When brazing copper refrigerant lines during an HVAC system installation, what is the primary purpose of flowing a low-pressure, inert gas like nitrogen through the tubing?
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A
To cool the copper tubing and prevent overheating.
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B
To purge any residual refrigerant from the lines.
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C
To displace oxygen and prevent the formation of copper oxide scale inside the pipe.
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D
To increase the pressure inside the pipe to test the brazed joint as it cools.