C.R.S. § 8-20-304

Sections 8-20-301 to 8-20-303 shall not apply to any gas or gaseous compound referred to in section 8-20-301 , contained in such containers, unless the title to the containers is retained by the owner or his representative, and unless the gas or gaseous substance contained in the containers is sold and delivered upon the understanding and agreement that the container in which it was delivered shall be returned to the owner or its representative when the contents have been used up by the purchaser.