Gas detector pump that is independent of external energy sources and therefore there are no usage restrictions in areas of explosive hazards. Dräger tubes are the most widely used form of spot measurement in industry. More than 500 substances can be detected and measured using the system. Typical applications include: COSHH monitoring, emission measurements, quality control, process control, compressed breathing air testing, as well as environmental and emergency response monitoring. Gas is drawn into the tube using the Accuro bellows pump where it reacts with chemical on a carrier material. In the presence of the target gas a color change occurs and the length of that discoloration is proportional to the concentration. The concentration can be determined from the calibrated printed scale on the outside of the tube.