These valves are pneumatically controlled fuel shutoff valves. They are designed to open and close automatically or semi-automatically. The pneumatic control pressure can be air, oil or gas. A manual lever aids in opening the valve when control pressure is insufficient. A gas escape vent, when properly vented and maintained, releases trapped gas from the valve after shutoff.

Basic operation is:
Automatic: As the control pressure/vacuum increase the valve will open. When the control pressure/vacuum decreases, the valve will close.
Semi-Automatic: If the control pressure/vacuum is too low and the valve does not open automatically, it can be opened manually by lifting the built-in lever arm and setting the latch. The latch resets automatically when control pressure rises enough to release it.

M2582-P is for 1-inch (25 mm) gas lines. It automatically opens at 5 psi (35kPa) [0.34 bar] and fully opens the seat at 15 psi (103 kPa) [1.02 bar]. The valve can be manually opened with the lever and latch against inlet pressure of 80 psi (552 kPa) [5.52 bar]. The latch will release after pilot pressure reaches 11 psi (17kPa) [.17 bar].

M5180-P is for 2-inch (52 mm) gas lines. It automatically opens at 5 psi (35kPa) [0.34 bar] and fully opens the seat at 15 psi (21 kPa) [.21 bar]. The valve can be manually opened with the lever and latch against inlet pressure of 100 psi (689 kPa) [6.89 bar]. The latch will release after pilot pressure reaches 11 psi (17kPa) [.17 bar].