Normally Open (N.O.)
There is no electrical absorption during normal operation and so no part of the system undergoes wear; there

Normally Closed (N.C.)
The intrinsic accuracy of these models guarantee that gas will be cut off should the power supply fail.
Consequently, a permanent power supply is required to keep the valve open. As soon as power across the coil
is cut off, the valve shuts automatically

Automatic
Automatic gas solenoid valves are used for safety and control of gas for shut-off in gas feed pipes.