Before beginning a DP Brake Pipe Communications Test, what air flow condition must be confirmed for each consist?

Before beginning a DP Brake Pipe Communications Test, what air flow condition must be confirmed for each consist?

• A. Air flow is irrelevant for this test.
• B. Determine the air flow on each consist is below 20 CFM, or has remained stable for 90 seconds.
• C. Air flow must be above 50 CFM on all consist.
• D. Air flow must be exactly 20 CFM.

Answer: (B)

Before starting the DP Brake Pipe Communications Test, you need to verify the air flow condition in each consist. The test relies on a stable, low movement of air in the brake pipe so the communication signals aren’t distorted by airflow. The required condition is that the air flow on each consist is either below 20 cubic feet per minute (CFM) or has remained stable for 90 seconds. If the flow is too high, or if it’s fluctuating, those changes can interfere with the test signals and make the results unreliable. So this check ensures the environment is quiet enough for accurate communication testing.

Before starting the DP Brake Pipe Communications Test, you need to verify the air flow condition in each consist. The test relies on a stable, low movement of air in the brake pipe so the communication signals aren’t distorted by airflow. The required condition is that the air flow on each consist is either below 20 cubic feet per minute (CFM) or has remained stable for 90 seconds. If the flow is too high, or if it’s fluctuating, those changes can interfere with the test signals and make the results unreliable. So this check ensures the environment is quiet enough for accurate communication testing.