what the hell is wrong with PSI and inches of mercury?
/rant off...sorry.
EDIT: that rant was not aimed at you!...I reread that you want Torr, then yes, you should be able to calculate it with scaling math. You will also want to be able to adjust it if necessary when you first set up and verify/test the instrument.
In regards to PSI or inches of mercury. This unit of pressure measurement is not really used in this industry (Vacuum heat treating) for processing aircraft engine components.
IE..
Torr (or Millibar overseas) has a far greater readability.
1 ATM = 760 Torr (1013 Millibar),
1 ATM = 14.69 PSIA
As you can see, there is far more readability compared to PSI.
In the industry of Vacuum heat treating, heat treatment is commonly done at 10-1 Torr range and lower.
Vacuum brazing is done in the 10-4 to 10-5 Torr range. (Above 8x10-4 Torr and the braze joint is no good)
This gauge (2 types used, known as Convectron or Pirani) is the UPPER level in pressure.
The LOWER Level of pressure reading is an ION gauge (2 types used, known as Cold Cathode or Hot filament type) and the range of that gauge is 10-2 to 10-10 Torr.
Capacitance Manometers are also used and they are VERY accurate but only cover 4 decades of Torr and are the most expensive. They do not read very well below 10-5 Torr and are VERY expensive in this range.
The best feature about Capacitance Manometers is they are "true pressure gauges", meaning they are not affected by the type of "residual" gas (Argon, Nitrogen.....etc) or water vapor in the system.
Even the pumping systems used to attain these vacuum levels are dependent on certain ranges of vacuum. It usually takes 3 types of pumps to get to the 10-5 range.
I could go on and on and on....