（Question on the application of State Variation USG-18 on UN 3356 Oxygen generator, chemical.）
Please give us guidance on the application of State Variation USG-18 for a shipment of UN 3356 Oxygen generator, chemical. Is it correct to understand that US Governmental classification and approval are not needed for UN 3356 shipped on a freighter? USG-18 refers to "UN 3356 that is transported with a means of initiation attached must be classed and approved by the US Government". Does this mean an approval is needed from the US Government? What does "must be classed" mean? If there is no initiation device, and carried by a freighter and the quantity is 25kg or less, and the packaging satisfies IATA standards, no further approval is required from the US Giverment? (30 Apr 17)
When shipping UN 3356 Oxygen generator, chemical (refer 49CFR 171.8 for definition) by a freighter (CAO), the provisions of 49CFR 173.168 must be satisfied. The contents of 49CFR 173.168 is generally identical to the provisions of DGR SP A1, A111, A116, A144 and PI 565.
Regarding Chemical Oxygen Generators having an initiation device, since it involves explosives, classification and approval by a competent authority of the US Government (DOT, FAA) is mandatory based on the provisions of 49CFR 173.56. For details, please refer to 49CFR.
When without the initiation device, and the load is less that 25kg, and loaded on a CAO aircraft, and the provisions of 49CFR 173.168 is met, no further approval is needed.