ICS Magazine

AFDs as a Standard Practice

May 4, 2009


Air-filtration devices (AFDs, also known as HEPA-filtration devices, negative-air machines and air scrubbers) are commonly used in water restoration jobs all over the world. These jobs range from clean to grossly unsanitary. In each case, AFDs are providing a valuable service to the customer. It is time that all water-restoration companies get on board and provide AFDs as a standard practice.

Recommending AFD use as a standard practice is, I’m aware, a very strong statement. There are several reasons, though, while I feel it is an appropriate statement to make:
  • IICRC S500 Standard and Reference Guide for Professional Water Damage, 3rd Edition
  • Common Sense
  • A Chorus of Supporters


IICRC S500 Support for the Use of AFDs

The IICRC S500, in my opinion, suggests using AFDs on every job without actually saying it. The first significant reference regarding AFDs relates to situations with strong airflow in a drying environment, which aerosolizes soils:

12.1.20 Controlling Airflow to Accelerate Evaporation: Restorers can install one or more air filtration devices or AFDs (scrubbers), depending on the AFD’s size and obstructions within the structure. AFDs provide additional airflow, while simultaneously removing aerosolized soils or contaminants from the air within a room. Restorers should consider repositioning AFDs on each monitoring trip.

AFDs are also recommended where negative and/or positive pressures are being used to dry cavities:

12.2.2 Restorers should: when drawing moist air out of potentially contaminated cavities using negative pressure, use an in-line HEPA filter to remove contamination from the air before being exhausted into the room.

Since it is unknown what contaminants may be in a wall, floor or other cavity, the safest approach would be filtration of the air exiting the cavity. This can be achieved with an in-line filter or an AFD. Look at the S500 standard, sections 12.3.2.10.2 and 12.3.2.10.3, for more on AFDs and pressure differentials.

Common Sense

Consider the water jobs you’ve performed in the last six months. How many of those jobs have had one of the following conditions:
  • Contamination (as defined in the S500)
  • Drying carpet or carpet and pad in place or floating carpet
  • Structural cavity drying
  • Customers who requested air filtration “At-risk” customers
If your jobs are like most, I’m guessing that 100 percent of the time you’ve encountered one or more of the aforementioned conditions. It’s scary to think that AFDs might not have been used on every one of those water losses.

Any job that involves cleanup of sewage, mold and/or fire damage will generate significant amounts of high-risk or irritating particulate. These contaminants are a direct result of the damage itself, as well as the necessary process of treating and cleaning damaged materials. This includes not only damage in the occupied space, but also contaminants in wall or ceiling cavities that may be disturbed and ultimately introduced into the occupied space.

Even clean-water losses are susceptible to compromised indoor air quality. The high-velocity airflow necessary for effective drying moves more than evaporated moisture into the air; it also stirs up countless microscopic particles that have been trapped in the carpet or other soft goods, or have settled on structural materials.

Ultimately, if these pre-existing or newly introduced contaminants are not removed effectively, they will impact the indoor air quality of the worksite and compromise the quality of the entire restoration job. Some contaminants can even create a potential indoor health hazard.

An air-filtration device helps prevent these undesirable – and potentially harmful – particles from remaining in the indoor environment. Cleaner air also means cleaner equipment during and after the job, reducing the risk of spreading contaminants from one job to the next. By greatly reducing the types and quantity of airborne particles, an air-filtration device also reduces the chances that occupants or technicians will inhale contaminants. Removing contaminants safely, efficiently, and cost-effectively with an air scrubber is a great benefit to your business, your employees, and your customers.

A Chorus of Supporters

If you’ve been in a water class in the last two years, what has been the industry consensus for the use of AFDs? Is there any instructor, class, convention or program in the industry that isn’t calling for the use of AFDs on every job?

Getting paid for using AFDs is normally the only concern that restorers bring up about using them on jobs. Here is a sure-fire way to make sure you get paid for the AFDs you place on a water loss: Every time you place an AFD on a water loss, explain in the estimate why it needed to be placed (refer to Common Sense and S500 above).

How Many AFDs Are Needed?

According to the latest IICRC S520 Standard and Reference Guide for Professional Mold Remediation, “A minimum of four air changes per hour for contaminant ventilation and dilution” is recommended. Therefore, determine the volume of the water loss in cubic feet, multiply by 4 and divide by 60 to determine minimum CFM of air filtration needed.

For example:

7000 CF (Cubic Feet) X 4 ACH(Air Changes per Hour) = 28,000 CFH (Cubic Feet per Hour)

28,000 ÷ 60 (converting Hours to Minutes) = 467 CFM (Cubic Feet per Minute)


Standard Practice

With the ever-increasing emphasis on air quality, customers are expecting clean air along with a restored structure. Restorative drying is all about bringing the structure back to a condition that supports a healthy, clean indoor environment. Think “indoor environmental restoration,” not just “water-damage restoration.” Using air-filtration devices, along with other proper cleaning procedures, is an effective way to exceed customer expectations. It’s time to make AFDs standard practice.