Balanced Bellow Safety valve

Balanced Bellows  Safety Valve is often used for the pipelines with toxic or corrosive medium.It's often supplied with closed bonnet with or without lever. We Goole can also offer Jacketed Bellow Type Balanced Safety Valve.

Balanced Bellows Safety valve should be used in the following condition:

1. When a double tightness barrier is required by the process fluid in the secondary pressure zone of the safety relief valve.

2. When the valve is subjected to a back pressure of between 10% and 50% of the set pressure.

3. When a conventional safety relief valve discharges against a back pressure, the opening pressure is the set pressure with atmospheric back pressure augmented by the actual superimposed back pressure just before the valve opens. 

If the back pressure is variable, then the opening pressure of a conventional valve will also be variable.

To solve this problem, it is highly recommended to use a balanced bellows safety relief valve. The effective area of the bellows is substantially the same as the seating area of the disc on the nozzle and the bellows is vented to atmosphere through a hole drilled into the bonnet wall. The opening pressure of the safety relief valve is then independent of the back pressure.