Other details consist of a solid carrier material impregnated with info pdf 44 kb h sensing chemicals sealed in a glass tube with tapered tips. When a fixed volume of sample air containing the target gas is pulled through the tube by means of a uniphos precision air a discolored, Sampling pump stain develops. Stain length is calibrated to directly read the target amount of gas found percentage or, In ppm mg / m 3 on the tube scale. Tubes are offered for nh 3, H 2 s, So 2, Cl 2, Ph 3, Hcl, Hcn, Co, Co 2, Cs 2, C 6 h 6