Discussion on the air supply pressure for valve instruments
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This post was last edited by lflsedin on 2018-1-13 09:18. As the title suggests, due to the effect of pressure drop, the pressure of the air supply used to control these valves will certainly vary in actual operation. Is it necessary to calculate the air supply pressure for each valve when designing them? How significant is it for the design of the actuator?
It is of great significance for the selection of actuators. The parameters relevant to the selection of actuators include not only the pressure difference before and after the process medium but also the pressure and flow rate of the instrument air supply. For example, if the gas source pressure is low, the membrane element needs to be larger; if the pipes have a small diameter and thus a low flow rate, it is necessary to determine whether a booster is required – all of these factors need to be taken into consideration.
"Control valve steam source”? A steam digger with three dots? ! Oh my, is it high-pressure steam that is used to drive the actuator? So mighty! It must be a huge valve; it’s probably several stories tall, and several cranes would be needed to lift it, right, OP? . .
There is no need to consider the air supply pressure for valves, as the outlet pressure of compressors is generally between 0.7–0.8 Mpa; no matter what the resistance may be, it cannot drop to 0.3 Mpa. Ordinary pneumatic diaphragm control valves can be operated with just 0.3 Mpa of pressure, and cylinder valves also require only 0.4–0.5 Mpa to function – unless it’s some special type of valve. For actuators, however, their thrust needs to be taken into consideration.