The GW MJC is a one directional inline valve, single or double outlet, held closed by a frangible glass bulb heat sensitive element. All MJCs are marked with the direction of the water flow cast on the body.
When sufficient heat is applied to the glass bulb shatters and releases the link mechanism allowing water to flow (similar to the function of an automatic sprinkler).
Electrically actuated MJCs are fitted with a Metron actuator. When an electrical current is applied to the actuator a piston is propelled from the Metron body breaking the frangible glass bulb.