1 Residential Air Filtration

2 Residential Issues Cleaner Air –Removal of Particulates –Removal of Odors Maintain Airflow Customers Change Filters

3 Principles of Air Filtration Particulate Phase Straining Impingement (Inertial Impaction) Interception Diffusion Electrostatic Attraction Electrostatic Precipitation

4Straining Fiber Very large particles are captured between two fibers. Airflow Particle Airstream

5 Impingement Fiber Larger particles do not move around the fiber with the airstream and are carried into the fiber due to their momentum. Airflow Particle Airstream

6 Spun Fiberglass Filters Picture provided by Glasfloss Industries, Inc.

7Interception Fiber Midsize particles move along with airstream lines and contact a fiber when they are just close enough. Airflow Particle Airstream

8 Electrostatic Attraction Fiber Airflow Particle Airstream Particles are pulled to the fiber due to electrostatic attraction (charge) of the fiber that is opposite of the particle charge.

9 Electrostatic Attraction Fiber Airflow Particle Airstream Particles are pulled to the fiber due to electrostatic attraction (charge) of the fiber that is opposite of the particle charge.

10 Electrostatic Precipitation Electronic Air Cleaner Particles past through an ionizing section and receive a strong positive charge. These particles are then collected on charged plates. Connected to a voltage source.

11 Residential Air Filter Standard ASHRAE 62.2 “…has three primary sets of requirements…whole-house ventilation, local exhaust and source control..”

12 Residential Air Filter Standard Ventilation - –Minimum Filtration – “MERV 6 or better..” MERV = Minimum Efficiency Reporting Value from ASHRAE

13 Residential Air Filter Standard Definition: Acceptable indoor air quality – “air towards which a substantial majority of occupants express no dissatisfaction with respect to odor and sensory irritation and in which there are not likely to be contaminants at concentrations that are known to pose a health risk.”

ASHRAE 52.2 A design qualification test A destructive test to measure minimum efficiency reporting value (MERV) Efficiency test aerosol is Potassium Chloride (KCl) particles, 0.3 to 10 micron Dust loading aerosol is ASHRAE Standard Test Dust

Copyright National Air Filtration Association 2006 Rev. 2 ASHRAE 52.2 l Initial Resistance l Pressure required to move air through filter at a certain air flow written in inches water, Pascal or millimeters water l Final Resistance l Pressure at which the filter would be considered fully loaded

Exhaust Room Air Outlet Filters ASME Nozzle Downstream Mixer BlowerFlow Control Valve Inlet Filters Aerosol Generator Upstream Mixer OPC Device Section Backup Filter Holder (Used When Dust loading) ASHRAE 52.2 Test Duct Configuration

17 Typical 52.2 Complete Loading Test Data Report Size Range (micron) Fractional Efficiency (%) at Resistance (in H20) Composit e Minimum Composit e Average to E 1 = to to to to E 2 = to to to to E 3 = to to to Minimum Efficiency Reporting Value is 6 at 492 fpm

18 Composite Minimum Curve

19 Table Minimum Efficiency Reporting Value Composite Average Particle Size Efficiency (%) Average Arrestance by ASHRAE 52.1 Minimum Final Resistance 0.3 to 1.0 E to 3.0 E to 10 E 3 PaIn Water 1n/a E 3 < 20A avg < n/a E 3 < ≤ A avg < n/a E 3 < ≤ A avg < n/a E 3 < 2075 ≤ A avg n/a 20 ≤ E 3 < 35n/a n/a 35 ≤ E 3 < 50n/a n/a 50 ≤ E 3 < 70n/a n/a 70 ≤ E 3 < 85n/a n/aE 2 < 50E 3 ≥ 85n/a n/a50 ≤ E 2 < 65E 3 ≥ 85n/a n/a65 ≤ E 2 < 80E 3 ≥ 85n/a n/aE 2 ≥ 80E 3 ≥ 90n/a E 1 < 75E 2 ≥ 90E 3 ≥ 90n/a ≤ E 1 < 85E 2 ≥ 90E 3 ≥ 90n/a ≤ E 1 < 95E 2 ≥ 90E 3 ≥ 90n/a E 1 ≥ 95E 2 ≥ 90E 3 ≥ 90n/a3501.4

20 Table Minimum Efficiency Reporting Value Composite Average Particle Size Efficiency (%) Average Arrestance by ASHRAE 52.1 Minimum Final Resistance 0.3 to 1.0 E to 3.0 E to 10 E 3 PaIn Water 1n/a E 3 < 20A avg < n/a E 3 < ≤ A avg < n/a E 3 < ≤ A avg < n/a E 3 < 2075 ≤ A avg n/a 20 ≤ E 3 < 35n/a n/a 35 ≤ E 3 < 50n/a n/a 50 ≤ E 3 < 70n/a n/a 70 ≤ E 3 < 85n/a n/aE 2 < 50E 3 ≥ 85n/a n/a50 ≤ E 2 < 65E 3 ≥ 85n/a n/a65 ≤ E 2 < 80E 3 ≥ 85n/a n/aE 2 ≥ 80E 3 ≥ 90n/a E 1 < 75E 2 ≥ 90E 3 ≥ 90n/a ≤ E 1 < 85E 2 ≥ 90E 3 ≥ 90n/a ≤ E 1 < 95E 2 ≥ 90E 3 ≥ 90n/a E 1 ≥ 95E 2 ≥ 90E 3 ≥ 90n/a E 1 = 9.8% E 2 = 27.2% E 3 = 44.8% MERV 6

21 MERV MERV then is an efficiency number for particle removal… Gas-phase removal numbers are not mentioned in the standard…

22 Gaseous Contaminant Removal Principle Methods Physical – Adsorption –Activated carbons Chemical - Chemisorption –Chemically treated activated carbons –Potassium permanganate impregnated media

23 Principle Methods Adsorption - The process by which one substance is attracted and held onto the surface of another. –It is a surface phenomena. –Capacity is independent of particle size –Adsorption rate is inversely proportional to particle size.

24 Principle Methods Chemisorption - The result of chemical reactions on and in the surface of the adsorbent. –Fairly specific and depends upon chemical nature of media and the contaminant –Irreversible and essentially instantaneous

25 Gas Phase Contaminants Where in the home? –Bathroom –Kitchen - biggest –Laundry room –Garage –Trash storage area –Pet area –Smoking household

26 Pressure–Velocity In the attempt to increase residential air filtration efficiency, little attention has been paid to the problem associated with increase pressure drop Lower flow rates Premature equipment failure Bypass leakage in ductwork

27 Project: Test Pressure Drop with 3 Types of Residential Filters Test Facility – one story 1800 sq. ft. condominium Unit – 3 yr. old constant speed gas/ac unit Motor – 1/3 hp with max. 0.5” w.g. external static Filter Grille and extended surface filter installation

28 Test Protocol Fan turned to the “On” position All filters removed Readings taken with calibrated flowhood on return air grille No filter installed: 0.30” w.g. 848 cfm

29 Filters Used Filter #1 – 1” standard fiberglass throwaway Filter ” w.g. 842 cfm

30 Filters Used Filter #2 - 1” mini-pleated extended surface filter Filter ” w.g. 798 cfm

31 Filters Used Filter #3 - 5” Extended surface unit- mounted filter Filter ” w.g. 811 cfm

32 Summary Filter #1 – 1% decrease in flow 848 to 842 – 0.35 ΔP Filter #2 – 6% decrease in flow 848 to ΔP – starts out clean at max. ext. static Filter # 3 – 4% decrease in flow 848 to 811 – 0.4 ΔP

33 Discussion Is this a problem that needs further testing? Group said “Yes” Does this information need to be made known to residential purchasers? Group said “Yes” How? Group said “Label Package”

34 You Can Help 1. Install MERV 6 filters (extent of system pressure). 2. Size return to keep pressure correct in system – ACCA Manual D – Friction Rate Worksheet 3. Contact local NAFA representative if you need help

35 National Air Filtration Association (NAFA) The mission of NAFA is to conduct education and certification programs for members and end-user personnel; To provide forums for the exchange of information about technical standards, government regulations, and product information; To educate consumers about the importance of air filtration and NAFA's certifications; to certify air filtration products; to set field performance standards for products.

36 NAFA Programs NAFA Certified Air Filter Specialist - CAFS NAFA Certified Technician - NCT NAFA Product Certification

37 NAFA How we can help you… –Over 600 members - air filtration manufacturers and distributors –United States and 12 foreign countries –