|The valve has a number of components: |
A plastic stem with a hole in it. The product passes out through this hole when the valve is opened. The valve is kept closed by a . . .
rubber gasket that slips over the stem. When closed, this seals the hole in the stem. But it can bend downwards to reveal the hole (see next paragraph). The stem and the rubber ring sit in a . . .
housing. When the actuator is pushed down, the ring is bent downwards and uncovers the hole - letting the product through. Inside, there is a spring that pushes the stem back up when the actuator is released; the rubber ring then re-seals the hole in the stem.
The valve design has a big impact on the aerosol spray. Changing the size of the hole in the stem can alter the flow rate. Along with the size and shape of the nozzle, the flow rate will affect the spread of the spray.
The dip tube. The dip tube goes down almost to the bottom of the can to make sure it is always dipped in the product and that you always get all of the product out.