Is it easy to change a control valve from air-open to air-close (or from air-close to air-open)?
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Is it easy to change a control valve from air-open to air-close (or from air-close to air-open)? How to do it?
It’s not easy to modify; cylinder-type butterfly valves are easy to modify, while single-seat ones are very difficult
There are some differences in manufacturing methods among products from different manufacturers; some are easy to modify while others are not. It is best to consult the manufacturer for specific details.
Well-known brands are easy to modify, as they take versatility into account when designing their products; low-quality brands are difficult to modify. Generally speaking, those with angular travel can be modified, while most of those with linear travel cannot.
Those with that function will work; if not, some components such as valve stems and actuators need to be replaced
Let’s go through them one by one: First: Angle seat valves are equipped with piston-type actuators that operate in a single-acting manner. It’s easier for ball valves, as they can rotate 360°; simply turning the actuator by 90 degrees suffices. Butterfly valves, however, cannot rotate such a large angle – especially triple-eccentric butterfly valves, which can only rotate 90°. Therefore, no modification is possible; an alternative actuator must be used. Double-acting actuators are easier to modify, so I guess there’s no need to explain further； The valve with a second linear stroke uses a diaphragm-type actuator that is single-acting; this cannot be changed – only the actuator can be replaced. For double-acting actuators, the same approach can be used as mentioned above. Of course, after modifying the mechanical parts, the valve positioner also needs to be altered, which goes without saying
It can be modified at the factory; the cost is estimated to be similar to that of buying a new one.
If it is a straight-through two-seat or single-seat valve, it is easy to modify.
Basically, it’s necessary to replace the film head; some companies allow for the exchange of film heads
It is generally not recommended to make changes; instead, a new nozzle is needed and the travel distance must be adjusted again, which is quite troublesome. If there are spare parts available, it’s better to use those instead