A safety valve is used to automatically release material in order to change a system’s temperature or internal pressure. These mechanisms are very common on devices that use heated liquid, particularly water, to create mechanical energy. Older safety valves were often manually-operated, but modern valves are generally tied into a diagnostic system. This system constantly monitors the connected device for changes that could result in a dangerous situation. If it detects a problem, the safety valve will trigger automatically to help prevent an explosion or rupture.
The systems using safety valves usually have portions with extreme temperature, pressure or circulating liquid. Devices such as steam boilers, hot water heaters and refrigeration systems all use safety valves as a method of keeping them from exploding. When the pressure rises above a prescribed amount or temperature differences begin to endanger the system’s physical structure, the safety valve will trigger to equalize the system.
In most cases, a safety valve is placed in the bottleneck of a system or in a dead-end pipe off of important or troublesome locations. When placed in an active system, the valve remains open all the time. When triggered, it will close and prevent material from passing further into the system. When the valve is off to the side, it will remain closed all the time. If the connected area registers a problem, the valve will open and expel material from the device.
Modern valves are often connected to internal sensors that constantly monitor the various areas of the system. These sensors are looking for problems that might endanger the machine or the people around it. If the pressure is too high, the systems could explode, pelting workers with super-heated liquid and shrapnel. If a portion of the device is very hot or cold and a material of the opposite temperature attempts to access that area, the temperature change could cause metal to crack.
In addition to these types of valves, many devices still use an eject plug as a safety valve. While these plugs aren’t technically valves, they perform the same function as a valve and are often the main valve’s backup device. An eject plug in a solid plug that fits tightly into a hole. Should the pressure in the system get very high, and the safety valve doesn’t trigger, the plug will be forced from its hole and the pressure will equalize. Like a safety valve, eject plugs often go unused for long periods of time and need to be checked occasionally to ensure that they are still in good shape.