Bench Set Control Valve
Actuator bench set response graph the diagram above is for a direct acting atc fo air to close fail open control valve with a signal of 3psig signifying a fully open valve and 15psig a fully closed valve.
Bench set control valve. Given by below formula. Bench set is an important parameter to the control valve because it establishes the seating load of the valve plug against the seat when the valve is fully closed. For example if we have an air to open actuator with a bench set spec of 7 15 psi.
As already explained in control valve actuator bench set and valve stroking the bench set of a control valve is the pressure range required to stroke the valve from a fully closed to a fully open position. Bench set consist of considering all the factors and forces selecting a spring with the correct spring rate and setting an initial compression on the spring. The actuator diaphragm will bind travel at the upper end and the valve plug will bind travel at the.
The bench set pressure range is used to adjust the initial compression of an actuator spring with the valve assembly on the bench the correct initial compression is important for the. The result is a control valve assembly that responds differently when tested on the bench than when it is installed in the process where all active forces are in effect. If the stem connector is set with the actuator and valve stems spaced too far apart which means the total stem length is too long.
In this article i will cover the bench ser range of the control valve actuator. Hooke s law directly gives a relation between the applied force and the elasticity of the spring. Proper seating pressure is critical for tight shut off which carries safety implications in some process services.
The pneumatic actuator operates on the principle of the hooke s laws to applied air pressure to valve stem position. Bench set is a very important parameter for a control valve because it establishes the seating force seat load of the plug against the seat when the valve is fully closed. Consult the manufacturer s instructions when adjusting.
The graph below shows the bench set response of an actuator. Screw the stem locknuts all the way onto the valve stem. Bench set is a very important parameter for a control valve because it establishes the seating force seat load of the plug against the seat when the valve is fully closed.
Proper seating pressure is critical for tight shut off which carries safety implications in some process services. During bench set spring adjustments.
