1. Phil Maybee For NAFA Annual Convention 2010
ASHRAE 52.2 Testing?
Phil Maybee
For NAFA Annual Convention 2010

2. Data or Rating?
What Information does Provide?
Does it relate to Real Life?
Should it?

3. Data or Rating?
From the original creators’ idea committees worked on a basic principle –
“create a method of evaluating filters by particle size so end users can have meaningful information to make an educated decision on system protection”
Now 21 years later we are debating whether or not we really want to do that?

4. ASHRAE Standard 52.2
Standardized method of determining fractional size efficiency …..
ASHRAE does not police; audit; train; or verify labs understand the methods in performing the procedure of producing a MERV…

5. ASHRAE Standard 52.2 Minimum Efficiency Reported Value
..of producing a MERV
Minimum Efficiency Reported Value
E-1 – E-2 – E-3 ranges – 12 channels
Air flow rates
Neutralized dust challenge
Single number reported result
Test method supported MERV’s

7. Addendum ‘B’ – added MERV’s 1-4
Arrestance
Amount of LOADING dust caught versus LOADING dust fed in percent by weight
(no particle size relationship)
Dust Holding Capacity
Simply the reported amount of LOADING dust in the filter at the end of the test by weight
(not required for establishment of MERV) )

8. Appendix ‘J’ – Conditioning Step
Voluntary procedure
Two Research Projects led to the method
RP 1189 explore various conditioning methods
RP 1190 determine the particle size affecting performance efficiency and create a challenge dust
Designed to replicate the loss in efficiency of electret enhancement on filter media

9. What does the public hear from US?
“MERV is just a confusion tactic that has been developed recently by filter people – the real testing … is ASHRAE testing”
(comment from a bidder in Florida on facility bid)
“the new minimum thing is okay but what is really important is that we catch 95% of all the germs in the air”
(written comment by filter supplier sent to Hospital in NC)

10. What does the public hear from US?
“electrostatic media conditioning – that’s all garbage – no one uses a filter soaked in alcohol in their building - the important thing is pressure drop and the energy savings” (taken from an to facility director in Houston in response to Appendix J requirement )

11. Some of US get really creative

12. MERV is 11 Years Old Time to change – 52.1 is Gone
Quit using Dust Spot numbers in data sheets
Quit allowing discussion of generic equality between MERV and Dust Spot values
Quit using test data to support something it does not support itself
Quit creating ierv’s and aerv’s and estimated MERV’s

13. Intended performance

14. Lets examine in depth Particle size efficiency charts
Airflow rates
Challenge dust
Dust Holding Capacity
What value does it have?
Appendix J – superfine conditioning
What does this mean?

15. Particle Size Efficiency

16. Size Distribution of Atmospheric Dust Sample
Source: NAFA guide to air filtration
Percent by Particle Count 30
Particle Size (Microns)
0.005% 10
5.0
0.175%
3.0
0.25%
1.0
1.07%
<1.0
98.5%
University of Minnesota

17. As an industry we continue to use data from the 1970’s – there are over 90 papers on superfine particles in a single data search

18. Examine particle size efficiency (in micrometers)
Particle settling in turbulent air – half life in 8 foot room
0.5µ - 41 hours
1.0µ - 12 hours
3.0µ hours
10µ minutes
50µ seconds
100µ seconds

19. Examine particle size efficiency
Airflow has an effect on performance
MERV 8 and less not as much
Particle bounce effect
Seven ranges are available for various usages
118 fpm fpm 295 fpm 374 fpm
492 fpm fpm 748 fpm

20. Examine Particle Size Efficiency

21. Examine Particle Size Efficiency
TEST particles are all potassium chloride
Homogenous features and similar characteristics
Neutralized particles
eliminate the potential of surface charges
Distribution mix?
Is the concentration of range 3 being equal to the concentration of range 1 or 2 normal?

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

23. Examining particle size efficiency
Test Result Consistency ?
Is it an error of the test
Or testing personnel?
Is it the consistency of the media?
ASHRAE 52.1
Generous 7% curve added to values
Two-inch 25 – 30% filters
Consistency is defined by the parameters we choose for boundaries

24. Dust Holding Capacity

25. Examine Dust Holding Capacity
LOADING dust RECIPE is defined in Standard
It is not possible to make dust per the Standard
All labs do not use the same recipe!
Possibly 20% variability within the same lab
Loading steps are defined
Most of the time the first loading (conditioning) causes the initial efficiency to be the MERV
End value of the weight gained in the tested device over entire test is “reported” DHC

26. Real Life?
Challenge Dust
Dust we need to catch
is it relevant?

27. Examine Dust Holding Capacity
Loading Dust particle size is disproportionate to atmospheric dust –
ASHRAE specifies 7.7 Mean Mass particle size for “Arizona Road Dust” – this is not including #7 cotton linters (4mm mesh)
ISO Dust 12103,A2 - …view of volume differential particle size data indicates bi-modal distribution … peaks at 4 and 20 microns

28. NIOSH

29. Does not include cotton linters - ?

30. Particle settling rate vs ISO Fine Loading Dust
8 feet in “Still Air”
0.5µ - 41 hours
1.0µ hours
3.0µ hours
10µ minutes
50µ seconds
100µ seconds
1µ – 3.5 2µ 3µ 4µ 5µ 7µ
10µ
20µ
40µ
80µ
Cotton linters passing thru 4mm screen = 4000 microns

31. Want to have higher DHC ? Change the recipe!
Mass – Density – Porosity – surface shape

32. Examine Dust Holding Capacity
Atmospheric dust is captured by fibers
Pores only become blocked with loading
Gravimetric dust is filtered by pore size
Particle size is matched to media web pores

33. Appendix J Conditioning

34. New Conditioning Step 52-2 already has a Conditioning Step
Loading of 30 grams or .o4” wg
It was thought - “first loading would show drop in performance of electrets”
Spawned ASHRAE research to find what does create the drop in efficiency

35. Research papers RP 1189 Investigation of Mechanisms and Operating
Environments that Impact the Filtration
Efficiency of Charged Air Filtration Media
RP 1190
Develop a new loading dust and dust loading procedures for ASHRAE filter test standards
(KCL Superfines 0.06µ – hours to months ratio)

36. Examine Appendix J It is NOT a discharge procedure
IPA is a discharge procedure
Designed to mimic the deposition of superfine particles and the effects they have on particle collection efficiency
Measuring superfines in “Real Life”
20,000+ per cmᶟ under 0.1 µ (using P-trak)

37. Do the math
16.38 cm³ to in³
1728 in³ to ft³ = cm³ to ft³
28304 x = 566,280,000 particles per ft³
500 fpm = 283,140,000,000 superfine particles
Every minute across every square foot of the filter face area

38. Electret effect
Electret off
Note that when challenge flow is collected on non-electret – it surface loads in direction of airflow. Heavier at face and diminishing to sides.
With electret enhancement note that the coating is uniform over all the surface rather than only the leading surface where the source originates.
Electret on

39. Why it happens?
Superfines are aggressively drawn to the surface of electret fiber
Particles adhere in uniform single layer
Layer starts to insulate the electret enhancement diminishing the surface energy
Particles are too small to assist in mechanical efficiency

40. If it drops in standard test – what happens?

41. Should testing apply to real life?

42. Real Life requirements
USGBC – LEED
New construction requirement
All open ducts in construction sealed or MERV 8 filtration
MERV 13 after completion
Single Point for EB
MERV 13 point for IAQ

43. Real Life requirements
Medical facilities
One micron protection and smaller
Gas Turbines
Two micron protection
Paint application
Five micron protection

44. Real Life Results two buildings same design and size
Building with MERV 8
Building with MERV 13
Particles per cubic foot air
0.3µ - 580,000
0.5µ - 16,400
1.0µ - 3,470
2.0µ - 2,160
5.0µ - 430
Particles per cubic foot air
0.3µ ,000
0.5µ - 5,900
1.0µ - 1,060
2.0µ - 1,520
5.0µ - 260
Outside Air (0.3 – 1.7 million) (0.5 – 38,300) (1.0 – 24,900) (2.0 – 10,600) (5.0 – 910)
Laser particle count data one year from installation date

45. MERV 16 V-cell – Birthing Center

46. Following months
0.3µ µ µ µ

47. Where do we go from 52.2? ISO Standards Rating Systems? 52.3?
Home Depot rating system
AHAM rating system
52.3?
EPA PM 10 and PM 2.5?

48. What will NAFA’s Role be?