Significant Uses Of Fluids In The Form Of A Spray

By Haywood Hunter


While the general meaning of the word spray is widely known, most would struggle to give a more definitive explanation of the term. To illustrate what it really means, we can look at the spray that is produced when a deodorant can is used. The deodorant itself is stored as a liquid in the container, and emerges into the air as a mist. This familiar example ties in perfectly with how a spray is defined as drops of liquid distributed in a gas.

In the above example, the air was the gas that that the drops of deodorant were dispersed in. However, the definition of a spray allows for liquid to be sprayed into any gas, for example when various liquids are sprayed into the emissions of power plants, to help strip out harmful chemicals.

The process of creating a spray is sometimes called atomization. In practice, the liquids are not literally split down into individual atoms, but rather, small liquid droplets. The significance of changing liquids into this state can be seen by looking at some examples of how sprays are used. Since liquid sprays are used in so many applications, only a selection will be considered.

Sprays are used extensively by companies producing foods and drinks. Spray washers are used to clean fruit and vegetables, while many flavorings and additives are sprayed onto foods. Sprays are very controllable, which helps manufacturers to ensure the correct amount of ingredient is added, for example a little too much spice will make food inedible for some people, so reasonable precision is required. Another advantage of sprays is that they can help ensure a uniform distribution of ingredient is applied over a food product.

Another huge application for sprays within the food and drinks industry involves the process of spray drying. This is the technique used for creating such ubiquitous products as instant coffee, powdered milk, spices, colorings and many others. Because spraying turns a liquid into many tiny particles, these can be dried very quickly in warm air.

A more common and well recognized use of sprays is that of spray painting, although there are more refined examples of this than the simple can of spray paint that immediately comes to mind. Whatever product has to be painted can be made to literally attract the paint, by using electrical charges. The product and the paint are charged oppositely, and this is called electrostatic spray painting. Using this technique can be advantageous where paint has to be applied into tight spots which a paintbrush cannot reach.

Arguably one of the most significant of all uses of sprays is the way they are utilized in engines. In many engines, the fuel is turned into a spray directly before it is ignited, creating tiny, easily ignited drops of fuel mixed evenly with air, a very desirable combination. This principle is widely applied in jet, diesel, rocket and petrol engines, as well as in steam boilers.

As can be seen, the familiar but poorly understood concept of the spray touches our lives in numerous and powerful ways, whether that is in the power stations that heat our homes, the food we eat, common products like deodorants and spray paint, or the vehicles that make our world run.




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