Guide to Aerosols
A typical Aerosol Valve is made up from several components:
• Valve Cup :- typically constructed from tinplated steel, or aluminium.
• Outer Gasket :- this is the seal between the valve cup and the aerosol can.
• Valve Housing :- contains the valve stem, spring and inner gasket.
• Valve Stem :- in effect, the tap through which the product flows.
• Inner Gasket :- covers the hole in the valve stem.
• Valve Spring :- usually stainless steel.
• Dip Tube :- allows the liquid to enter the valve.
• Actuator (not shown) :- fits onto the valve stem.
The valve is supplied already constructed, and the actuator may also be fitted. The valve stem is fitted with a small hole, through which the product flows. Some valves may contain two, or even four holes, depending on the nature of the product to be dispensed. The holes are very small, with diameters as low as 0.30mm, and as high as 1.00mm. In the closed position the hole(s) is covered by the inner gasket.
When the actuator is depressed it pushes the valve stem through the inner gasket, and the hole(s) is uncovered, allowing liquid to pass through the valve and into the actuator.
The valve and actuator are important components in an aerosol, they both contain small holes and channels (not all shown in these diagrams) which control the flow rate through the valve, and the characteristics of the spray which emerges from the actuator.
The valve shown in the diagram is the most common type used. There are other types available, but they are not discussed here.