ABSTRACT
In the 1960s, development of the first generation of electrochemical oxygen sensors allowed the incorporation of oxygen measurement into real time direct reading portable instruments. The oxide semiconductor sensor used in some survey instruments targeted towards sewer entry applications is so widely responsive that a positive reading is impossible to interpret. Practitioner has the choice of indicator tubes, dosimeters, and portable real-time instruments based on a wide variety of detection principles. Atmospheric hazards associated with enclosed spaces on ships have been another spur to the development of modern atmospheric testing devices. An important consideration for use of monitoring instruments in environments containing high concentrations of oxygen is the testing used to classify or approve the instrument for use in hazardous locations. Testing for oxygen or any other atmospheric hazard that may be present must occur at all vertical levels between the highest and lowest point in the confined space.
