Apparatus and methods for operating a dual chamber orifice fitting. The dual chamber orifice fitting comprises a body having a lower chamber and a top having an upper chamber. An aperture connects the upper chamber to the lower chamber. A closure member is pivotally mounted to the fitting and pivots about a first axis between a first position and a second position. A pivot arm is rotatably mounted to the body and engages the closure member so that rotation of the pivot arm about a second axis pivots said closure member about the first axis between the first and second positions.