Yes, the MKS 390 is affected by different gases because it is a gas dependent gauge once is transitions to the pirani or hot filament ion gauge technology. These portions pressure based off of ionization properties (ion gauge) and thermal conductivity (pirani) of the specific gas. Since these gauges are calibrated in N2 (like all other gauges), any gas other than air or N2 will cause the measurement to be skewed. This can be corrected by using a gas calibration factor, or GCF. Common GCFs can be found in the manual. Some of these GCFs can be applied within the gauge itself and others need to be applied manually. The piezo portion of this gauge (measuring from ATM to 10 Torr) is NOT affected by different gases as this gas is a gas independent technology.
Category: Instrumentation Gauging
Sub-Category: Wide-Range Combination Gauges