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

Data or Rating? What Information does 52.2 Provide? Does it relate to Real Life? Should it?

Data or Rating? From the original creators’ idea - 52.2 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?

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…

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 5 - 16

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) )

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

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)

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 e-mail to facility director in Houston in response to Appendix J requirement )

Some of US get really creative

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

Intended performance

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?

Particle Size Efficiency

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 - 1972

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

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 - 1.5 hours 10µ - 8.2 minutes 50µ - 14.6 seconds 100µ - 5.8 seconds

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 246 fpm 295 fpm 374 fpm 492 fpm 630 fpm 748 fpm

Examine Particle Size Efficiency

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?

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)

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

Dust Holding Capacity

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

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

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

NIOSH - 1978

Does not include cotton linters - ?

Particle settling rate vs ISO Fine Loading Dust 8 feet in “Still Air” 0.5µ - 41 hours 1.0µ - 12.4 hours 3.0µ - 1.8 hours 10µ - 7.8 minutes 50µ - 13.5 seconds 100µ - 4.6 seconds 1µ 2.5 – 3.5 2µ 10.5 - 12.5 3µ 18.5 - 22.0 4µ 25.5 - 29.5 5µ 31.0 - 36.0 7µ 41.0 - 46.0 10µ 50.0 - 54.0 20µ 70.0 - 74.0 40µ 88.0 - 91.0 80µ 99.5 - 100 Cotton linters passing thru 4mm screen = 4000 microns

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

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

Appendix J Conditioning

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

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)

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)

Do the math 16.38 cm³ to in³ 1728 in³ to ft³ = 28304 cm³ to ft³ 28304 x 20000 = 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

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

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

If it drops in standard test – what happens?

Should testing apply to real life?

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

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

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 - 153,000 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

MERV 16 V-cell – Birthing Center

Following months 0.3µ 0.5µ 1.0µ 2.0µ

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?

What will NAFA’s Role be?