When testing the vacuum system of a mixed gas with a heat conduction vacuum gauge, if the volume percentage Vi (i = 1, 2, 3, ..., n) of various gases in the mixed gas is known, the relative sensitivity S of mixed gas for the air can be calculated by the following formula.
Where: Vi—the volume percentage of the i-th gas;
Sri—the relative sensitivity of the i-th gas.
After calculating Sr, the result measured by the above method is multiplied by Sr to obtain the actual vacuum of the mixed gas.