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Oxygen Index

ASTM D2863; BS ISO 4589-2; NES 714

The Oxygen Index is, perhaps, the most economical and precise quality control test of combustible materials. Its ease of use together with high levels of precision has made this technique a primary characterising and quality control tool to the plastic and electric cable industries and it has been specified by several military and transport groups. The technique measures the minimum percentage of oxygen in the test atmosphere that is required to marginally support combustion. Note that BS ISO 4589 supersedes BS 2782 Part 141.

The FTT unit has been designed to be compact for efficient use in a standard fume cupboard (or under a simple ventilation hood that we can also supply if required). The unit gives continuous digital readout of oxygen concentrations in the test atmosphere to facilitate quick settings of test concentration. Stabilised oxygen percentages are read from the digital readout and no additional flow adjustments are required. This is a considerable improvement over systems that use analogue gauges or require flow matching and the use of graphs or tables to calculate oxygen concentrations. This makes the unit as automatic as is feasible.

The Oxygen Index can be used in conjunction with the Elevated Temperature Oxygen Index apparatus (TOI) to determine the oxygen index at temperatures up to 125°C.


  • New Paramagnetic Oxygen Cell for assessing accurate oxygen (< 0.1%) levels
  • Compact unit for efficient use inside a laboratory hood, with ventilation
  • Automatic flow control gives oxygen level adjustment by turning one single valve
  • Quick loading of test specimen into test chimney measuring 450 mm × 75 mm
  • Digital display of oxygen percentage in atmosphere during test (no calculations needed)
  • Digital display of temperature of gas mixture entering the test chimney
  • Sample holders for both rigid and flexible samples supplied
  • Shortened gas path for rapid response


  • Digital readout for oxygen concentration: +/- 0.1%
  • Dimensions (mm): 350 (W) × 370 (D) x 280 (H)
  • Column size (mm): 75 & 95 (dia) × 450 (H)
  • Weight: 14 kg
  • Voltage: 230V 50Hz 1A or 110V 60Hz 2A
  • Operating Manual: Supplied
  • Other Service requirements: Bottled O2/N2, Propane
Oxygen Index

Oxygen Index

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