A technician is recovering R-407C from a contaminated system that previously experienced a burnout. The recovery cylinder is equipped with two dip tubes (liquid and vapour ports). What specific recovery method would be most effective for this scenario?

Question: A technician is recovering R-407C from a contaminated system that previously experienced a burnout. The recovery cylinder is equipped with two dip tubes (liquid and vapour ports). What specific recovery method would be most effective for this scenario?

Answer options: ✅ Liquid recovery through the liquid dip tube, followed by vapour recovery through the vapour port, and continued recovery until a deep vacuum is achieved.

• Vapour recovery only, to avoid pulling solids into the recovery machine.
• Push-pull method, connecting both liquid and vapour lines to the system.
• Only recover enough to temporarily fix the system, then return later.

Correct answer: Liquid recovery through the liquid dip tube, followed by vapour recovery through the vapour port, and continued recovery until a deep vacuum is achieved.

Explanation: For contaminated systems, it's crucial to remove both liquid and vapour. Starting with liquid recovery is faster, and then switching to vapour recovery to evacuate residual refrigerant down to a deep vacuum (e.g., 500 microns) is essential to remove all contaminants and non-condensables, as required by good recovery practices and CEPA regulations.