Passive dositubes are used to measure time-waited average (TWA) gas concentrations over longer periods. Dositubes use the principle of the natural diffusion of gas.

A dositube is a glass tube of a specific inner diameter that is filled with a diffuser and chemical reagent in parallel that enable gas to disperse at a constant rate resulting in a longer discolouration and better demarcation. The passive dositube can then be positioned in the worker's breathing zone where it can be attached with a holder and collar clip and the amount of individual exposure can be measured.

Stationary use is also possible for TWA measurements of concentration distribution or change within a fixed environment over longer periods, such as the course of a whole day.

Features

• Compact, lightweight, and versatile
  (can be used anywhere)
• Easy direct measuring and reading
• No sampling pump necessary