Abstract: An apparatus which is provided for closing a fluid valve in response to initial movement, as for example caused by a seismic disturbance, which is removably mountable to existing inline valves, such as gas valves. The apparatus includes a trigger which is responsive to seismic movement, particularly at a resonant frequency, to release a pressurized fluid supply which in turn drives a mechanical actuator to actuate the subject valve through the existing valve coupling. The existing valve coupling is typically a valve stem which must be rotated approximately ninety degrees from an open position to a closed position. The pneumatic drive is sufficiently powerful to actuate valves which are noticeably difficult to actuate manually. The force required to actuate the trigger mechanism is independent of the force required to actuate the valve, in accordance with the invention.

Abstract: An apparatus which is provided for closing a fluid valve in response to initial movement, as for example caused by a seismic disturbance, which is removably mountable to existing inline valves, such as gas valves. The apparatus includes a trigger which is responsive to seismic movement, particularly at a resonant frequency, to release a pressurized fluid supply which in turn drives a mechanical actuator to actuate the subject valve through the existing valve coupling. The existing valve coupling is typically a valve stem which must be rotated approximately ninety degrees from an open position to a closed position. The pneumatic drive is sufficiently powerful to actuate valves which are noticeably difficult to actuate manually. The force required to actuate the trigger mechanism is independent of the force required to actuate the valve, in accordance with the invention.