Which gas is commonly used for pressure testing refrigerant systems due to its safety?

Nitrogen is the gas commonly used for pressure testing refrigerant systems, primarily due to its safety and inert properties. When performing pressure tests, it is crucial to use a gas that will not react with refrigerants or other system components, ensuring that no hazardous situations arise during the testing process.

Nitrogen is an inert gas that does not support combustion, making it safe to use in various environments, avoiding the risks associated with flammable gases. Furthermore, it is readily available, inexpensive, and does not pose health risks when handled properly. This attribute makes nitrogen the preferred choice for technicians conducting pressure tests.

Other gases listed, such as hydrogen, oxygen, and carbon dioxide, present specific risks. Hydrogen is highly flammable and can pose explosion risks; oxygen supports combustion and could lead to fire hazards; and carbon dioxide can be hazardous in high concentrations, potentially leading to asphyxiation. These factors highlight why nitrogen is the safest and most suitable choice for pressure testing in refrigerant systems.