Double-acting cut-off valve
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What is the advantage of a double-acting shut-off valve over a single-acting one? In an emergency situation, when the pressure in the air tank is lost, a single-acting valve cannot be closed.
Double-acting valves are generally cheaper than single-acting ones in terms of spring reactivation (for large-diameter, high-torque applications, the cylinder on the side of the valve in single-acting cylinders is very long, which affects piping). Double-acting valves use air storage tanks to achieve the fault position; in the event of a failure and the pressure in the storage tank is lost, unless fault position functionality was not specified during purchase, the valve should remain in its original position and not move when there is no supply of instrument air.
It seems that when the cylinder diameter reaches a certain size, single-acting cylinders are no longer suitable. Where air inlets and outlets are needed, these are achieved through air storage tanks and various control devices.
Single-acting and double-acting – neither is better or worse; it’s just that the application requirements differ. For process switching applications where there is no requirement regarding the valve position in case of a fault, double-acting valves are used; whereas if it is necessary for the valve to be in an open or closed state in case of a fault, single-acting ESD valves and BDV valves must be used, as these are definitely single-acting
In the case of a double-acting shut-off valve, when the solenoid is powered, a single-acting shut-off valve relies on a spring for reset; whereas double-acting valves require a certain pressure from the air supply. Due to potential leaks in the system, double-acting valves may fail to close if the air pressure is insufficient.
We’re not using valves of the process switching type.
Based on the process requirements, it should remain in place in case of a fault; if there’s no need to switch it on or off when faulty, then go with a double-acting type
Two-way operation is generally used in situations where an emergency state is not required, right?
Sorry, what kind of valve is BDV? SDV, right? Shut-off valve???
blowdown, vent valve
If the valve is required to reset automatically in the event of a gas supply failure, then a single-acting cylinder is needed. Some customers consider costs; for example, in the case of ball valves with larger diameters, such as DN250, there is a significant price difference between single-acting and double-acting cylinders. In such situations, if it is necessary for the valve to be able to reset, a double-acting cylinder can also be used, along with an air reservoir. There is no such thing as one type of cylinder being better than another; in essence, a single-acting cylinder simply has an additional set of springs at both ends compared to a double-acting cylinder. The choice of cylinder depends on the actual production conditions on site – there is no question of which is better or worse, only whether it is suitable or not.