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Refrigeration & Air Conditioning Mechanic Red Seal · Question

What is the primary reason for maintaining a positive flow of nitrogen inside refrigeration tubing during brazing operations?

Nitrogen purging during brazing prevents the formation of copper oxides (black scale) on the inside of the tubing. This scale can detach, circulate with the ref

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Question: What is the primary reason for maintaining a positive flow of nitrogen inside refrigeration tubing during brazing operations?

Answer options:

  • To rapidly cool the brazed joint ✅ To prevent oxidation and scale formation on the internal surfaces
  • To increase the strength of the brazed joint
  • To purge all residual refrigerant before brazing

Correct answer: To prevent oxidation and scale formation on the internal surfaces

Explanation: Nitrogen purging during brazing prevents the formation of copper oxides (black scale) on the inside of the tubing. This scale can detach, circulate with the refrigerant, and cause blockages or damage to expansion valves and compressors, as per standard industry practice and CSA B52 guidelines for system cleanliness.

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