49 CFR § 173.192 - Packaging for certain toxic gases in Hazard Zone A.
When § 172.101 of this subchapter specifies a toxic material must be packaged under this section, only the following cylinders are authorized:
(a) Specification 3A1800, 3AA1800, 3AL1800, 3E1800, or seamless UN cylinders with a minimum test pressure in accordance with P200 of the UN Recommendations (IBR, see § 171.7 of this subchapter).
(1) Specification 3A, 3AA, or 3AL cylinders may not exceed 57 kg (125 lb) water capacity (nominal).
(2) Specification 3AL cylinders may only be offered for transportation or transported by highway and rail.
(b) Packagings must conform to the requirements of § 173.40.
(c) For cylinders used for phosgene:
(1) The filling density may not exceed 125 percent;
(2) A cylinder may not contain more than 68 kg (150 lb) of phosgene; and
(3) Each cylinder containing phosgene must be tested for leakage before it is offered for transportation or transported and must show no leakage. The leakage test must consist of immersing the cylinder and valve, without the protective cap attached, in a bath of water at a temperature of approximately 66 °C (150 °F) for at least 30 minutes, during which time frequent examinations must be made to note any escape of gas. The valve of the cylinder may not be loosened after this test. Suitable safeguards must be provided to protect personnel and facilities should failure occur during the test. As an alternative, each cylinder containing phosgene may be tested for leakage by a method approved in writing by the Associate Administrator.