Why Is The Safety Valve Setting The Set-pressure Similar To The Broken Pressure?

This is because the safety valve is responsible for reducing the pressure in the system as quickly as possible to prevent damage caused by excessive pressure as quickly as possible.

valve face design

By closing the force against the force of the spring will have a force acting on the red area, but when it is opened The action force will increase with the area red and orange combined.

As a result, the pressure required to open (set pressure) will be greater than the pressure required for the valve to close ( reseating pressure).

For example, in our system By referring to the opening and closing from the graph below.

Full lift safety valve                                  Standard safety valve

For Full lift safety valve, if we set the set pressure to 10 barg, the valve face will start to open at 10 barg (0%) and will continue to open until the valve face is 100% raised at 10.5 barg (+5%) pressure when venting. Push in the system until it's gone. valve face will fall and sealed at a pressure position of 9 barg (-10%).

Flowork recommends setting the set pressure 15-20% higher than the working pressure to avoid reseating pressure (by the customer Must check with the maximum pressure value or MAWP value) Set pressure must always be less than or equal to MAWP.

Installation example

If it is a safety valve that works with steam Don't forget to install The sewer is designed in the figure. Also do not install the isolation valve before the safety valve.