Introduction

Figure 1. H721 and H731 Series Flush Mounted Internal Relief Valve

The Types H721 and H731 relief valves are installed in tanks, both stationary and mobile, as a means of preventing excessive overpressure. These units are used primarily in trucks transporting LP-Gas (propane) or ammonia. The stainless steel construction increases resistance to rust and corrosion, and makes it easy to remove the valve from the tank for the required periodic testing.

The complete valve is secure inside the tank with only the nameplate extending above the coupling. A special installation wrench can be inserted into the valve socket to provide a means of attaching a standard wrench.

Features

• True Internal Design
• Standard Spring Settings
• Easy Maintenance
• Nitrile Disk

Start-To-Discharge Setting

• 250 psig (17,2 bar)
• 265 psig (18,3 bar)
• 275 psig (19,0 bar)

Temperature Capabilities
-20° to 150°F (-29° to 66°C)

Container Connection Sizes
See Table 2

Additional Technical Data
For more technical information contact your Fisher Distributor or refer to LP-31 Equipment Buyer’s Guide.

Figure 2. Dimensions