Regarding valve selection issues

Based on the operator’s strength, pneumatic systems are used for frequent switching.

Gate valves can shut off flow, while butterfly valves can both shut off flow and regulate it

Same question: in what situations is electric control used, and in what situations is pneumatic control used? Seeking expert advice to resolve this confusion

In my opinion, electric actuators should be used less for valves, while pneumatic actuators are more suitable; pneumatic actuators are preferred when high explosion-proof requirements are involved.

Principles for selecting gate valves/butterfly valves: Gate valves are used for forced shut-off; they present little flow resistance when fully open, but are large in size and costly； Butterfly valves are generally used for regulation, but can also be used for shut-off. The smaller the diameter, the greater the flow resistance. Nowadays, it is not a problem to achieve virtually zero leakage with so many different types of butterfly valves available. Small size, low cost. It should be considered comprehensively. Selection basis for electric/pneumatic actuators: Electric and pneumatic types are generally determined based on the requirements of the owner or the design institute ； Electric: energy-consuming, easy to control; the preferred choice for applications requiring high torque (relatively low cost). Pneumatic systems are energy-efficient, come with many control accessories, and have a high cost; they are the preferred choice for applications that require rapid shutdown.

Premise: Electric valves are more expensive than pneumatic valves. Then there are various situations: for example, if you require quick shutdown, electric systems won’t work; pneumatic systems are necessary, and it might even be necessary to use a weight as well. Another scenario is when there are many compressed air devices on site – in that case, we use cheaper pneumatic valves, since those devices are already available. Well, to give an example, when should you use electric power? For instance, when you need precise adjustment?

Pneumatic ball valves are generally chosen for storage and transportation, as they offer good sealing performance and reliable pneumatic safety features! But generally, ball valves are not chosen for sizes above DN300 (400)

For storage and transportation, electric actuators are generally the preferred choice for automatic valves; gate valves and flat gate valves are commonly used in process pipelines, while ball valves are employed in some chemical applications. Butterfly valves are commonly used in utility systems. In terms of capacity, electric valves are generally used for those over 150, while manual valves are more common for those under 150. Of course, frequency of operation also plays a role; automatic valves are preferred for valves that need to be opened and closed frequently. Storage and transportation devices generally require a large amount of space; pneumatic ones are less so, and unless there are special requirements, they are rarely found in storage facilities. On the one hand, there is a torque limit for large-diameter valves; on the other hand, costs also pose a constraint