Evaporative Emissions Control

Did you know that more than just water can evaporate? As long as the object is in liquid form then there is the distinct possibility that it can evaporate if the right degree of heat energy is present, enabling an energy transfer significant enough to cause the escape of molecules from the main volume. That’s one reason why evaporative emissions control has continued to be a significant issue across dozens of different industries.

Some of the harmful evaporation emissions to escape automobiles are hydrocarbons. These are produced from automobiles by the natural vaporization of gasoline and from the crankcase of the automobile. These types of auto emissions have a horrible cumulative effect and that is why have seen some excellent legislature being put in place to help curb this, such as the clean air act of 1977. This act limits the amount of each of specific pollutant produced by an automobile.

This venture to drastically reduce these harmful evaporative emissions has also led to the designing of specialized computers within automobiles as way to control emissions. These computers enable the engine to actually adjust itself. This helps the engine perform at the most efficient levels possible which helps to significantly reduce the quantity of each pollutant emitted into the atmosphere. This most certainly is an amazing step forward since previous to legislature put in place in 1970, the direct venting of gasoline evaporate emissions was actually common place for most auto designs.

The reason venting was such a big issue is because gasoline actually evaporates very easily. If direct atmospheric venting were still allowed then our current pollution levels would be even more dangerous than they already are.

Some of the first evaporative emission control designs arrived around 1981, enabling engines to maintain self adjusting operation. These were commonly referred to as feedback fuel control systems. These systems feature an oxygen sensor that is positioned within the exhaust system. This inclusion of the sensor in the exhaust system allowed it to measure the exhaust’s contents, relaying a corresponding signal to a microprocessor. This device would then take a reading of the contents and send appropriate directions on to the fuel mixture or air mixture device to create the right air to fuel ratio.

While oxygen sensors still play a role in the design of today’s automobiles, evaporative control systems have evolved to eliminate the source of pollution and essentially trap and store evaporative emissions.