How does a safety valve work

The operating principle is demonstrated using the example of a proportional relief valve with a spring-loaded set point, installed in a water-filled system.

The principle of operation of the relief valve is based on the opposing forces on the valve: the force of the water trying to open the valve and the force of the spring trying to keep the valve closed.

The relief valve remains closed until the water pressure on the valve exceeds the force of the spring holding it closed. It should be noted that the opening pressure exceeds the relief valve's set pressure by approximately 3%.

After the valve lifts, further pressure rise will lead to a proportional increase in the valve lift and the volume of water being discharged. The relief valve fully opens when the pressure exceeds the set pressure by approximately 13%.

After the excess water has been discharged, the pressure at the relief valve installation point will start to decrease, and as soon as the spring force overcomes the static and dynamic pressure of the flowing water, the valve will close. The relief valve fully closes when the pressure at its installation point decreases to a value that is 20% less than the set pressure. This is due to the additional opposition of the dynamic pressure of the flowing water.

For more information on the set pressure, opening pressure, full opening, and closing of the relief valve, please refer to the Technical Specifications section.