valve is selected, its seat material shall bear the load of ball and working medium. Large-diameter ball valve requires large force during operation. Ball valve with DN ≥ 200mm shall adopt worm gear transmission; Fixed ball valve is suitable for large diameter and high pressure occasions; In addition, the ball valve used for the pipeline of highly toxic materials and combustible media in the process shall have a fireproof and anti-static structure.
4 Description of throttle valve selection
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, and is not suitable as a block valve.
5 Description of plug valve selection
The plug valve is applicable to the situation that requires quick opening and closing. It is generally not applicable to steam and medium with high temperature. It is also applicable to medium with low temperature and high viscosity. It is also applicable to medium with suspended particles.
6 Description of
Butterfly Valve selection
The butterfly valve is applicable to situations with large diameter (such as DN>600mm), short structural length requirements, and the need for flow regulation and fast opening and closing requirements. It is generally used for water, oil, compressed air and other media with temperature ≤ 80 ℃ and pressure ≤ 1.0MPa; Because the pressure loss of butterfly valve is relatively large compared with that of gate valve and ball valve, butterfly valve is applicable to the pipeline system with low pressure loss requirements.
7 Description of
Check Valve selection
The check valve is generally suitable for cleaning media, and should not be used for media with solid particles and high viscosity.
When DN ≤ 40mm, lift check valve should be used (only allowed to be installed on horizontal pipeline);
When DN=50~400mm, the swing lift check valve should be used (it can be installed on both horizontal and vertical pipes. If it is installed on vertical pipes, the medium flow direction should be from bottom to top);
When DN ≥ 450mm, buffer-type check valve should be used;
Wafer check valve can also be selected when DN=100~400mm;
The swing check valve can be made into a high working pressure, PN can reach 42MPa, and can be applicable to any working medium and any working temperature range according to the different materials of the shell and seal. The medium is water, steam, gas, corrosive medium, oil, medicine, etc. The working temperature range of medium is - 196~800 ℃.
8 Description of diaphragm valve selection
Diaphragm valve is applicable to oil, water, acidic media and media containing suspended solids with working temperature less than 200 ℃ and pressure less than 1.0MPa, and is not applicable to organic solvent and strong oxidant media; The weir diaphragm valve should be selected for grinding granular media, and the weir diaphragm valve should be selected according to its flow characteristic table; The straight-through diaphragm valve should 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.
The application, operation frequency and service of valves are changing. The most important and critical equipment to control or eliminate even minor leakage is valves. It is important to learn how to select the valve correctly.
WUXI KVC-VALVE