Slam shut safety device

摘要

A safety device for a gas distribution system includes a valve body and an upper casing attached to the valve body, the upper casing housing two springs. The two springs are separated by a casting tube. The two springs are attached to a movable diaphragm that is exposed to gas system pressure. The valve body also includes a cam mounted within the valve body. A limit switch is directly connected to the cam such that the limit switch moves directly in response to movement of the diaphragm. Additionally, a reset pin extends from the valve body and interacts with the cam such that the cam may be reset from a closed position to an open position by moving the reset pin.

主权项

1. A slam-shut safety valve for a gas distribution system, the slam-shut safety valve comprising:
a valve body; an upper case mounted to the valve body; a diaphragm disposed between the valve body and the upper case, at least part of the diaphragm being displaceable into an interior portion of the valve body and into an interior portion of the upper case, the diaphragm having a first side being exposed to gas system pressure; a first spring and a second spring disposed within the interior of the upper case, the first spring and the second spring exerting respective first and second spring forces on a second side of the diaphragm opposite the gas system pressure; a plunger connected to the first side of the diaphragm; a cam rotatably mounted within the interior of the valve body, the cam having a first arm, a second arm, and a third arm, the first arm contacting the plunger; a latch engaging the first arm, the latch adapted to be connected to a slam-shut valve plug; wherein movement of the plunger either towards or away from the cam rotates the cam and releases the latch, the second cam arm is adapted to contact a limit switch, the limit switch moving longitudinally in response to rotation of the cam, and the limit switch extends outside of the valve body.