A GAS MONITORING ARRANGEMENT

A housing contains a diffusion indicator tube provided with a predetermined breaking point and the housing has an upper part and a lower part joined together by a film hinge. To open the inserted diffusion indicator tube its predetermined breaking point is positioned opposite the film hinge. By bending the housing parts, the break-off end breaks off the test tube at the predetermined breaking point, thereby opening the reaction section. The parts of the test tube are removed, and then the reaction section is pushed into the upper part, now with its closed end first, whereupon it is snapped into the lower part. Its opening at the bottom shoulder of the lower part is exposed to the ambient atmosphere which diffuses into it. In the presence of the gas to be monitored there will be discoloration due to reaction. The discoloration can be observed continuously through the open side of the holding means.