with the same function can be divided into various types, and can have different characteristics. Besides meeting the functional requirements, other factors such as the adaptability of the valves' media, the valves' flow characteristics, and the valves' sealing features should also be taken into account when valves
Here are some examples of engineering shut-off valves.
When the media are sensitive to the pressure drop, valves
with small flow resistance and good flow performance should be selected. For example, for the devices in which there have many low-pressure medium pipes, negative pressure pipes, gravity flow pipes, etc., low pressure drop valves should be used, and check valves
with the spring return should not be picked up.
For media which are sensitive to the flow state, valves
with small resistance and good flow performance should be chosen. For example, for the medium condition under which the gasification of the media may occur with pressure fluctuations, the turbulence of the media should be minimized when they flow through the valve
to avoid the adverse effects of the gasification.
For the high pressure medium conditions, valves
with small resistance and good flow performance should be picked up because the flow rate of the media is high under high pressure conditions, leading to great pressure drop and increasing the operation costs of the production facilities.
For the medium conditions with high frequency fluctuations, valves
with small resistance and good flow performance should be selected, which not only can reduce the resistance of the fluids as well as the operation costs of the devices, but also can weaken the vibration of pipes by reducing the exciting force caused by the pressure fluctuations.
For the medium conditions with special requirements, it goes without saying that the selected valves
should meet the special requirements. For example, for long-distance pipelines with the pigging requirement, valves are supposed to meet the pigging requirement.
For the media with great viscosity or the pipelines transporting powder, the ultimately selected valves
should not have any dead zones where media can stay for a long time. For example, gate valves with the valve seat groove should not be used because the media will block the valve discs so as to make the valves can not be properly used.
For the hazardous media such as the media stipulated by the definition of GB/T5044, valves
with good sealing performance such as bellow valves and diaphragm valves must be chosen.
Affected by the environmental temperature, for the medium conditions under which falsification will easily occur, valves
which will form closed cavities or valves with the automatic pressure relief system are not recommended to be used.