Isocyanate detector is used for measuring vapor and aerosol levels of isocyanate compounds such as MDI, TDI, or HDI. It is housed in an environmentally sealed tamper resistant enclosure with an eternal membrane switch control panel. It operates on DC current from an external power supply and has internal battery backup. A large LCD on the detector indicates gas concentration and features a visual alarm that is triggered when a preset alarm level is exceeded. The LCD also shows self-diagnostic data such as unit readiness, alarm set level, battery current and charge voltage, percent of sampling tape remaining and fault situations.

Isokinetic sampling is the term used for sampling at the same flow velocity as the test atmosphere. The sampling probe used for isokinetic sampling is a thin walled tube aligned so that the air flows directly into it. The streamlines of the flowing air will be bent either away from the opening, if the linear speed of the sample in the probe is slower than in the duct, or into the opening if it is faster.