There are a great many applications that require a spray (as opposed to a stream) of liquid. Certain droplet sizes, and flow rates, are beneficial for certain applications. For example, if you’re fighting a fire, you want as high of a flow rate as possible – the more water you douse the fire with, the quicker it goes out. You also want a fairly large droplet size, since a mist would tend to evaporate instead of extinguishing the flames.
Pressure washers also benefit from higher (though not near as high as fire hose) flow rates, and droplet sizes. You want an appreciable flow rate, because that means high velocity, and good sized droplets combine that velocity with their relative mass to “blast” away dirt and detritus from the surface.
Medicine delivery devices, like asthma inhalers, are designed to produce mid-sized droplets, but pretty low (and controlled) flows. The droplets need to be small enough to efficiently spread the medicine through the breathing passages, but large enough to where they won’t evaporate before they ‘plant’ on the nasal & bronchial membranes to get absorbed.
These are examples of “liquid-only” nozzles…no other media or means of force are used to effect the spraying action. Most of the time, the droplet sizes in these applications are measured in hundreds of microns, which “liquid-only” nozzles are ideally suited to generate. Other applications, however, call for much smaller droplet sizes…such as those only attainable through atomization.
EXAIR Atomizing Spray Nozzles use compressed air to create a fine mist of liquid, with droplet sizes as low as 22 microns.
Small droplet size is key to cost effectiveness in many applications:
- Think about expensive coatings…the smaller the droplet size, the better and more even the coverage, and the less you have to spray (and pay) out.
- Or humidification…smaller droplet size means more stays airborne, for longer, and in a larger space.
- Petroleum based lubricants, by their nature, only require a thin layer for best results. Smaller droplets make as even and thin of a layer as possible.
- Dust control is much more effective with smaller droplet sizes, since the longer the mist lingers in the air, the more dust particles the individual droplets will adhere to…and then drop with them to the surface. This also prevents getting the surface of the material any wetter than it has to be.
If you’d like to discuss a liquid spraying application, I’d love to hear from you. Call me.
Russ Bowman
Application Engineer
EXAIR Corporation
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