Overview
Sizes
Compressed gas cylinders of all four types (i.e. compressed, liquified, refrigerated, and dissolved) come in different sizes. The image shows the range for compressed gases. The letter on each cylinder shown in the image following is the common term used to describe the size of the cylinder. For large compressed gas cylinders in labs, the most common size is ‘K’. Some manufacturers may have a different naming scheme for their cylinders, but the sizes and volumes are similar to those shown here.
Some of the cylinders in the image are equipped with threads and are capped as shown. Other cylinders, the smaller ones, do not have caps and the cylinder is not threaded for them. If a cylinder needs to be capped when not in use, it will be threaded for it.
There are other types of cylinders that will be discussed later that have different methods of protecting the valve.