Which device should be used to verify the effectiveness of a nitrogen purge before brazing?

The effectiveness of a nitrogen purge before brazing is critical for ensuring that the brazing process occurs in an oxygen-free environment, which helps prevent oxidation and other defects. An oxygen analyzer is the appropriate device for this purpose because it specifically measures the concentration of oxygen in the environment being purged.

Through the use of an oxygen analyzer, technicians can ascertain whether the nitrogen purge has successfully reduced the oxygen levels to an acceptable threshold before proceeding with brazing. This measurement ensures that the atmosphere within the system is suitable for the process, thus safeguarding the integrity and quality of the brazed joints.

While other devices like pressure gauges, flow meters, and thermometers are valuable tools in various applications, they do not provide a direct assessment of oxygen concentration. A pressure gauge measures the pressure within a system, which does not indicate the purity of the nitrogen purge. A flow meter assesses the flow rate of the nitrogen gas but does not indicate how effectively it has displaced oxygen. A thermometer measures temperature but is unrelated to the presence of oxygen. Hence, the oxygen analyzer is the most relevant and effective device for verifying the nitrogen purge's effectiveness before brazing.