1.1 ,This practice covers the detection of hydrogen sulfide gas by visual chemical detectors. Included under visual chemical detectors are: short-term detector tubes (1),2 long-term detector tubes (2), and length-of-stain dosimeters (3). Diffusion tubes are not included under this practice because they are not direct reading, and spot tests are not included because of their poor accuracy. The sample results are immediately available by visual observation, thus no analytical equipment is needed.