Which of the following safety precautions is critical when servicing oxygen systems?

Maintaining cleanliness and avoiding contact with oils or grease is critical when servicing oxygen systems because oxygen is a highly reactive element, and the presence of contaminants such as oils or greases can create a fire hazard. When oxygen is pressurized, it can react violently with combustible materials, potentially leading to dangerous fires or explosions. This risk is heightened because the presence of oxygen facilitates combustion, making what might typically be a non-flammable substance ignite under the right conditions.

Proper handling and servicing of oxygen systems require technicians to ensure that equipment and their own hands are free from any contaminants that could pose a risk. Therefore, strict cleanliness protocols must be followed to help prevent any dangerous reactions and ensure safety during servicing.

The other options all present significant safety risks; using petroleum-based oil can similarly lead to combustion reactions when in contact with high concentrations of oxygen, and smoking near the service area poses an obvious ignition risk. Withholding service from outdoor environments might seem like a precaution, but it does not address the fundamental risks posed by oils and greases in the servicing process. Thus, avoiding contact with oils and grease while maintaining cleanliness is paramount in the safe handling of oxygen systems.