Recreational Vehicle (RV) Technician Practice Test

Why is it important to avoid overfilling a propane cylinder?

1. To limit the weight

2. To prevent leaks

3. To avoid overpressure from expansion

4. To maintain gas quality

The correct answer is: To avoid overpressure from expansion

Avoiding overfilling a propane cylinder is crucial primarily because of the risk of overpressure from thermal expansion. Propane, like all gases, expands as it heats. If a cylinder is filled beyond the safe limit, there will not be sufficient space for the gas to expand as temperatures rise. This lack of necessary expansion space can lead to dangerously high pressure within the cylinder, which may cause the relief valve to operate, venting propane gas, or even result in a risk of rupture or explosion. While considerations such as weight, leak prevention, and gas quality are also important aspects of handling propane cylinders, they do not directly address the critical safety issue associated with thermal expansion and the pressure it can create within an overfilled cylinder. By ensuring that cylinders are filled to the appropriate level, technicians can help maintain safety and operational integrity when using propane.