As long as an oil is not flammable at the starting and ending temperature it can be used because the system is contained.

• A. True
• B. Only if the oil is AB
• C. Only if the system uses R134a
• D. False

Answer: (D)

Flammability risk in a refrigeration system isn’t determined by just whether the oil isn’t flammable at two specific temperatures. Even if the oil appears nonflammable at the start and end temperatures, the system can still encounter ignition risks during operation. Heat sources such as electrical components, hot surfaces, or mechanical friction can raise temperatures beyond safe points. Leaks or spills can create flammable mixtures with refrigerants, and the oil’s flammability can shift with changes in temperature, pressure, and the presence of refrigerants or air. The fact that a system is contained doesn’t remove the possibility of ignition or fire, so you cannot assume it’s safe simply based on those two temperature checks. In short, the statement is not a reliable safety rule; proper assessment requires considering the actual operating conditions, materials involved, and applicable safety guidelines.