Droplet Size Basics
The spray pattern of a nozzle is made up of many droplets of varying sizes. Droplet size is the diameter of an individual spray droplet and measured in microns (micrometers) often notated with the symbol µ. One micron equals 0.001 mm(0.0000394"); there are 25,400 microns in one inch. For example, the diameter of a human hair is about 100 microns.
Most nozzles have a wide array of droplet sizes. These droplet sizes are commonly summarized by statistical analysis based on testing from sophisticated droplet size measuring equipment.
Remember, droplet size can vary based on pressure. The same nozzle can produce medium droplets at low pressures and fine droplets at higher pressures. Pressure is the direct factor.
The factors affecting the droplet size in the spray mainly include the properties of the liquid, equipment parameters, and operating conditions.
Spray Medium:
Liquid Properties
1.Viscosity:
The higher viscosity, the greater the internal resistance, and the more difficult it is for the droplet to break, resulting in an increase in droplet diameter.
2.Surface Tension:
The greater the surface tension, the stronger the ability of the liquid to maintain a spherical shape, and theplet diameter increases accordingly, but the impact is relatively small.
3.Density:
The higher the density the liquid, the greater the inertial force, and the easier it is for the liquid to break, reducing the droplet diameter.
Nozzle Parameters:
1.Nozzle Type:
For example, the the frequency of the ultrasonic atomizer, the smaller the droplet size and the more uniform the distribution; increasing the jet pressure of the pressure nozzle can reduce the dro size.
2.Nozzle Hole:
As the diameter increases, the initial diameter of the jetens, and the droplet size formed after fragmentation is larger.
3.Nozzle Structure:
Parameters such centrifugal, straight spray, etc., also affect the droplet size.
Operating Conditions
1.Spray Pressure/Velocity:
As the pressure or velocity increases, the liquid's kinetic energy enhanced, the turbulence intensifies, and the droplet fragmentation is more complete, reducing the size. However, too high a flow rate may lead to uneven atomization or energy waste.
2.Flow Rate:
When the air atomizing nozzle is working, reducing the gas flow rate and the working liquid flow rate can control the bubble size within a smaller range.
3.Environmental Factors:
Operating environment, such as installation height, wind speed, etc., may also affect the atomization effect.
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