NAFA Technical Seminar April 19, 2012

1. NAFA Technical Seminar • April 19, 2012 ANSI/ASHRAE 52.2 Can we fix this Method of Test?

2. History of the Test procedure • 10+ years in development prior to 1999 release • Task of 52.2 Committee "create a test method based on particle size removal efficiency for end user evaluation of filter performance" • Research projects led to greater understanding of the physical science in filtration • MERV - scales were created with minimal data and educated guesses at value spread

4. Committee Efforts • Std published in 1999 for the first usage • No revisions through 2007 (other than edits) • 2008 Arrestance and DHC were added from 52.1 predominantly for MERVs 1-4 • 52.1 was removed from ASHRAE Standards • Addition of "Voluntary Conditioning Step"

5. MERV's Status? • ASHRAE Rating system? • No certification of personnel performing tests • No policing entity to produce a rating system

7. ISO Standards • Working groups creating standards for • Cleanroom and HEPA usage completed • UVC, Rotating Equipment, dust collection • Working group 3 - General HVAC filtration is looking to use 52.2 MOT for developing PM efficiency values

8. Filter Rating Definition: • System of classification according to merit or amount • Assessment of something in terms of quality, quantity or both • What filter parameters should be included? • Filter Performance – pressure drop, efficiency, life • Energy • Perceive Value • Cost

9. Filter Rating • Is it possible to combine filter performance characteristics into one criterion? • Greater value of the criterion equal to “better” filter • Traditional quality factor (figure of merit): • E – filter efficiency and ΔPo – filter pressure drop • Potential issues: • Different ΔPo units • Results at different flow rate

10. Filter Rating • Example 1: E1 = 80% and ΔPo = 0.40” H2O α1 = - ln (1 – 0.8)/ 0.40 = 1.609/0.40 = 4.02 • Example 2: E1 = 80% and ΔPo = 0.30” H2O α2 = - ln (1 – 0.8)/ 0.30 = 1.609/0.30 = 5.36 • Example 3: E1 = 85% and ΔPo = 0.40” H2O α2 = - ln (1 – 0.85)/ 0.40 = 1.897/0.40 = 4.74

11. Filter Rating • Single Aggregate Objective Function (AOF) • Weighting method, linear AOF: MAX • E – filter efficiency; ΔPo – filter pressure drop • C – filter cost; DHC – filter dust holding capacity • λ – weighting factors; ∑ λi = λ1 + λ2 + λ3 + λ4=1 • λ – weighting factors are assigned based on priority - subjective

12. Filter Rating • Combination of objectives: • Other objectives: Cost, Energy

13. Filter Rating - Examples • MERV – is MERV a rating system? • Residential filters – Home Depot • FPR (Filter Performance Rating) = 1 – 10 scale Weighted Average = λ1(Efficiency Large Particles) + λ2(Efficiency Small Particles) + λ3 DHC λ1 + λ2 + λ3 = 0.6 + 0.3 + 0.1 =1 • FPR = 10 for Weighted Average > 25 • Residential filters – 3M • MPR – Microparticle Performance Rating ability to capture particles 0.3 – 10 µm (E1)

14. According to ASHRAE and IEST – 20 Possible Assignable MERV’s Three “Markets” E3 Arrestance MERV 1-4 General Equipment E2 Middle Efficiency MERV 5-12 Equipment and People E1 High Efficiency MERV 13-20 Marginalized Health People and Specialized End Uses Real Differences Between the Markets Arrestance High Efficiency Real Differences Within These Markets MERV 5 MERV12 Difficulties Variety of End Uses Variety of Air Handling Types Variety of Pollutants “Too Many MERV’s” ??

15. Conditioning Step is Too Expensive

16. Conditioning Step Not Real World Mechano-Electret Filter Mechanical Only Filter

17. 52.2 Positive Attributesbefore Conditioning

18. Analogy—Gas Mileage Testing http://www.caranddriver.com/reviews/2012-ford-focus-sel-test-review

19. ASHRAE 52.2-2007 Tom Justice

20. 2010 Round Robin

21. 2011 Round Robin

22. Issues under Review by Task Groups • Current MERV boundaries • Humidity Range • OPC particle counter specifications • Air density calculation • Shedding • IPA vapor conditioning • Test variability

23. Reported Values

31. Issues under Review by Task Groups • Current MERV boundaries • Humidity Range • OPC particle counter specifications • Air density calculation • Shedding • IPA vapor conditioning • Test variability

32. Fig. 8 ASHRAE 1287 RP

33. KCL @ 0% to 85% RH

34. Other Potential Issues • Test dust • Specifications for particle generator • Radioactive versus corona discharge in neutralization of airstream • Initial resistance calibration