Make sure the cylinder is turned off and fully depressurized
Wear appropriate protective gloves and eye protection
Check the cylinder type and cap design
Hold the cylinder steady on a flat surface
Turn the cap counterclockwise if it is threaded
Lift the cap straight up if it is a slip-on type
Use the correct wrench or tool if the cap is tight
Do not force the cap if it resists
Inspect for damage, corrosion, or leaks before continuing
Store the cap safely after removal