1.1 ,This practice covers the detection and measurement of concentrations of toxic gases or vapors using detector tubes (1, 2).2 A list of some of the gases and vapors that can be detected by this practice, their 1994–,95 TLV values recommended by the ACGIH, and their measurement ranges are provided in Annex A1. This list is given as a guide and should be considered neither absolute nor complete.