Compared with other nozzles, the structure of two fluid spray nozzles is more complicated. There are 2 flow tunnels for gas and liquid inside the nozzle. Due to air and liquid tightness requirements, two fluid spray nozzles are usually designed with multiple pieces. This complexity makes its manufacturing more expensive.
● Two-Fluid Spray Nozzles: Principles and Advantages of High-Velocity Aerodynamics
The basic principle of two fluid spray nozzles is that the liquid is crushed by the gas with very high velocity which causes the liquid to be sprayed out in a very small particle size. Chemicals sprayed out through two fluid spray nozzles are with smaller particle size and a larger contacting area for faster and more efficient reaction with less chemical waste. Relatively speaking, if adopting another kind of nozzle for the same circumstances, the particle size sprayed from it is much larger which makes part of chemicals remain on the chemicals already reached the surface instead of contacting the surface which leads part of chemicals unable to take reaction. As a result, using two fluid spray nozzles makes half or one third of the chemical consumption of other kinds of nozzles.
● Two-Fluid Spray Nozzles: Chemical Usage and Environmental Impact
In addition, inside the two fluid spray nozzles, gas and liquid are fully mixed. If the liquid contains chemicals, it will cause the oxidation reaction with the air which causes the chemicals to have a steeper natural decline curve. It means the decline speed of the chemicals will be faster than usual and shorten its sustainability. As a result, it will make a higher amount of chemical usage. Users have to consider the amount of chemical usage while thinking about adopting two fluid spray nozzles.
After the liquid was crushed by the gas, its particles became very small. The flowing gas will bring relatively smaller particles away which means part of chemicals will be away with waste gas and leads to more chemical consumption and pollutes the waste gas to be harmful which needs to be treated additionally.
● Two-Fluid Spray Nozzles: Balancing Chemical Efficiency and Consumption
Moreover, as previously mentioned, when using the two fluid spray nozzles, the chemical is possibly taken away by dissipated gas. However, the sprayed chemicals with smaller particles enlarge the contacting surface which makes a faster chemical reaction.
Higher chemical consumption caused by its being brought away by dissipated gas could offset partly the highly efficient chemical reaction caused by larger contacting surfaces. Therefore, when using the two fluid spray nozzles, the actual chemical consumption has to be considered by the users’ experience. Users are highly recommended to stay on-site for continuously watching the chemical consumption.
● The difference between internal and external crush and mix for 2 different type of two fluid spray nozzles
➤ Internal mix：
Gas crushes and mixes with liquid inside the nozzle.
Disadvantage： Crystals will be generated by the liquid being dried inside the nozzle which may cause the nozzle to be clogged.
Advantage： It lessens the gas consumption which decreases the cost due to the very high cost of high pressure.
➤ External mix：
Gas crushes and mixes with liquid at the sprout of the nozzle. After, it becomes a dissipated mist and small particle spray to the surface.
Disadvantage： Sprayed gas might be partly dissipated. There is only part of gas left for crushing and mixing liquid which leads to more gas consumption and increases the cost.
Advantage： No clogging.