What are the maximum leakage rates in the semis air braking system?

most trucks run air pressure between 90 and 120 lbs.in an air leak test this pressure should not drop below 60 lbs in less than a minute. air should also not drop below 60 lbs when brakes applied. however, there is a safety on air brakes that will slam brakes on when air does drop below safety pressure,usually 60 lbs. as well as this the safety can be set higher so buzzer and lights alert you,and you generally will have time to get off the road before you vehicle is immobilzed by no air pressure