Circular-shaped pressure containers, cylinders are used to store high-pressure and liquefied gases. Generally cylinders with a more “squared off shoulder” appearance are lower in pressure while cylinders with a more “bullet” shape appearance are higher pressures. With a few exceptions, most cylinders are required to have pressure relief devices in the event of over pressurization due to over filling or over heating.

The Compressed Gas Association (CGA) has recommendations for color-coding of cylinders based on their contents, but there is no mandatory regulation specifying color-coding by content. Be careful not to make assumptions of contents based on colors as they can change by vendor or supplier.