1. NAFA Guide To Air Filtration
Fifth Edition
Industrial Finishing
presented by the
National Air Filtration Association
Industrial Finishing is the term applied involves the spray application of a finish to a product to enhance its characteristics.

2. Typical Automotive Finish Booth
Most people think of cars when thinking of industrial finishes. This is a picture of a typical after-market automotive paint spray booth.

3. Aviation Finishing
But the market for finish filtration is much more, encompassing aviation, wood furniture, lawn mowers and lawn equipment, computer and television screens and just about everything you purchase as a consumer.

4. Industrial Products Finishing
Industrial - Wood Finishing
Industrial products finishing usually is done to accomplish two purposes; 1. To enhance the life of a product by inhibiting deterioration of the material; and 2. to enhance the beauty of the product to make it a more purchasable item.

5. Industrial More Than Automotive
Body Shop
Locations:
> 45,000
» 55,000
Booth Population:
» 110,000
» 70,000
Arrestor Consumption:
85%
15%
Most of the finish operations available to air filter sales is related to production products. These filters are usually changed after every shift.

6. Industrial Finishing Requirements
Almost all industrial processes require clean air to protect a product or process of production.
Clean the incoming air required by the product or process
Blanket the product/process with cleaned air
Offer enough air flow exhausted to keep potentially dirty air away from product/process
Highlight slide points

7. Booth Airflow Makeup Air Intake Air Exhaust Air
All finishing booths have some type of intake air is usually filtered, exhaust air which is most always filtered to remove finish overspray, and makeup air to provide balance. Booths may be positive pressure to the ambient air (to avoid bringing in contaminant through openings in the booth structure, negative pressure to assure that none of the finish being applied gets outside the booth except through the filters, and balanced air. Because overspray filters load and restrict airflow, a sensor is installed to show an imbalance in the booth, and an airflow controller adjusts the system to keep the booth in balance.
Makeup Air

8. Airflow Rate Through a Booth
Airflow through the booth sufficient to remove VOC to levels below 25% of its lower explosive limit Usually 125 to 150 fpm
Flow of air through the booth has to be sufficient to remove the overspray particles and the VOC’s associated with the coating. Velocities of booths vary and must meet the Federal criteria of keeping the VOC below the lowest explosive limit numbers…booth velocities usually run around 135 – 150 fpm.

9. Open-style Finishing Booth
Some booths are just an open-ended square box into which the product is moved for finishing. These are usually less-refined coatings on products that need finishing, but not necessarily for looks – engines and transmissions for example.

10. Booth Types: Crossdraft
Intake Filters
Exhaust Overspray Filters
Some finishing operations utilize a cross-draft air movement. Air is drawn in through an opening, usually some type of doors that have filters installed on them by exhaust fans, over and past the object being worked and through exhaust overspray arrestor filters at the end of the booth. The fan, located behind the arrestor filters then exhausts the air to the ambient environment.

11. Booth Type: Downdraft Ceiling Diffusion Media
Exhaust Overspray Filters
Downdraft booths employ supply fans that provide air to ceiling diffuser media to balance airflow evenly across the work and then remove it through arrestor filters located in the floor of the booth. This type of booth has the advantage of working with gravity to remove overspray and give a uniform flow of air through the booth. They also have drying equipment that allows for air to be filtered and recirculated during curing.
Filtered Supply Air
Heated and Recirculated
During Drying Process

12. Finish Booth Supply Air Filtration
Filters incoming air to the booth or diffusion filter
Usually, door filtration requires pads, links or rolls of media to prefilter the air prior to entry into the finish area.

13. Finish Booth Supply Air Filtration
Designed to provide 99% efficiency on particles > than 5 micron and
Designed to diffuse uniform air flow across the painting
surface.
Ceiling diffusion media comes in panels or typically as roll material and performs two functions – one to clean the air of particles 5 micrometer and larger that will cause blemishes in the finish, and two to diffuse the air evenly across the booth area.
Particles > than 5 microns can cause blemishes to painted surfaces like automobiles so ceiling diffuser media in paint booths is designed to remove 99% of particles 5 micrometers and greater.

14. Finish Booth Exhaust Air Filtration
Typical overspray arrestors are:
Expanded paper-paper & polyester combination
Fiberglass pads -
There are many types of overspray arrestors available including…discuss list.
Overspray arrestor filters are finish specific depending on the characteristics of the finish being applied.

15. Convoluted synthetic pads, Synthetic rolls and cube-style filters
Some finishes require larger surface area to capture and hold higher solids type finish.

16. Baffle Overspray Filters
Baffle-type craftboard cardboard, and styrofoam
Some heavy-solids finish require the overspray to change directions several times which removes the particles from the airstream.

17. Efficiency Minimums For Overspray Filters – 98%
Federal Regulations state that standard overspray filters must have a demonstrated efficiency of at least 98% capture of high solids particles as demonstrated by ANSI/ASHRAE Standard 52.1 MOT.
For aviation filters, they must meet a higher standard due to the chromates found in aviation paint. Filters in 3-stage booths must achieve a solid phase efficiency of greater than 95% on 2.5 micrometer particles. See explanation of 319 Method in Appendix 5 of the NAFA Guide to Air Filtration.

18. Failure of Exhaust Filters to Capture Overspray Finish
Improperly filtering overspray will allow for bypass which coats fans, and ductwork and stacks. It may also be a violation of Federal Regulations.
Exhaust Stack from Industrial Plant

19. Finishing Booth Overspray Filter Disposal
Disposal of filters is critical. They may need to be be stored in air tight containers to avoid spontaneous combustion
Some dispensed filters can not be land filled. Some may need to be incinerated.
Certain specialized industrial paint operations may require specialized filtration. For instance Aerospace, Wood Finishing, Automotive OEM and Auto body shop repair.
The Federal Resource and Recovery Act (RCRA) governs the disposal of hazardous wastes. Some paint overspray filters are considered hazardous waste and must be disposed of in the proper manner. There are 4 characteristics that may indicate overspray filters are hazardous – they are corrosivity, ignitability, reactivity, or toxicity. Filter companies handling overspray filters should check local, State and Federal regulations before handling potentially hazardous material.

20. Sample Questions

21. Two General Categories of Enclosed Finish Booths
Crossdraft
Downdraft
Open-style booths are not “enclosed”

22. When Exhaust Air Exceeds Intake Air ___________must be provided to Replace the Difference
Makeup Air

23. Minimum Demonstrated Overspray Filter Efficiency Must Be at Least ______
98%

24. Overspray Filters May Be Hazardous as Defined by Federal Regulations if they Exhibit Any of Four Characteristics;
Corrosivity Ignitability Reactivity Toxicity

25. Airflow Through a Booth Must Be…
High enough to keep the concentration of VOC vapor held below 25% of its lower explosive limit

26. Thank you.
Questions?