Pressure Relief Valve - 50M-5 | Cla-Val

Cla-Val 50M-5 Remote Sensing Pressure Relief Valve

The Cla-Val 50M-5 is a pressure relief valve with remote sensing capability, designed for marine fuel oil transfer systems on surface vessels. Operation is based on pilot control, with reference pressure taken from a remote point in the line, ensuring relief is triggered by the actual pressure at the critical section of the network.

Technical Classification

• Type: Remote Sensing Pressure Relief Valve
• Service: Marine fuel oil transfer system
• Body: Globe pattern
• Available sizes: 1 1/2" to 8"
• Angle pattern: 8" angle pattern
• Flange specification: MIL-F20042 Class 150 / Class 250
• Union-style option: MIL-F1183

Operation in Fuel Oil Transfer

The 50M-5 opens when the sensed pressure exceeds the pilot setpoint, diverting flow to return, bypass, or other designated system points. Remote pressure sensing is critical where valve body pressure does not represent the pressure to be protected, due to line losses, elevation differences, or pump location.

Comparison with Local Relief Valves

Local relief valves respond to pressure at the installation point. The 50M-5 uses a sensing line for control from a different network location. This is relevant in fuel oil transfer skids, where discharge, manifold, or downstream equipment pressures may vary significantly.

Selection Considerations

For technical selection, confirm the following:

• Set pressure and remote sensing location
• Maximum relief flow rate
• Fuel oil viscosity and temperature
• Back pressure in return line
• Flange class or union connection
• Access to pilot, strainer, and sensing line

Maintenance

Inspection should include cleanliness of sensing line, pilot strainer, diaphragm, seat, set pressure, and tightness in closed position. For fuel oil service, check for deposits, paraffin, or blockages in small control passages.