Bakeable Absolute Pressure Gauge for the Millimeter of Mercury Range

A bakeable absolute pressure gauge which uses the compression of a gas in a precision bore glass tube by a piston of known weight is described. The measurement of the compression is accomplished by means of an electronic timing circuit. Equations are given for the design of the gauge and its accuracy under various operating conditions. Comparison is made between pressures measured by the gauge and pressures measured by liquid manometers.