Vacuum relief valves are set within systems that have significant enough pressure behind the fluid or gas inside them that it is possible the pressure in the system could decrease and reach a point that the piping system is not able to withstand. When the pressure inside a piping system decreases substantially, a vacuum is created because of the movement of the material inside the pipes. These vacuum forces can be extremely powerful, and the vacuum relief valve is used as the only means of relieving the piping system from the stress of the force created by the vacuum.
The vacuum relief valve is designed to open when the pressure inside the pipes drops to a point that may become hazardous to the system or any of the system components. Whenever the pressure is at a low enough point that causes instability in the system, the vacuum relief valve can be opened to release the vacuum. When the valve opens, the design of the operation of that particular valve determines the amount of material allowed into the piping system.
Vacuum relief valves can allow many different types of materials into systems, including fluid, gas, inert gas, or air. In these systems, the relief valve opens to let in enough material to compensate for the drop in pressure within the system. The amount of force needed to open the valve is dependent on the valve and the way it’s installed. The operator may also determine the amount of pressure that may be created inside the piping system before the vacuum relief valve opens.
In most applications, the vacuum relief valve is manufactured out of durable materials. Valves are commonly made from brass fittings and rubber gaskets. In general, however, the materials typically used depends on the materials the piping system in which they are installed are made out of.
This means that the valves typically match the pipes. For instance, if the piping system is constructed out of PVC plastics, the material that the relief valve will be made out of will be PVC threads and plastic components with rubber seals throughout. The matching material compositions typically allows for the proper sealing of the opening as the valve is applied to the system.