Aromatic isocyanate detector - TDI or MDI gas monitor

An aromatic isocyanate detector (more commonly known as a TDI detector or MDI detector) is used to measure concentrations of these gases in the manufacture of flexible and rigid foams for insulation or padding. TDI (Toluene Diisocyanate) and MDI (Diphenylmethane 4,4'-Diisocyanate) have been the most widely used aromatic isocyanates for many years.

Exposure to aromatic isocyanates is dangerous to health even at very low thresholds (of the order of ppb) which can lead to lesions of the respiratory mucous membranes, skin and eyes irritation, asthma, eczema, conjunctivitis, etc. where the need to monitor concentrations of these gases very regularly with very precise isocyanate gas detectors.

There are few TDI gas detectors or MDI gas monitors on the market. SafeAir chemical detection badges are the easiest and most often used (as a portable detector), they are equipped with a flat sensor that changes color when exposed to toxic gas. There is also the SPM FLEX (portable or fixed version) with its high performance colorimetric reagent paper technology and a linear 4-20 mA output.