- AThey are too expensive
- They can cause an explosion when mixed with refrigerant oil
- CThey are not available in cylinders
- DThey provide insufficient pressure
Correct answer
They can cause an explosion when mixed with refrigerant oil
Why
Oxygen mixed with refrigerant oil can create an explosive mixture. Always use dry nitrogen for pressure testing.
The concept behind this question
The hazards on this exam are the ones that actually injure technicians. Refrigerants displace oxygen in confined spaces, so asphyxiation is a genuine risk in a mechanical room with a leak. Liquid refrigerant causes frostbite on skin and eye contact, so gloves and eye protection are not optional. Never charge with an open-flame or heat source nearby, never use compressed air or oxygen to pressure-test, and never exceed a cylinder's fill limit — cylinders are filled to 80% by weight precisely so there is room for liquid to expand.
More questions on this topic
- What are the two factors that, if present, are most likely to lead to an explosion with hydrocarbon refrigerants?
- What hazard exists when using nitrogen to pressurize a system for leak testing?
- What should you do if a large refrigerant leak occurs in an enclosed space?
- What personal protective equipment should be worn when handling refrigerants?
- What type of equipment should be used to detect refrigerant leaks?
- What is the danger of applying an open flame to a refrigerant leak?
Exam-style practice question. Not an official EPA exam question.