Auto-Ignition Temperature (AIT) Tester

Hazards Laboratory
Michigan Tech University
Room 207 Chemical Sciences
The AIT device consists of a furnace with controller and a 100 ml quartz flask. The flask is normally in the furnace, with the neck of the flask below the central hole in the furnace.
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Purpose

The purpose of the AIT tester is to determine the auto-ignition temperature (AIT). The AIT is the temperature at which a material will spontaneously combust in air, without an ignition source. The AIT is reported at 1 atm pressure.

In general, the AIT

  1. Decreases with increasing pressure.
  2. Increases as mixtures become rich or lean.
  3. Decreases with increased oxygen concentration.
  4. Decreases in the presence of catalytic surfaces (which may include rust) and in the presence of combustion sensitizers (such as NOx)

Operation

The AIT device is operated by heating the furnace to a fixed temperature, and then injecting the flammable liquid to be tested. If a combustion is not observed, then the temperature is increased until combustion does occur. A combustion occurs when a pale blue or yellow flame is observed.