This ARP covers a procedure to be used in the determination of 0.05 to 0.3 ppm of chlorine in oxygen from any type of generator used for emergency or life-support systems. The methyl orange method described can be considered as a referee technique. Purpose: This ARP describes a method for rapid and reliable measurement of chlorine in oxygen from a solid chemical oxygen generator. The method of sampling and analysis used in this procedure is adequate to encompass the range of interest relevant to the 0.3 ppm limit set for chlorine in oxygen. The test is sufficiently flexible to make the determination during a part of or for the first 60 s after activation@ since this is the usual time during which chlorine may be found in the oxygen being generated.