Recreational Vehicle (RV) Technician Practice Test

A propane lock up test requires what percentage of vapor flow?

1. 25 percent

2. 50 percent

3. Zero percent

4. 75 percent

The correct answer is: Zero percent

In a propane lock-up test, it is essential to ensure that the gas supply system is functioning correctly and safely. The purpose of this test is to check the pressure in the system when it is subjected to a complete shut-off condition. A zero percent vapor flow indicates that the system is effectively sealed and that there is no gas moving through it. During the test, if the propane system is not allowing any vapor flow, it reflects that the shut-off valve is functioning as intended, preventing any gas leak or unintentional discharge. This condition is necessary to evaluate the integrity of the system and determine if it holds pressure adequately without any gas escaping. When assessing the various percentages of vapor flow, a zero percent reading specifically confirms that the system is not allowing any propane to pass through, ensuring safe operation. Understanding the lock-up test is critical for RV technicians, as it relates to the safety and reliability of propane systems in recreational vehicles.