Confused Reading of Pressure on Vacuum Gauge
Pressure gauges typically measure pressure relative to ambient, so &quot;0&quot; on a gauge means equal to ambient (~ 1 bar absolute pressure depending on where you are). In some cases, the units have a &quot;g&quot; at the end, for example &quot;psig&quot; to indicate that the measure is &quot;gauge pressure&quot; rather than absolute, but that isn't always the case.