Limiting Oxygen Index
Limiting Oxygen Index - Silver Series

Oxygen Index Apparatus

ASTM D2863, ISO 4589, BS 2782 part 141

The Limiting Oxygen Index (LOI) fire test is perhaps the most economical and precise quality control test for combustible materials. Its ease of use together with high levels of precision has made this technique a primary characterization and quality control tool for the plastic materials and electric cable industries. It is often used in materials specifications and material/product data sheets and included in some US Mil Specs. The test assesses the minimum percentage of oxygen in the test atmosphere that is required to marginally support combustion.

The 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.

While many designs of the LOI test apparatus calculate oxygen index based on the flow of oxygen and nitrogen, the unit incorporates a paramagnetic oxygen analyzer for precise measurement of oxygen concentration without the need for calculations and frequent recalibrations.


  • Paramagnetic Oxygen Analyzer for assessing accurate oxygen (± 0.1%) levels.
  • Glass test chimney: 450 mm x 75 mm
  • Igniter wand
  • Automatic flow control gives oxygen level adjustment by turning one single valve.
  • Digital display of oxygen percentage in atmosphere during test (no calculations needed).
  • Digital display of temperature of gas mixture entering the test chimney.
  • Quick loading of sample into test chimney.
  • Sample holders for both rigid and flexible samples supplied.
  • One pack of 10 clear PMMA calibration samples (Oxygen Index: 17.4) supplied.


  • Digital readout for oxygen concentration: +/- 0.1%
  • Dimensions (mm): 350(W) x 370(D) x 280(H)
  • Column size (mm): 75 & 100(dia) x 450(H)
  • Weight (kg): 14
  • Voltage: 230V 50Hz 1A or 110V 60Hz 2A
  • Operating Manual: Supplied
  • Other Service requirements: Bottled O2/N2, Propane

Limiting Oxygen Index - Silver Series 

ASTM D2863

The Limiting Oxygen Index Apparatus is used to determine the minimum oxygen in a flowing mixture of oxygen and nitrogen for flaming combustion. The oxygen tester is used to check combustion of plastic materials such as polymers, cables, rubber, nylon, laminates, fabrics etc. The percentage of Oxygen required for specimen to burn without any existence of flame is displaced digitally with the help of Paramagnetic Oxygen sensor and analyzer.


Silver Series

  • Micro adjustment gas flow meters to indicate flow of oxygen, nitrogen and mixture of gas to ±1% accuracy
  • Gas pressure gauges to indicate the pressure of oxygen and nitrogen (range 0-100 psi) least-count
  • Gas dispersion in chimney is through circulation inside a hollow cylinder placed at the bottom of the gas chimney
  • % limiting oxygen value is displayed with the help of digital oxygen meter. No need to calculate the limiting oxygen value by observing the volumes from the gas flow meter.
  • Accuracy: ±0.5%.
  • Resolution: 0.1%
  • The equipment can be used to carry out temp. index
  • Heaters provided of 1KW capacity and protection through solid relay is a standard feature
  • PID temp. controller of accuracy ±0.2oC

For more information about Limiting Oxygen Index Chamber, please call us at 1.877.884.8378 or Click the button below.