What type of gas is commonly used to pressure test a refrigeration system?

Nitrogen is commonly used to pressure test refrigeration systems because it is an inert gas that does not react with the components of the system. This makes it safe to use without the risk of causing chemical reactions that could damage the system or create hazards. Additionally, nitrogen is readily available and cost-effective, which makes it a practical choice for technicians when performing pressure tests.

During a pressure test, nitrogen is pressurized within the system to check for leaks. If there are any leaks, the pressure will drop, indicating an issue that needs to be addressed. Unlike some other gases, nitrogen will not condense at the temperatures typically involved in refrigeration, making it suitable for thoroughly testing the system without altering its states.

The other gases mentioned may have specific applications but are not ideal for pressure testing in refrigeration systems. For instance, helium is expensive and used for leak detection due to its low density and ability to escape easily through small openings, but it is not routinely used for pressure testing. Oxygen is not suitable due to its reactive nature and potential to cause combustion in the presence of other materials. Carbon dioxide can create high pressure but is typically not used for the same reasons as nitrogen.