Oxygen, Nitrogen, and Hydrogen Analysis

概要

The LECO 736 Series delivers precise oxygen and nitrogen measurements in metals and alloys using advanced inert gas fusion and thermostatic detection. With automation-ready options, argon carrier gas compatibility, and a robust design, it streamlines metallurgical quality control, improves throughput, and lowers operating costs, while ensuring every result meets the highest standards for accuracy and reliability.

Building on these capabilities, the LECO 836 Series takes elemental analysis even further. In addition to oxygen and nitrogen, it integrates simultaneous hydrogen detection for comprehensive ONH analysis in a single system. The 836 Series also offers expanded detection capabilities and enhanced built-in automation, giving laboratories the tools to accelerate workflows, reduce costs, and achieve unmatched precision and dependability across all three elements.

How LECO ONH Analyzers Work

The LECO 736 and 836 Series elemental analyzers use inert gas fusion to deliver precise, simultaneous measurement of oxygen and nitrogen (736), with the 836 extending capabilities to include hydrogen for full ONH analysis. Both systems are designed for steel, refractory metals, and other inorganic materials, and feature intuitive, touch-optimized software to streamline laboratory workflows.

In each system, a pre-weighed sample is placed in a graphite crucible and heated in an impulse furnace. As the sample melts, oxygen reacts with the graphite to form carbon monoxide (CO) and carbon dioxide (CO₂), while nitrogen and hydrogen are released as elemental gases. An inert carrier gas (typically helium or argon) sweeps the liberated analytes from the furnace through a mass flow controller and into the detection system.

Gas handling and detection are based on a combination of non-dispersive infrared (NDIR) and thermal conductivity (TC) technologies. NDIR cells measure oxygen-related species by detecting CO and CO₂, and H₂O on the 836 Series, at their characteristic infrared absorption wavelengths. As the gas stream passes through heated reagents, CO is fully oxidized to CO₂ and hydrogen is converted to H₂O, ensuring accurate, wide-range detection across different materials and concentrations.

After CO₂ and H₂O are removed from the gas stream, nitrogen remains as the final analyte and is measured using a thermal conductivity detector. TC detection relies on differences in thermal conductivity between the carrier gas and analyte gases, producing a measurable signal as nitrogen alters heat transfer across heated filaments. The 836 further enhances accuracy with a patented Dynamic Flow Compensation (DFC) system, which maintains consistent carrier gas flow despite gas losses during scrubbing.

For both analyzers, elemental concentrations are calculated relative to calibration standards. To minimize drift and ensure long-term stability, reference measurements of pure carrier gas are performed prior to each analysis—delivering reliable, repeatable results for demanding metallurgical and materials testing applications.

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