During Brake Pipe Leakage Method, after waiting one minute, what must be done next?

During Brake Pipe Leakage Method, after waiting one minute, what must be done next?

• A. Cut-out the automatic brake valve
• B. Increase pressure by 20 psi
• C. Time the leakage for two minutes
• D. Stop the test

Answer: (A)

The test aims to measure brake pipe leakage by isolating the brake pipe from the rest of the system after a short stabilization period. After one minute of holding the test pressure, you must cut out the automatic brake valve. This stops any further air from being fed into the brake pipe, so the pressure drop you observe reflects only leakage in the system, not input from the compressor or valve. Increasing pressure, timing for two minutes, or stopping the test would not preserve a valid leakage measurement, so isolating the brake pipe is the correct next step.

The test aims to measure brake pipe leakage by isolating the brake pipe from the rest of the system after a short stabilization period. After one minute of holding the test pressure, you must cut out the automatic brake valve. This stops any further air from being fed into the brake pipe, so the pressure drop you observe reflects only leakage in the system, not input from the compressor or valve. Increasing pressure, timing for two minutes, or stopping the test would not preserve a valid leakage measurement, so isolating the brake pipe is the correct next step.