How does one conduct an Air Flow Method Brake Leakage Test?

How does one conduct an Air Flow Method Brake Leakage Test?

• A. Charge the brake system to at least 75 psi; air flow must not exceed 60 CFM.
• B. Charge the brake system to 75 psi; air flow must not exceed 75 CFM.
• C. Charge to 60 psi; air flow must not exceed 75 CFM.
• D. Charge to 75 psi; air flow must not exceed 60 CFM. If air flow does exceed 60 CFM, inspect train for leakage and retest.

Answer: (D)

The key idea is to measure how much air leaks from the brake system under a fixed pressure. In an Air Flow Method Brake Leakage Test, you charge the system to 75 psi and use an air flow meter to gauge the rate of air loss at that pressure. The allowable leakage is 60 cubic feet per minute or less. Keeping the pressure at 75 psi provides a stable reference so the reading reflects true leakage rather than pressure fluctuations. If the measured air flow exceeds 60 CFM, it indicates leaks somewhere in the train’s braking system—such as hoses, fittings, lines, reservoirs, or components—and you must inspect the train for leaks, repair, and then retest to ensure the rate is within the limit.

The key idea is to measure how much air leaks from the brake system under a fixed pressure. In an Air Flow Method Brake Leakage Test, you charge the system to 75 psi and use an air flow meter to gauge the rate of air loss at that pressure. The allowable leakage is 60 cubic feet per minute or less. Keeping the pressure at 75 psi provides a stable reference so the reading reflects true leakage rather than pressure fluctuations. If the measured air flow exceeds 60 CFM, it indicates leaks somewhere in the train’s braking system—such as hoses, fittings, lines, reservoirs, or components—and you must inspect the train for leaks, repair, and then retest to ensure the rate is within the limit.