Lesson 1/learning Event 2
Learning Event 2:
DESCRIBE THE PRINCIPLES AND OPERATION OF CARBURETORS
Liquid fuel is sent from the fuel tank to the carburetor. To burn properly, the gasoline must be thoroughly
mixed with air. To do this, the gasoline must be vaporized.
When any liquid changes to a vapor, it evaporates in the air. Boiling water is an example of vaporization.
As the water boils, it steams. Steam is made up of liquid in very small particles. These tiny particles (vapor)
mix with the surrounding air.
Several things determine how easily a liquid will vaporize. The nature of the liquid itself is one factor. For
instance, it is a well-known fact that alcohol, which is lighter than water, vaporizes more easily than water.
Gasoline, which is also lighter than water, vaporizes more easily than water.
A second factor controlling vaporization is the temperature. Higher temperatures cause liquids to vaporize
faster. An example of this is water turning to steam when it is boiled.
Another factor controlling vaporization is the amount of vaporized liquid already in the air (humidity). You
can understand this by thinking of the air as a sponge. When a dry sponge is placed in a pan of water, it
soaks up (absorbs) a large amount of water very rapidly. But as the sponge begins to get full, it absorbs
water more slowly. Finally, it reaches a point where it will not absorb any more water at all. Air acts in the
same manner. When you hear the weatherman say that the humidity is 100 percent, this means the air has
soaked up all the moisture it can hold at that temperature.