Are You Foggy About Foggers?

If you have studied the principles of deodorization, you know that the third principle is “to recreate the conditions that caused the contamination with a deodorizing spray, fog, or gas.”

The primary purpose for deodorizing equipment is the application, distribution, spraying, or fogging of a deodorizing agent, solution, or gas directly to a surface or to the general airspace to “recreate” the conditions of penetration by the odorous gas. Odor molecules are measured for their particle size by mass median diameter (MMD). Their MMD is measured in microns. A micron is equal to 1/1,000,000th of a meter. Therefore, in most cases the size of the particulates or droplets produced by deodorizing equipment is measured in microns.

There is a wide variety of deodorizing equipment because the process of deodorization and odor control can be complicated. It is important to consider the importance of combining other methods of deodorization with fogging in deodorization and odor elimination. Relying solely on one deodorization technique, particularly fogging, as the only means of odor control may result in ineffective odor control or incomplete results.

Safety Considerations

When deodorizing air space with any chemical or gas, the area should be free of unprotected personnel. Anytime a chemical is made into a fog, respiratory, skin and eye protection should be used. Any chemical or gas released into the air should be considered a respiratory irritant. No deodorizing chemical should be sprayed or fogged into the air without adequate respiratory, skin, or eye protection for all personnel. Virtually all types of deodorizing equipment may involve some level of toxicity (remember, water is toxic if you are sitting at the bottom of a swimming pool), respiratory irritation or combustion problem if improperly used.

The use of appropriate Personal Protective Equipment (PPE) is required by OSHA at all times during work hours when real or suspected hazards exist. The use of respiratory protection, chemical resistant gloves, and safety goggles is often appropriate and sometimes required when using deodorizing equipment.

Types of Fogging Equipment

The professional cleaning, deodorizing, restoration, or remediation technician has access to several different types of fogging equipment. Fogging equipment is used in several industries other than ours; it is commonly used for the airborne application of pesticides and insecticides. In fact, you may have seen a truck-mounted thermal fogging machine out and about in your town when they are spraying for mosquitoes. Many of the directions included with fogging equipment are primarily written for these types of applications; make sure you understand the directions of the fogging chemical you are using to deodorize in conjunction with the proper operating instructions of the fogger you are using.

In our industry, there are generally two types of foggers used – wet or cold foggers and hot or thermal foggers. Traditionally, wet foggers were employed for the application of a fog or stream of spray of water-based deodorizers into the air. Thermal foggers were employed for the combustion of a petroleum distillate into a deodorizing, “smoke-like” fog. Wet foggers were most often used in the application of decontamination deodorizers or EPA-registered disinfectants or sanitizers on water-damage restoration jobs and in the treatment of air ducts. Thermal foggers were more often used to treat smoke odors in fire damage restoration and with environmental tobacco smoke. Like everything else in our industry, advancements in technology and chemistry and expanded and stretched these traditional applications.

Wet or Cold Foggers

Wet foggers are used to apply light-to-heavy amounts of water-based deodorizing treatments. Care should be taken to protect moisture-sensitive surfaces and avoid overspray in the area being treated. When using wet foggers, in most instances the use of respiratory protection is recommended, as aerosolized solutions may serve as a respiratory irritant. There are three types of wet or cold foggers generally available in our industry: tri-jet, ultra-low-volume and air blast atomizers.

A tri-jet is a three-jet fogger specified primarily for use in the application of water-based deodorants into deodorant particles from 20 to 50 microns. Tri-jet foggers are not as common in our industry as they once were, primarily because their large droplet size meant that more precautions needed to be taken to protect moisture-sensitive surfaces and furnishings. Tri-jet foggers would traditionally have been used for a quick application of a deodorizing fog for general purpose deodorization.

Ultra-low-volume foggers are specified primarily for use in the application of water-based deodorants into small deodorant particles from 8 to 15 microns. As compared to a tri-jet fogger, the ULV fogger allows for a reduced concern about moisture-sensitive surfaces due to the much smaller droplet size. The two primary types include single snout type and gooseneck extension type. The single snout type has the fog being produced from the front of the unit. Gooseneck extension modules have a gooseneck hose that allows the fog to be directed into particular areas, and a diffuser at the end of the hose to keep the fog in suspension. Ultra-low-volume foggers are generally the wet fogger of choice for the professional technician today. They are used in water-damage restoration, and can be used to deodorize airspace affected by skunk musk odors; tear gas; mold and fungi odors; “stale” air; environmental tobacco smoke odors; decomposing protein odors and fuel oil spill odors.

An air blast atomizer is designed to direct primarily water-based deodorants into a particle fog for application into inaccessible areas. The particle size ranges from 50 to 200 microns. The air blast atomizer shoots a stream of fog up to 30 feet. It is often used to shoot a deodorizing chemical treatment into inaccessible areas such as crawl spaces and attics. Sometimes, when the carcass of a decomposing animal is located in a tight space where removal is too costly, the ability to saturate spray and fog a chemical treatment into the area is crucial.

Hot or Thermal Foggers

These units are utilized by applying heat to solvent based deodorizers (petroleum and food grade oil) into a smoke-like fog, producing particles as small as 0.5 to 2 microns. These units reproduce or re-create the energy, heat, and pressure of smoke and fire. This allows a deodorizing fog to penetrate all the porous surfaces the smoke did. Thermal fog can be directed into tight and inaccessible areas where it is impossible or impractical for the restoration technician to go. They are ideal for the deodorizing of large areas, fabric, and hard porous surfaces. Care should be taken during the application of thermal fogging solution.

Traditionally, thermal fogging chemicals were only petroleum-based. One chemical manufacturer recently developed a thermal fogging chemical containing only food- and cosmetic-based ingredients. This allows you to detoxify contaminated environments without adding unnecessary volatile organic compounds.

Thermal fogging is most often used in treating smoke odor simply because it looks like and acts like smoke, allowing it to travel and penetrate to wherever the smoke traveled and penetrated. However, due to the incredibly small particle size of the fog, thermal fogging can be used to deodorize odors that have penetrated into any hard, porous surface. If you have lingering odors in an area even after initial cleaning and deodorizing procedures, and all of the contamination that caused the odor has been removed, then thermal fogging may be considered as the next step.

Due to the nature of thermal fogging and the fact you are creating a combustion process; several precautions must be considered before application of a thermal fog:
  • The over-application of the solvent fog can leave an oily residue.
  • The solvent is transformed into a fog by the application of combustion. This combustion creates an intense heat, and in the case of some thermal fogging units, an open flame.
  • Deactivate fire suppression systems, particularly sprinkler systems, before thermal fogging. Prior to thermal fogging a facility or home, you should notify the local fire-fighting authorities.
  • Since you are combusting a solvent material, care should be taken to prevent secondary combustion. Extinguish all open flames (pilot lights, etc.). Failure to do this may result in an explosion. This is the most serious safety hazard related to thermal fogging.
  • Thermal fog is a respiratory irritant. The area being fogged must be free of unprotected personnel. Remove all pets prior to thermal fogging. The technicians should wear appropriate respiratory protection.

The different types of thermal foggers include:
  • Propane. A “camping” propane cylinder is used to create the heat. This unit takes special precautions because it produces an open flame. It was designed for outdoor use only.
  • Electric (Small Handheld). Combustion takes place within the heating chamber making this unit easier to use. Ideal for confined areas or “touch-up” fogging.
  • Gasoline powered (Large Units). These are used for rapid fog production and resulting odor reduction throughout a building. Because of their smaller particle size (0.5 micron), they are better for wood and clothing.

Vapor Diffusers

A relatively new type of deodorizing equipment that can often be used as an alternative to fogging or the use of ozone gas is vapor diffusers. While not really a fogger, because the do not break down a water- or solvent-based deodorizer into a droplet fog, these odor-control systems are still primarily designed to deliver proprietary odor-control solutions throughout the airspace. Treated membranes or disks are impregnated with essential oil and odor-control compounds. Through convection, these electric- or battery-powered units breathe a penetrating dry vapor wherever the air circulates. While these units were designed to offer an alternative to fogging or ozone treatment in smoke-odor environments, their application and usefulness can be extended to all sorts of odor problems. The deodorizing vapor created by a vapor diffuser acts similarly to fog, in that the vapor can travel throughout a structure into all sorts of difficult to access areas and voids.

Hopefully this helps clear up the fog in your head about the different types of fogging equipment you have access to. Whether you are a carpet cleaner simply trying to help a homeowner deal with a lingering odor problem, or a restoration or remediation company dealing with a building wide odor disaster, you will eventually find yourself in need of fogging equipment. Fortunately, today you have access to all of these types of equipment, with models and instructions and procedures designed specifically for our industry. To learn more about fogging equipment, I recommend you attend a specialized odor-control or smoke-damage class at your local distributor.

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