Fogging vs Spraying

Most biologically active chemicals (insecticides, fungicides, disinfectants and deodorizers) will give their best results if applied in small droplets between 10 and 100 microns in size, according to chemical type. However, droplets in this size range are highly susceptible to being drifted long distances by wind. This is why most outdoor (agricultural) spraying is done using droplets of 200 to 400 microns. Where wind drift is advantageous, or in a closed building, smaller droplets can be utilized to maximize the efficacy of the chemical and reduce application costs.

Thermal Fogging

A thermal fogger is appropriately named since it is a device that uses heat to produce a fog without degrading the active ingredient. A thermal fogger produces a range of droplet sizes including a large number of very small droplets. This makes a thermal fogger the preferred type of equipment to reach air spaces in areas highly obstructed by vegetation, or other physical obstructions in buildings. The large number of very small droplets produced in a thermally generated fog also make the fog highly visible. This can help the operator to monitor the fog and ensure thoroughness of application.

Ultra-Low-Volume ( ULV) Cold Fog

A ULV sprayer generates fog droplets by using a high volume of air at low pressure. Such a system enables droplets of a more precise size to be generated. The absence of a large number of very small droplets will limit the penetration of the fog into highly obstructed areas. ULV sprayers can dispense formulations in a more concentrated form since less diluent is required. Also, the ability to be able to calibrate the machine to produce droplets of the optimum size for the type of chemical being used make ULV spraying the method of choice whenever possible.