Combined pressure relief and indicator mechanism

A combined pressure relief and pressure indicating mechanism for a vented housing filled with fluid at super-atmospheric pressure, comprising:

• rupturable diaphragm means for normally closing the vent, the diaphragm means being normally maintained in a first configuration as long as the fluid pressure is below a first value, and moving out of the first configuration into a second configuration when the fluid pressure exceeds the first value;
• puncturing means for puncturing the diaphragm in response to movement of the diaphragm out of the first configuration and toward the second configuration;
• and
• a normally unobservable movable indicator biased to an observable position, the indicator being normally held by the diaphragm means in the unobservable position as long as the fluid pressure is greater than a second value and being released for movement to the observable position in response to fluid pressure less than the second value, the second value being less than the first value.

A combined indicator-relief mechanism for use with a dielectric-gas-pressurized high-voltage circuit interrupting device, the mechanism being of the type which automatically relieves an overpressure of the gas by venting the gas to atmosphere, and which gives an indication of an underpressure of the gas, the mechanism comprising:

• an apertured frame movable relative to the device;
• bellows means having a spring rate and interconnecting the frame to an opening in the interrupter and communicating the gas pressure to the aperture;
• piercing means mounted for relative movement toward the diaphragm between the aperture and the opening;
• means for normally deforming the diaphragm toward the opening and for preventing relative movement of the piercing means toward the diaphragm, an overpressure of the gas disabling the deforming means to evert the diaphragm and to relatively move the piercing means against the diaphragm so that upon piercing thereof, the gas is vented to the atmosphere;
• a normally unobservable indicator;
• means for biasing the indicator toward a visually observable position;
• and
• means for normally maintaining the indicator in the unobservable position against the action of the biasing means and for releasing the indicator to the action of the biasing means in response to movement of the frame caused by movement of the bellows incident to an underpressure of the gas.

A combined pressure relief and pressure indicating mechanism for a vented housing containing a fluid, comprising

• diaphragm means for normally closing the vent;
• means for puncturing the diaphragm means to relieve an excessive overpressure in the housing;
• and
• a movable indicator biased toward a first position, the indicator being normally held by the diaphragm means in a second position as long as fluid pressure exceeds a predetermined minimum, the indicator being released for movement to the first position if the fluid pressure is less than the minimum.