A 55-gal drum can hold approximately 4,200 spent aerosol cans. We recommend the drum to be emptied/replaced when it is 70-75% full (approximately 10” from the top). We offer a counter device that records the number of cans that have been punctured. This takes the guess work out of keeping track of the number of cans that have been processed.
https://www.justrite.com/aerosolv-counter-5700-28225


