| http://www.w3.org/ns/prov#value | - When the gas line valve is subjected to violent movements such as might occur during earthquakes of a predetermined magnitude which may rupture or break the gas supply line leading to gas utilities or appliances, a recess which retains the ball valve on the ramp will be overcome by the violent movements and the ball valve will be moved onto the valve seat and be held in sealed relation on the valv
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