a. the cylinders must be in place and properly fastened. Only one protective cylinder valve cap may be removed at any one time, should this be necessary for alignment purposes; b. installation of the carbon dioxide piping must be completed; c. other work in the carbon dioxide room must be completed; d. installation of the release cabinet with valves and locking facilities must be completed, e. the door to the carbon dioxide room must be fitted with a lock; f. the main valves’ ‘open’ and ‘closed’ position indicators must be checked by the work supervisor; g. the main valves must be set to the ‘closed’ position and locked.