Overpressure Protector is designed to protect your gauge from pressures that exceed its rated capacity, preventing the loss of calibration, damage to internal components, and rupture of the sensing element. This protective device consists of a spring-loaded piston valve held open by the spring under normal pressure conditions. When the system pressure exceeds the set pressure, the force of the spring is overcome, and the valve closes. The valve will remain closed until the system pressure drops approximately 25% below the closing pressure, at which point the force of the spring will open the valve again.
To adjust the closing pressure of your overpressure protector, turn the adjusting screw on the side of the body either clockwise (inward) or counterclockwise (outward). Clockwise rotation will raise the closing pressure, while the counterclockwise rotation will lower it. The recommended range for setting the closing pressure is between 1.0 and 1.3 times the full-scale value. If needed, the closing pressure can be selected at a range lower than the full-scale value.
To correctly set the closing pressure of an overpressure protector, you need to attach a reference gauge and subject gauge to the protector. Both gauges must be connected to the same pressure source, with the reference gauge having a higher pressure rating than the subject gauge. Once the gauges are connected, check that they are both reading the same pressure level and adjust the pressure of the overpressure protector accordingly.
To ensure optimal performance, it is vital to determine the initial setting of the overpressure protector before use. The protector is not pre-set from the factory but is generally set in the middle of the closing pressure range. Once you have determined the closing pressure, you can adjust the setting as needed to ensure the proper functioning of the protector.
To set the full-scale value of your subject gauge, follow these steps:
Step 1: Slowly increase the pressure of the subject gauge to the full-scale value.
Step 2: If the overpressure protector does not stop the inlet pressure before reaching the full-scale value, turn the adjusting screw counterclockwise.
Step 3: Repeat this process until the closing pressure can be read accurately on the subject gauge.
You can now easily set the closing pressure of your overpressure protector with the following steps:
Step 1: Turn the adjusting screw clockwise by a small amount (1/4 to 1/2 turn) and gradually increase the pressure of the subject gauge until you reach the desired closing pressure.
Step 2: If the closing pressure of the subject gauge is set above the full-scale value, use the reference gauge to determine the correct pressure setting.
Step 3: Once the closing pressure is obtained, securely tighten the set screw to prevent movement of the adjusting screw.
Once the closing pressure has been set on the reference gauge, it can be tested to ensure that the overpressure protector is working correctly. For instance, in the pictures above, the subject gauge has been set to a closing pressure of 58 psi. The reference gauge (picture 3) can be pressurized to a higher value, such as 80 psi, to verify the closing pressure. As the pressure builds, you will notice that the overpressure protector will “shut off” or “block” the pressure from getting to the subject gauge when it reaches the predetermined closing pressure of 58 PSI.
Adjust the closing pressure of your overpressure protector with ease using this adjusting screw. Turning the screw clockwise increases the closing pressure while counterclockwise lowers it.
The set screw is an integral part of the pressure regulation system. It is tightened after the closing pressure has been set and designed to prevent the adjustment screw from shifting out of place and altering the pressure settings. Therefore, the set screw is an essential tool for ensuring the accuracy of your pressure settings.