When Pressurizing a Refrigeration System with Nitrogen?

When pressurizing a refrigerant system with nitrogen, what rule should you always follow? Blended refrigerants leak from a system: In uneven amounts due to different vapor pressures. Which of the following is not an approved technique of system cleanup after a burnout?

When can you use a disposable cylinder to recover refrigerant?

The internal pressure of the cylinders may rise in heated areas and cause an explosion. When can you use a disposable cylinder to recover refrigerant: Never.

Why must containers designated refillable by dot?

Why are containers designated "refillable" by DOT used for transporting recovered pressurized refrigerant? To meet safety requirements. When evacuating a system, the hoses should be: As short in length and as large in diameter as possible.