Refrigerant containers
There must be pressure space available in the fluid area of the container. At increasing temperatures the fluid expands, the space filled with vapor becoming smaller. At a specific point there will only be fluid in the container. Beyond this point, only a slight increase in temperature will result in a very high pressure in the container.
Without sufficient room for expansion of R-134a (gas cushion), the container could explode when the temperature rises causing serious injury.
DO NOT exceed maximum rated capacity of refrigerant containers. Never fill a container to more than 60% of its gross weight rating (for example, 18 lb in a 30 lb container.)