Which is the maximum allowable leakage at the exhaust port of the purge valve on the air dryer?

The maximum allowable leakage at the exhaust port of the purge valve on the air dryer is specified to be one inch soap bubble every second. This standard ensures effective operation of the air dryer, which is crucial for maintaining proper air brake function. The allowable leakage rate is designed to signal that the system is functioning correctly without excessive leakage, which could indicate potential issues in the air system.

When a soap bubble forms within this rate, it indicates that the purge valve is sealing adequately under pressure and is not excessively leaking compressed air. If the leakage were greater than this standard, it could compromise the efficiency of the air dryer, leading to moisture accumulation in the air brake system, which could ultimately affect braking performance and safety.

In contrast, more stringent options, such as no leakage allowed or a solely timed basis for bubble formation (like every three seconds or more), are not practical or reflective of industry standards. They would impose unrealistic conditions that do not align with everyday operational tolerances for air dryers in heavy-duty vehicle applications. The acceptable leakage of one inch every second balances functionality with reasonable wear and tear considerations on the system.