What instrument is used to verify the removal of ambient air prior to brazing in piping?

• A. oxygen analyzer
• B. air analyzer
• C. nitrogen analyzer
• D. breathalyzer

Answer: (A)

Removing ambient air before brazing relies on confirming that the environment inside the joint has become oxygen-free. An oxygen analyzer directly measures how much oxygen remains, so it tells you when the purge has displaced the air sufficiently and you’ve achieved the inert atmosphere needed for a clean brazed joint. When the purge gas has driven out the air, the oxygen level falls to a very low value, signaling it’s safe to proceed with brazing and less risk of oxidation or oxide contamination. Other instruments detect different things—measuring nitrogen won’t tell you the presence of residual oxygen, a generic air analyzer is not specific to oxygen content, and a breathalyzer has no relevance to piping or brazing. So, the oxygen analyzer is the best choice for verifying removal of ambient air.