Compressed Gas
Determining Net Quantity of Gases for Shipping by Air

How much gas can I ship by air per cylinder?

In theory this is an easy question. In practice, it can be easy too, or of course, we can make life difficult on ourselves and do some math.

We’ll start with the easy stuff. Look up the commodity in IATA Section 4.2 (a.k.a. The Blue Pages). We’ll use UN1978, PROPANE, CLASS 2.1 as an example. It is forbidden on passenger aircraft and we find a value of 150 kg as a maximum net per package on Cargo Aircraft Only.

Appendix A defines “Net Quantity” as “the weight or volume of the dangerous goods contained in a package excluding the weight or volume of any packaging material.” This means we are only concerned with the weight of the gas, not including the weight of the cylinder.

So that should be easy right? We just have to weigh the full cylinder and subtract the tare weight of the cylinder (what it weighs without the gas). Yes, that’s pretty much it! Using our example, we weigh our propane tank, subtract the tare weight of the tank and so long as that difference doesn’t exceed 150 kg, we’re in good shape.

One final thing to confirm is that the cylinder doesn’t exceed any maximum quantity that may be limited by the country of manufacture. In Canada, this can be referenced using the CSA Standard B339-08.

Now, any chemist Continue Reading…