The Plain Man's Guide to Aerosols

AEROSOL CANS


Metal aerosol cans are usually made from tinplated steel, or aluminium.

Tinplate aerosol cans are mostly made up of three components - a top containing the valve opening, a body and a bottom.  Some two piece cans are also now available.  Aluminium cans are usually made from single piece of aluminium metal.

The tinplate used to make aerosol cans is low carbon mild steel sheet, coated with tin applied by electrodeposition.  The thickness of the tinplate sheet used to make aerosol cans will vary, depending on the size of the can, the pressure specification, and whether it is for can bodies or end components.  For can bodies the thickness will range from 0.18mm to 0.25mm, and for tops / bottoms they will be 0.28mm to 0.43mm.

Unless otherwise specified, the layer of tin on the steel is the same thickness on both sides.  Again the amount of tin will vary, ranging between 2.0 g/m² and 2.8g/m².  The internal surfaces of the tinplate will be either uncoated, or have a lacquer, or other material applied to give the metal better corrosion resistance.

Tinplate combines the strength and formability of steel together with the corrosion resistance and good appearance of tin.  Tin is a very soft metal and because the tin coating is very adherent it follows the movement of the steel base when tinplate is formed into the various components of an aerosol container.

Aerosol containers must be capable of withstanding the internal pressures generated during filling, and the subsequent transport, warehousing, and usage in the consumer's hands.  They must also safely contain the product throughout the life of the aerosol.

Aerosols are pressurised systems, and as such they are governed by legislation.  This not only covers the manufacture of the empty can, but also its subsequent filling.

Legislation governs the amount of product that may be filled into aerosol cans, and for safety reasons there will always be some space in the can which does not contain liquid.  If you shake a 'full' aerosol you will usually hear the liquid moving around, due to the head space in the can.  Because an aerosol is under pressure there must be sufficient space for the propellant to occupy, under all likely conditions.  The amount of head space is greater when a compressed gas, such as air, is used, as these propellants operate at higher pressures than those for liquified propellants.

 


RELEVANT STANDARDS

British Standard BS 7289 : 1990 Specification for dimensions of three-piece tinplate aerosol cans.

FEA¹ Aerosol Standards, FEA, Brussels, 1993: Including;

FEA 214 Metal Aerosol Containers - Dimensions of three piece tinplate cans.

FEA 220 Metal Aerosol Containers - Dimensions of one piece aluminium cans with 25.4mm opening.

FEA 202 Metal Aerosol Containers - Dimensions for valve cups suitable for 25.4 mm aperture containers.

(¹ Federation of European Aerosol Associations)

European Standard EN 10203 : 1991 Specification for Cold reduced electrolytic tinplate

British Standard BS 3914 : 1991 Non-refillable metal aerosol dispensers of 50mL to 1400mL capacity and up to 85mm diameter

European Standard EN 10202 : 1990 British Standard Specification for; Cold reduced electrolytic chromium/chromium oxide coated steel.

Council Directive 75/324/EEC of 20 May 1975, on the approximation of the laws of the Member States relating to aerosol dispensers.

Commission Directive 94/1/EC of 6 January 1994, adapting some technicalities of Council Directive 75/324/EEC on the approximation of the laws of the relating Member States relating to aerosol dispensers.

Statutory Instrument 1996 No. 2421 Consumer Protection; The Aerosol Dispensers (EEC Requirements) (Amendment) Regulations 1996.

Prescribed Quantities Directive 80/232/EEC


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Last revision : 1 January, 2007