1. Manual Unloader: When the manual unloader is open it vents to dome faster than it can be resupplied by the system pressure, causing the main valve to open.

2. Remote Unloader: The remote unloader, an electrically or pnuematically operated three-way valve which, when opened, vents the dome pressure faster than it can be supplied by the pilot source. This reduces teh dome pressure and opens the main valve.

3. Remote Valve Lift Indicator: A differential pressure switch is mounted between the pressure sensing line and the dome. Valve open condition is indicated when the dome pressure is lower than the system pressure.

4. Remote Pressure Sensing: The pilot senses the pressure directly from the protected vessel.

5. Lift Lever on Pilot: For compressed air service and vapor application.

6. Differential Sensing Filter System (DFS): Senses when the primary filter has become clogged and automatically switches the secondary filter, while giving a visual indication of a clogged filter.

7. Pilot Vent Connected to the Main Valve Outlet

8. Metal to Metal Seat (Main Valve): For use in very high pressure or temperature applications.

9. Switched Dual Pilots: Dual pilots allow for continuous service when maintenance is required on one pilot without compromising safety, system or production. The gauged 4-way valves insure the "out-of-service" pilot is depressurezed and can be safely maintained.

10. Dual Outlets: 4", 6" and 8"