Patent ID: 9677964
Date: 2017-06-13
CPC Classifications: G01L

Claim:
1. A method for detecting contamination of the diaphragm of a capacitance diaphragm gauge (CDG) that includes a diaphragm and at least one fixed electrode wherein the capacitance between the diaphragm and the fixed electrode is responsive to a pressure applied to the CDG, the method comprising: applying a first pressure to the CDG; determining a first pressure value while the first pressure is applied to the CDG; applying a DC voltage between the diaphragm and the at least one fixed electrode of the CDG to cause deflection of the diaphragm, the DC voltage applied while the first pressure is applied to the CDG; determining a second pressure value while the DC voltage is applied between the diaphragm and the at least one fixed electrode of the CDG; comparing the second pressure value with the first pressure value to determine a difference in pressure values resulting from the deflection caused by the applied DC voltage; and determining that the diaphragm of the CDG is contaminated when the difference in pressure values is less than an acceptable difference in pressure values.