Preset-

Slam Shut off valve is installed immediately after the filter & prior to the Regulator. It normally remains open, incase the outlet pressure of the regulator exceeds the premissible limits, the slam shut off valve senses it through the impulse line & immediately shuts off the flow to downstream. When the regulator is repaired, the slam shut of valve is to be opened manually by pulling the knob. Once the flow starts through the slam shut off valve it will remain open till the outlet pressure of the regulator is within limits.