Label and Heat Shrink Printers

Heat Guns

The Limiting Oxygen Index (LOI) is a measure of the ratio of Oxygen to other gases in the air surrounding a substrate.

Normal atmospheric air (i.e. the air we breathe) is approximately 21% Oxygen, so a material with an LOI of less than 21% would burn easily in air. That being said, a material with LOI of greater than 21% but less than 28% would be considered "slow burning". A material with LOI of greater than 28% would be considered "self-extinguising". A self-extinguishing material is one that would stop burning after the removal of the fire or ignition source.

Here are some typical values for LOI of some popular plastic materials

Polyethylene, Polypropylene: 17.4%

PET: 21-34%

Nylon 6,6: 24-29%

Polyvinyl Chloride (PVC): 45-49%

Halar (E-CTFE): 64%

Teflon (PTFE): 95%

Nomex: 28%