Canisters

Canister refers to a sealed container used to store or transport various substances. Typically cylindrical, but can also be box-shaped, canisters are made from metal, glass, or high-strength plastics and are designed with closures such as screw caps, crimp seals, or valves. They are used to protect contents from moisture, air, light, or contamination and are built to meet pressure or durability requirements as needed.

Common applications include storage of dry foods (coffee, tea, spices), medicinal powders, and other small items where airtight containment preserves flavor, potency, or cleanliness. In science and industry, canisters may be used to hold powders, reagents, or samples during transport or processing.

Pressurized gas canisters are a major category, using lightweight metal vessels to store compressed gases for dispensing, propulsion, or instrumentation. Examples include carbon dioxide cartridges for beverage dispensers, nitrous oxide cartridges for whipped cream, and gas capsules used in paintball markers and air rifles. These vessels require certification and safety labeling because of internal pressure and hazard.

Aerosol and filtration contexts also employ canisters. Aerosol canisters contain spray formulations; canister filters and vacuum units use a detachable container that holds filter media or collects debris, enabling periodic replacement.

Historically, the term canister has been used for canister shot, a form of ammunition in which small projectiles were packed into a single container and fired from cannons to create a lethal shower at close range.