High Pressure Fogging – Another way to keep cool

high pressure fogging systemsWhen we talk about evaporative cooling, most people think first of cool pad systems. Today, however, we want to highlight the less well known but more versatile evaporative cooling that comes from fogging systems.

First to clear up a little confusion of terms: Fogging, misting, and sprinklers. Some people use them interchangeably but there is a difference. Fogging systems differ from misting or sprinklers in that they produce a much smaller droplet. Sprinklers operate at mains pressure (about 20-65 psi, typically) and put out a drop of water up to 1/16” diameter (2mm). Misting systems may run at 80-200 psi and put out a smaller droplet, around 100 microns – about the thickness of a human hair. Fogging systems operating at 700-1000 psi produce droplets around 25 microns – as fine as the point of a needle. The smaller the droplet the more quickly it can evaporate. The faster it can evaporate the less likely it is to wet the floor, litter, or equipment.

Next understand that the same principle operates in fogging (or misting or sprinkling) as in a cool pad – water is evaporated into the air – lowering the air temperature while increasing the relative humidity (Rh). So for every 2.5% increase in Rh through fogging, we can decrease the temperature about 1°F (0.5°C).

So what makes fogging different from cool pads – what are the reasons for or against using it?



Is one “better” than the other?   It all depends on the application and personnel involved. Are you retrofitting an existing barn or building new? Fogging installs easily in retrofits but it is likewise easy to frame out cool pads in a new building project. Is all the air brought in through the ceiling? Cool pads could be a significant investment here. What is the average outside temperature? It may be too hot early on in a growout but too soon for significant airspeed – fogging would be an ideal way to cool young animals, but in cooler climes unnecessary. And why not do both? If you already have cool pads but the temp rises more than 5°F from the inlet end to the fan end add fogging halfway down the house to boost the cooling and maintain a more even temperature.

If you want to know more about airspeed, click here.

Want a deeper dive into cool pads? Click here.

Want a quote on best evaporative cooling for your application? Click here.


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