Yes, the MKS 423 is affected by different gases because it is a gas dependent gauge. This gauge measures pressure based off of ionization properties 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.
Category: Instrumentation Gauging
Sub-Category: Cold Cathode Ion Gauges