Digital Gauges (Reading in -psi)
Many technicians are beginning to use Digital Gauges. While it is ok to use Digital Gauges it is important that the technician understand the difference between PSI and inHg (Inches Mercury) when the unit is in a vacuum.
To make it simple….
If the techs gauges cannot be set to read (inHg). They need to double the psi reading when they enter the value into the Low Side Pressure portion of the checklist, if the Low Side is in a Vacuum!
Note: This only applies to (-) numbers which means vacuum.
Examples:
1psi = 1psi
10psi =10psi
-4psi = -8inhg
-12psi = -24inhg