Flow Safe Safety Relief Valve Eliminates Leak in Low Pressure Conditions

The Client: Natural Gas Distribution Company in New York State

A natural gas distribution company located in New York needed a reliable pressure relief solution for their low-pressure piping system. With strict performance and safety requirements, the customer needed a valve that could operate at extremely low pressures while providing dependable overpressure protection.

The Challenge:

The customer required a Low Pressure Relief Valve to protect their piping system at 18” W.C. The Flow Safe F70PR LP was selected for its large diaphragm to sense upstream pressure and its pilot operated relief design.

Flow Safe Valves can operate bubble tight up to 95% of set pressure (17.1” W.C.)  and vent the piping system at 18”. However, the customer’s piping system was operating at extremely low pressures (7-10” W.C.), which led to seat leakage issues. 

The Solution:

To ensure optimal performance, R.M. Headlee, the customer, and Flow Safe Valves collaborated on-site to conduct testing, which determined that the operating pressure was too low for the Back Pressure Check Valve to function properly. There was insufficient pressure to overcome the check valve piston and send gas to the pilot, resulting in no pressure loading the dome (the top side of the piston). As a result, the gas was lifting the piston directly, causing the leak during testing.

By removing the check valve and retesting, the Flow Safe F70PR LP – 3-150# RF x 4-150# RF performed flawlessly, maintaining tight operation and venting properly. The modification allowed the valve to function correctly under both low pressure and normal operating conditions.