Vacuum gauge that works inside the vacuum?

[PaulMarcel]

I have a chamber vacuum sealer that has several special modes that I'd like to map out with numbers plus how strong is the vacuum for regular and 'strong' mode?

The gauges I've used and seen all rely on measuring the difference between the ambient air pressure around the gauge and the vacuum in a tube.

I'd need a gauge that could go in the chamber and read the vacuum level. I'm also wondering if, thinking aloud, I took a regular gauge and sealed off the port that usually goes to the vacuum, would it show the difference between ambient (the vacuum) and what's in the sealed tube? I dunno.

 

[kevinculle]

An ordinary pressure gauge located in a low-pressure zone and with the pressure tap plumbed to outside atmospheric pressure will show the vacuum (pressure difference to atmosphere) as a positive reading.  You just need a gage with the right scaling...15 PSI is right for a hard vacuum.