LECO 736 Series Inert Gas Fusion analysis of Oxygen and Nitrogen

Transform the determination of oxygen and nitrogen in inorganic materials, ferrous and nonferrous alloys, and refractory materials with the LECO ON736 Series elemental analyzer. Designed for accuracy, reliability, and ease of use, the ON736 combines high-performance detector technology with LECO’s intuitive Cornerstone® touch-screen software. A range of optional, customizable features allows laboratories to configure the system to match specific analytical and productivity requirements.

Available Models

The ON736 Series is available in multiple configurations to support different analytical needs:

• ON736 – Oxygen and Nitrogen Analyzer
• N736 – Nitrogen Analyzer
• O736 – Oxygen Analyzer

Key Features and Benefits

The ON736 Series is engineered to deliver precise results, high uptime, and efficient laboratory workflows:

• High-performance detector design

  • Thermostatically controlled construction protects against ambient temperature fluctuations
  • Optimized emitter control and detection circuitry for long-term stability

• Flexible carrier gas options

  • Choice of helium or argon carrier gas to match application and cost requirements

• Automation for increased productivity

  • Optional autocleaner reduces the need for manual cleaning between analyses
  • 20-position shuttle loader for crucibles and samples supports unattended operation

• Ergonomic, operator-focused design

  • Boom-mounted touch-screen interface improves accessibility and ease of use
  • Cornerstone® software provides intuitive control and real-time system feedback

• Advanced detection technology

  • Non-dispersive infrared (NDIR) detection for oxygen
  • Thermal conductivity (TC) detection for nitrogen
  • No moving parts and no manual detector adjustments required

LECO 736 Series

Applications

The ON736 Series is ideally suited for a wide range of inorganic and metallurgical applications, including:

• Inorganic materials
• Ferrous and nonferrous alloys
• Copper and aluminum
• Refractory materials

Theory of Operation

The ON736 Oxygen/Nitrogen system is designed for the simultaneous determination of oxygen and nitrogen in steel and other inorganic materials using the inert gas fusion technique. The analyzer is controlled by custom Cornerstone® software optimized for touch-screen operation.

A pre-weighed sample is placed into a graphite crucible and heated in an impulse furnace. During heating, oxygen present in the sample reacts with the graphite crucible to form carbon monoxide (CO) and carbon dioxide (CO₂). An inert carrier gas, typically helium, sweeps the released gases from the furnace through a mass flow controller and into the detection system.

The gas stream passes through a heated reagent where CO is oxidized to CO₂ and hydrogen is oxidized to form water (H₂O). Oxygen is measured as CO₂ using a non-dispersive infrared (NDIR) detector. The CO₂ and H₂O are then removed from the carrier gas stream, leaving nitrogen as the remaining analyte.

Nitrogen is detected using a thermal conductivity (TC) detector. TC detection is based on the difference in thermal conductivity between the carrier gas and nitrogen. Heated filaments respond to changes in heat transfer as nitrogen enters the gas stream, producing a measurable electrical signal.

Sample concentrations are calculated relative to calibration standards. To minimize the effects of instrument drift and ensure consistent accuracy, reference measurements of pure carrier gas are performed prior to each analysis.