Applications of heat: VOCs and Formaldehyde
by Tommy Underhill
January 24, 2019
Thermal pest eradication is a great application for formaldehyde and other VOCs and/or odors. Formaldehyde is a relatively easy chemical to offgass depending on what types of materials the formaldehyde is found. For example, formaldehyde can be found in pressboard or MDF that is located below a granite countertop will have some difficulty offgassing because it needs to travel to a surface adjacent to air. The granite may block much of the route for the offgassing, or may limit the area it can offgas from to just the ends of the pressboard, or a small area. On the other hand, formaldehydes in new furniture will offgas much more readily.
How rapidly VOCs will offgas is dependent on a couple of factors. Offgassing occurs much the same as evaporation. When a material is wet evaporation occurs when the vapor pressure of the wetted material increases causing the moisture to turn into a vapor and move to the air. All of this takes place at the surface of the wetted material. So, to dry a material, the moisture must continually move to the surface and evaporate until the moisture content in the material reaches an acceptable equilibrium. With chemicals this same process occurs. So, a material such as MDF will need to have the vapor pressure increased and the chemicals become vapors and move to an edge of the material. At the edge the offgassing is assisted by air movement, again similar to evaporation of moisture. The material continues to move vapor and as it offgasses it also attempts to reach an equilibrium. This process will occur naturally for long periods of time. Depending upon the material it could be years.
All chemicals have different vapor pressures, so the rate at which they will offgas varies. It also varies dependent on the material they reside. Chemicals that are close to the surface will offgas more quickly than chemicals in the center of a material. I mentioned MDF, if the MDF is located in kitchen cabinetry and the cabinets are covered by granite or similar, the offgassing will take place very slowly. Composite materials that might be used in some flooring will offgas slowly. Materials such as paints or other coverings will offgas more rapidly as they are closer to the surface.
My suggestions are to set this up like you would a drying job. I don’t know whether the air testing that was done concluded specific materials or not, but if it did, concentrate on those materials. If the testing did not provide those types of results than look for suspect materials. Be careful with these materials if they are new. I would rather see a lower temperature and longer duration.
Titan 800 heaters have been used to perform a formaldehyde project on a new condominium in Houston that had extremely high readings of formaldehyde coming from the kitchen cabinetry. They accomplished a significant reduction, well below any levels of concern by OSHA or EPA, but it took five or six days of heating and two or three days of scrubbing. The area of concentration in this project was only the kitchen, but because they were concerned that chemicals had off-gassed and reabsorbed to other porous materials, they also heated the rest of the house. The rest of the house did not require the same duration as the kitchen.
Take as many fans and use as many as the power will allow. Once the vapor pressure is increased and the gasses move to the surface, the air movement removes it and ducting evacuates it from the structure. This is also true of secondary materials. One of the problems that sometimes occurs with building bakeouts is the offgassed materials adsorb to more porous materials, such as carpets, wall coverings, etc. This is why it is extremely important to get as much air turbulence in the space as possible and as much air exchange. You can exhaust the inside air to outside and use the outside air as makeup. The Titan 800 generates airflow in excess of 5,000 CFM.
We developed the GreenTech Heat technology to be efficacious against all forms of insect pests. The convected heat and aggressive airflow also denature VOCs and chemicals in a structure. Give us a call. We are ready to help or consult with any unique applications.