Reliability of a capacitance manometer in the range 2×10−4−5×10−6 Torr

A capacitance manometer has been tested and compared to the method of volumetric pressure division using helium as a working gas in the range 2×10−4−5×10−6 Torr. The results show that the unit tested was linear to the lowest pressures utilized, and the two methods were in agreement to about 0.6% plus 4×10−7 Torr, in addition to the errors introduced by the least count of the capacitance manometer’s digital readout. Argon and air gave similar results.