The overpressure protector for pressure measuring instruments is a piston valve. Through a helical spring, the outlet position is maintained until the pressure acting on the piston overcomes the back pressure of the spring, thus closing the valve.
Once the pressure drops below the closing pressure by approx. 25 %, the valve opens again and the piston returns to its rest position under the action of the spring force.
The closing pressure is set to half of the span of the respective setting range.
Set values for factory mounting
When mounted onto a pressure measuring instrument by WlKA, the overpressure protector is set to 1.1 times the full scale value of the pressure measuring instrument.
Setting the closing pressure
If the adjustment screw is turned clockwise, the spring force of the helical spring increases and, with it, the closing pressure. By turning the adjustment screw anti-clockwise, the closing pressure is reached at lower pressure values.
For the setting of the optimal closing pressure, the temperature at the measuring location must be taken into account.
This overpressure protector is not suitable for use as a controller or for control and regulation purposes.