Safety valves are widely used across the entire process industry. They are often the most important safety barriers in a process, as they protect system components against mechanical damage or bursting into the environment.

It is typical to set the response pressure between 5 to 10% above the operating Pressure ‘PS’.

There are two main types of safety valve which can be differentiated by their behaviour:

• Proportional Safety Valve - Relieves system fluid proportional to the pressure increase. The higher the upstream flow, the higher the relief exhaust.

• Full Stroke Safety Valve - Opens the relief orifice at a maximum ‘full stroke’ and relieves overpressure until it is below the maximum operating pressure (hysteresis) until it closes.

Furthermore, there are also Pilot operated safety valves, which combine behaviour of different types and enable larger flows.