Helium tanks can be refilled at several different locations, including: Welding supply stores: Many welding supply stores offer helium cylinder refills. Gas companies: Some gas companies offer helium cylinder refills, either at their facilities or through mobile filling services. Party supply stores: Some party supply stores offer helium cylinder refills, especially if they also sell balloons and other party supplies. Balloon distributors: Some balloon distributors offer helium cylinder refills for customers who purchase balloons from them. Online retailers: Some online retailers offer helium cylinder refills and delivery, allowing customers to have their tanks refilled without having to leave their home. It is important to choose a reputable provider for refilling the helium cylinder, to ensure the safety of the cylinder and the quality of the gas. Before having a cylinder refilled, it is also important to make sure the provider is licensed and insured, and to follow any guidelines or regulations for the safe handling and storage of the cylinder.