During testing, the hold time for 85-100 psi in a properly functioning dual air system should be what duration?

During testing, the hold time for 85-100 psi in a properly functioning dual air system should be what duration?

• A. 15 seconds
• B. 45 seconds
• C. 60 seconds
• D. 90 seconds

Answer: (B)

Holding the system in the 85-100 psi range for a set period tests for leaks and overall integrity of the dual air brake system. In a properly functioning setup, once the compressor has built up to operating pressure, the pressure should stay within that window for 45 seconds. This duration is long enough to reveal slow leaks in lines, fittings, or valves, yet short enough to be practical during inspection. If pressure were to drop below 85 psi before the 45-second mark, it indicates a leak or faulty component in one of the circuits. The pressure should be regulated so it doesn’t stray beyond 100 psi, which would point to an issue with the governor or safety valves. So, 45 seconds is the standard hold time used to confirm the system remains steady and leak-free in the 85-100 psi range.