| 摘要 |
A vent plug assembly for relieving overpressure from within an instrument casing and comprising a body adapted for secured placement within an aperture defined in the exterior wall of the casing and having a thru-bore and a blind recess symetrically spaced apart and of like configuration and internal cross-sectional dimension. A cooperating plug having a top plate and a pair of dependent stubs of like cross-sectional configuration and spacing as the thru-bore and recess of said body is interchangeably insertable within the thru-bore and recess of the body with one of the stubs defining a blind upward recess and the other of said stubs defining a thru-bore. The plug is interchangeably displaceable manually such that when the respective thru-bore of the body and plug are interfitted, continuous venting occurs while when the blind recess stub of the plug is inserted in the thru-bore of the body, venting occurs only at a predetermined value of pressure build-up from within the casing sufficient to expel the assembly from the installed aperture of the casing.
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