how to put the gauges on and off the ac system without contaminating the system.
I realize this method may be different than you may have learned. Be sure and watch all 4 parts of this series to see why.
This is the fastest simplest way to remove the gauges without contamination.
HVAC 042 B    • HVAC 042B part 2 bleeding across the ...  
HVAC 042 C    • HVAC 042C Part 3 Manual low loss valv...  
HVAC 042 D    • HVAC 042D Part 4 Purging the hoses be...