1. Selection of gate valve
In general, gate valves should be preferred. Gate valves are not only suitable for steam, oil and other media, but also for medium containing granular solids and large viscosity, and suitable for vent and low vacuum system valves. For media with solid particles, the gate valve body shall have one or two purging holes. For low temperature medium, special low temperature gate valve should be selected.
2. Description of globe valve selection
Globe valve is suitable for the fluid resistance requirements of the pipeline, that is, the pressure loss is not considered, and high temperature, high pressure medium pipeline or device, suitable for DN < 200mm steam and other media pipeline; Small valves can choose globe valve, such as needle valve, instrument valve, sampling valve, pressure gauge valve, etc. Globe valve has flow regulation or pressure regulation, but the adjustment accuracy is not high, and the diameter of the pipeline is relatively small, should choose globe valve or throttle valve; For highly toxic medium, it is appropriate to choose bellows sealed globe valve; However, the globe valve should not be used for medium with large viscosity and medium containing particles easy to precipitate, nor should it be used for vent valve and low vacuum system valve.
3, Ball valve selection instructions
Ball valve is suitable for low temperature, high pressure, viscosity of the medium. Most ball valves can be used with suspended solid particles in the medium, according to the sealing material requirements can also be used for powder and granular media; Full-channel ball valve is not suitable for flow regulation, but it is suitable for the occasions requiring fast opening and closing, which is convenient for the realization of emergency cut-off of accidents; Usually in strict sealing performance, wear, shrinkage channel, opening and closing action quickly, high pressure cut-off (pressure difference), low noise, gasification phenomenon, small operating torque, small fluid resistance in the pipeline, recommended the use of ball valve; Ball valve is suitable for light structure, low pressure cut-off, corrosive media; Ball valve or low temperature, cryogenic medium is the most ideal valve, low temperature medium pipeline system and device, should be used with the valve cover low temperature ball valve; Selection of floating ball valve valve seat material should undertake the ball and working medium load, large diameter ball valve in operation requires greater force, DN≥200mm ball valve should be selected worm gear transmission form; Fixed ball valve is suitable for larger diameter and higher pressure occasions; In addition, the ball valve used for the process of highly toxic materials, combustible medium pipeline, should have a fireproof, anti-static structure.
4, Throttle valve selection instructions
Throttle valve is suitable for medium temperature is low, high pressure occasions, suitable for the need to adjust the flow and pressure parts, is not suitable for viscosity and contains solid particles of the medium, not as a partition valve.
5, Plug valve selection instructions
Plug valve is suitable for fast opening and closing occasions, generally not suitable for steam and high temperature medium, for low temperature, high viscosity medium, also suitable for medium with suspended particles.
6, Butterfly valve selection instructions
Butterfly valve is suitable for large diameter (such as DN>600mm) and short structure length requirements, as well as the need for flow regulation and fast opening and closing requirements of the occasion, generally used for temperature ≤80℃, pressure ≤1.0MPa water, oil and compressed air and other media; Compared with gate valves and ball valves, butterfly valves are suitable for pipe systems with lax pressure loss requirements.
7, Check valve selection instructions
Check valves are generally suitable for clean media, not for media containing solid particles and viscosity. When DN≤40mm, use lifting check valves (only allowed to be installed on horizontal pipelines); When DN = 50 ~ 400mm, it is appropriate to use swing lifting check valve (in horizontal and vertical pipeline can be installed, such as installed in vertical pipeline, medium flow from bottom to top); When DN≥450mm, the buffer type check valve should be used; When DN = 100 ~ 400mm can also choose the wafer check valve; Swing check valve can be made of high working pressure, PN up to 42MPa, according to the shell and seal material can be applied to any medium and any operating temperature range. Medium is water, steam, gas, corrosive medium, oil, medicine, etc. The working temperature of the medium is between -196 ℃ and 800℃.
8, Diaphragm valve selection instructions
Diaphragm valve is suitable for working temperature is less than 200℃, pressure is less than 1.0MPa oil, water, acidic medium and suspended medium, is not suitable for organic solvents and strong oxidant medium; Abrasive granular medium should choose weir diaphragm valve, weir diaphragm valve should refer to its flow characteristics table; Viscous fluid, cement slurry and precipitation medium should choose straight through diaphragm valve; Diaphragm valves should not be used on vacuum lines and vacuum equipment unless specified.
Valves vary in application, frequency of operation and service. To control or eliminate even minor leaks, valves are the most important and critical equipment. Learning to choose the right valve is crucial.
Post time: Nov-19-2021