1. Outline 7-1 Comparing Test Methods 7-2 Review of Filtration Mechanisms
7-3 Methods to Measure the Fractional Penetration
7-4 Photometer use in Filter Testing
7-5 Summary of Test Method Comparisons
7-6 Effects of Loading on Filter Media
7-7 Filter Testing with Larger Particle Sizes
7-8 Filter Performance, Rating and Standards
In this portion of the Short Course we will be
Comparing Test Methods
Review of Filtration Mechanisms
Methods to Measure the Fractional Penetration
Photometer use in Filter Testing
Summary of Test Method Comparisons
Effects of Loading on Filter Media
Filter Testing with Larger Particle Sizes
Filter Performance, Rating and Standards

2. The Two Key Parameters in Air Filter Testing
Pressure Drop
Filter Efficiency

3. Key Parameters Pressure Drop Filter Efficiency
At lower velocities pressure drop is linear with velocity
Best results when measured close to filter and in long straight section of duct
Filter Efficiency
More complicated behavior that depends on flow and:
Particle properties
Detector Type
Particle Concentration
Other factors including humidity

4. 7-1 Comparing Test Methods
Factors that affect test results
Test Method Factors
Particle Size Distribution
Particle material (liquid or solid)
Particle Charge Level
Other (flow rate, ??)
Media Factors
Filter Penetration Curve
Filter Media Structure and Charge Level
There are three main elements that determine what the filter test results will be:
Aerosol Size Distribution
Filter Penetration Curve
Filter Media Structure
Other factors such as flow rate are also important

5. 7-2 Review of Filtration Mechanisms
7-2-1 Filter Efficiency and Particle Penetration Calculations
Downstream Concentration Upstream Concentration
Penetration, P =
%P = x P
Efficiency, E = P
First I will start with a review of Air Filtration which I assume Dr. Ken Rubow covered:
The basic measurement is Penetration which is
Downstream divided by Upstream Concentration
From that you can get % Penetration, Efficiency, and % Efficiency
An important concept is MPPS and the fact that filters have a most penetration or least efficient particle size. Typically between 0.1 and 0.3 microns for mechanical filters but as low as 0.05 microns (50 nm) for electrostatic or membrane filters
%E = x E = %P
Most Penetrating Particle Size, MPPS: typically between 0.05 and 0.3 µm

6. 7-2-2 Filter Efficiency Testing
Particle Conditioners
Drier • Neutralizer
Electrostatic Classifier
Particle Generation
Salt
Oil
Dust
PSL
Bacteria
Etc.
Particle Generation
Particle Conditioners
Neutralizers
Aerosol stream
Radioactive
Soft X-Rays
In Makeup Air
Corona Ionizer
Particle Conditioners
Drier
Neutralizer
Radioactive or Soft X
Electrostatic Classifier
Particle Detectors or Sizers
3330 OPS
8587A Photometer
7110 Particle Counter
3772 CPC with or without Electrostatic Classifier
Particle Detectors or Sizers
Photometers
Condensation Particle Counters (CPCs)
Optical Particle Counters (OPC’s)
Laser Particle Counters (LPC’s)
Aerodynamic Particle Sizers
Mass Detector
Gravimetric Filter
Particle Detectors or Sizers

7. 7-2-3 Mechanisms of Particle Capture
Diffusion
Interception
Inertial Impaction
Electrostatic Deposition
Action of Brownian motion. Best capture with small particles, fine fibers and low velocities. Independent of particle density.
Particles travel along streamlines and are caught because of their size. Ratio of particle to fiber size is important.
Particles deviate from the streamlines due to inertia and impact on the fibers. Large particles, high density, high velocity and small fibers is most efficient.
Particle is attracted to the fiber by electrical forces.
Electrostatic Attraction
Inertial Impaction
Animation version (for presentations)
(-)
(+)
Filter
Fiber
Brownian Diffusion
Interception

8. Filter Penetration as a Function of Particle Size
100
Most Penetrating Particle Size (MPPS) 10
Inertial Impaction
Diffusion 1
% Penetration
and
Interception
Diffusion
and
Interception
0.1
This slide shows the effect of the mechanisms and how that results in a Most Penetration Particle Size (MPPS)
No Sieving
0.01
0.001
0.01
0.1 1 10
Particle Diameter ( m m)

9. DIFFUSION
LOWER
VELOCITY
INTERCEPTION
MPPS
Effect of Particle Deposition Mechanisms and Flow Rate (Face Velocity) on Penetration and Most Penetrating Particle Size
I have added this slide (Not in your notes) to illustrate two things.
First you can see how the penetration curve results from Diffusion and Interception.
Second, you can see how changing velocity changes Diffusion only resulting in a penetration curve that changes both Penetration value and MPPS

10. 7-2-4 Equilibrium Particle Charge Distribution
Charge Level varies with particle size
Dia. -2 -1 +1 +2 10
0.00
5.03
90.91
4.10 20
0.02
11.14
80.29
8.54
0.01 40
0.39
19.00
65.10
14.67
0.29 60
1.97
24.48
54.00
18.57
1.11 80
3.75
26.48
47.50
20.50
2.80
100
5.67
27.42
42.36
20.75
3.24
200
12.18
25.54
29.96
19.65
7.21
400
14.83
20.66
21.22
15.60
9.09
600
14.69
17.27
16.55
12.91
8.60
800
13.82
15.08
14.15
11.20
7.91
1000
12.86
13.33
12.36
10.24
7.59
This Diagram shows what is called a Boltzman or Fuchs Equilibrium Charge Distribution for submicron particles. Charge level increases dramatically with increasing particles size. This affects penetration when the filter media is charged.
If a filter test uses generated aerosol and it has NOT been neutralized (brought down to an equilibrium charge level) it can have much higher charge level than this diagram shows and that will make the filter look much better than it would be in real life situations.

11. Filter Efficiency Curve
DIFFUSION
AND
INTERCEPTION
INERTIAL
IMPACTION
NEW This diagram shows an Efficiency curve (instead of Penetration) for those of you who are more comfortable with Efficiency.
Efficiency is just the inverse of penetration.
In this graph we have a linear scale for efficiency instead of Log.

12. 7-3 Methods to Measure Fractional Penetration
Two methods for measuring fractional penetration
1 Monodisperse Aerosol and Non-size Discriminating Detectors
- precise control over particle size
- higher accuracy in penetration measurement
- longer test time required
2 Polydisperse Aerosol and Size Discriminating Detectors
- fast test
- less accuracy in concentration measurement due to interference of different particle sizes
To measure Fractional Penetration (or Efficiency) you need to have either:
Monodisperse Aerosol <- Start with this or
a Size Discrimination Detector
Penetration curve is helpful to see the effect of particle size and distribution on Penetration and Efficiency test results.

13. Monodisperse Sub m Aerosol Generation
1. An atomizer produces a polydisperse aerosol.
2. The aerosol passes thru a DMA (differential mobility analyzer).
3. A monodisperse aerosol of known particle size (0.01~1 m) is produced.
To create Monodisperse Particles below 1 micron a DMA (Differential Mobility Analyzer) is frequently used. It behaves like a “notch” filter for particles (for those of you that know that term). It only lets one size through at a time. It does this sorting based on the Electrical Mobility of the particles.
There is an electrical field between the grounder outer wall and the inner charged wall. Smaller Particles hit the center rod higher up than larger particles. Only one size of particle gets through the slit near the bottom of the rod. By varying the rod voltage (and/or the flow rate through the tube) the particle size can be changed to cover the range from 10 nm to 1 micron.

14. Condensation Particle Counter (CPC)
A non-size discriminating detector
Counts particles efficiently down to 0.01mm or smaller
Very wide dynamic range for concentration measurement
With a Monodisperse Aerosol the detector doesn’t need to measure size. For very small particles (<0.1 micron) the main detector that is uses is called a Condensation Particle Counter or CPC. Also know as CNC condensation “Nucleus” counter.
This type of detector “Grows” the particles by condensing a vapor (usually alcohol) onto the particle to grow it in size to make it easier to count.

15. Butanol CPC Key components
To Pump
Butanol CPC Key components
40 °C
Optics
Three Basic Components
Saturator
Heated to produce vapor from Butanol
Condenser
Cooled to cool particles
Vapor condenses onto particles and they grow
Optics
Count particles
~ 10 µm °C
Condenser
Saturator 39  0.2 ºC Condenser 22  0.2 ºC Optics 40º C
3790 – CPC-100 Saturator º C (nominal 38.3º) Condenser º C (nominal 31.7º) Optics 40º C
3775 Saturator 39  0.2 ºC Condenser 14  0.2 ºC Optics 40º C
Saturator 39  0.2 ºC Condenser 10  0.2 ºC Optics 40º C
Saturator XX  0.2 ºC Condenser XX  0.2 ºC Optics XXº C
39 °C
Saturator
Sample Flow

16. Example of a Fractional Efficiency Filter Tester
Summary:
Generate oil or salt aerosols which is then size selectively classified based on users input (in case large particle sizes are needed, a bleed flow system is used).
Particles are detected using upstream and downstream CPC.
Entire operation is computer controlled.

17. Scanning Mobility Particle Sizer (SMPS)
A size discriminating system
Scanning through a range of sizes and correlating the counting results with the size range covered results in a size distribution measurement
Voltage
Reliable high voltage supply & electronics
Calibrated using NIST Traceable meters
Flow
Re-circulating flow scheme
Can be modified to condition Sheath Air before going into DMA
Flow meters used to control pump flow
Volumetric flow rate: atmospheric temperature & pressure adjustment.

18. Counting Detector at MPPS [Monodisperse Aerosol]
Particle Diameter
Penetration
This shows the penetration you would get from a monodisperse aerosol at the MPPS

19. Fractional Penetration Curve [for monodisperse aerosol]
Particle Diameter
Penetration
This shows the same result with other sizes also used to get a penetration curve.

20. Counting Detector at MPPS [for polydisperse Aerosol]
Particle Diameter
Penetration
In this slide a Polydisperse Aerosol is used. Since it has a wider size distribution the penetration will be lower than it would have been for a Monodisperse Aerosol

21. 7-4 Photometer used in Filter Testing
Light Scattering Photometer
Measurements are made with a laser-based, light scattering Photometer.
The Laser is focused where particles pass through the optical region and scattered light is collected on a detector.
This slide shows an example of a photometer. In this case some of the aerosol is filtered to create a sheath flow around the aerosol to keep the inside of the optics region clean and to reduce maintenance.

22. Light Scattering Photometer Response
In Sub-micrometer size range the response is Diameter to the sixth power
From diameters that are approximately that of the wavelength of light the response is Diameter squared
Photometer based testers are used for sub-micrometer sized particles

23. Photometer Detector with Polydisperse Aerosol [CMD Centered at MPPS]
Particle Diameter
Penetration
Count Distribution
Photometer Distribution
This slide shows the same polydisperse aerosol as in the count detector example but shows what the result would be for a Photometer (D^6) detector.
Effective size distribution with a Photometer Detector shifts to larger sizes because of D6 response of Photometers

24. Normalized distributions of Oil Aerosol
Aerosols for photometer testing
Oil Generators (Shape adjusted Distribution)
Normalized distributions of Oil Aerosol
This example shows the Aerosol Size Distribution for what has been called “0.3 Micron Monodisperse DOP Aerosol”.
As you can see it is not Monodisperse nor is it 0.3 micron in size (at least not count but it is close in mass).
The Mass and Photometer distributions are calculated from the count distribution using D^3 and D^6 times the count at all sizes.
When this aerosol is used with a photometer detector (as the DOP test methods usually specify) the aerosol acts like it is much large in size (about 0.4 microns)
CMD=190 nm, GSD=1.6

25. Count, Mass, Photo Correlation for Oil at 85 lpm
This slide shows what theory predicts for three detector types with layers of mechanical filter media.
In this case the MPPS of the filter media is approximately 0.15 microns.

26. Normalized distributions of NaCl Aerosol
Salt Generators
Normalized distributions of NaCl Aerosol
This is the aerosol size distribution for an aerosol that meets the requirements for the NIOSH 42 CFR part 84 standard for respirators. The CMD is microns and the (GSD) geometric standard deviation (or width of the distribution) is 1.75.
With GSD 2/3 of the particles are within the size range from the mean times and divided by the GSD value. Aerosol Size Distributions are normally bell shaped curves on a Log size scale.
Note that the Count and Mass distributions are on either side of the MPPS of the filter used in the previous (oil aerosol) example.
CMD=78 nm, GSD=1.75

27. Count, Mass, Photo Correlation for NaCl at 85 lpm
In this graph you see the effect of that. The Count and Volume (or mass) results are almost the same but the photometer results are much lower in penetration. This is for the same filter media that was used for the oil example.

28. Aerosol Size Distributions
This slide shows the formulas that are used in calculating penetrations with different types of detectors. In all cases penetration is Downstream divided by Upstream.

29. 7-5 Summary of Filter Testing Methods
7-5-1 Aerosol Generation
General Size Characterization
CMD (Count Medium Diameter) or MMD (Mass Medium Diameter)
GSD (Geometric Standard Deviation)
Actual Size Characterization
SMPS – Scanning Mobility Particle SizerTM Spectrometer
Mass Concentration
Number Concentration
Time Stability of Output
Charge Distribution
To Summarize what we have covered so far the aerosol generation produces a distribution that can be described in a number of ways.
Which distribution is important depends on the detection method you are using.
Stability and charge of the aerosol can also dramatically effect test results.

30. 7-5-2 Filter Characteristics
Filtration as a Function of Particle Size
Most Penetrating Particle Size (MPPS)
Typical MPPS
Mechanical Media:
100 nm < MPPS < 300 nm
Electro-Static and Membrane:
MPPS< 100 nm
For Air Filters,
Filtration is a function of particle size
Air filters all have a MPPS
For mechanical filters the MPPS is between 0.1 and 0.3 microns
For electrostatic and membrane media I have seen as low as 30 nm (0.03 microns)

31. 7-5-3 Measurement Performance
Resulting penetration is a function of instrumentation, challenge aerosol, and filter characteristic
Resulting penetration measurement is not significant without knowledge of filter characteristics and challenge aerosol
Resulting penetration is a function of instrumentation, challenge aerosol, and filter characteristic
Resulting penetration measurement is not significant without knowledge of filter characteristics and challenge aerosol
Even the same equipment can give different results if not all of the settings are the same.

32. 7-5-4 Approaches Counting Detector at MPPS
Particle Diameter
Penetration
Counting Detector at MPPS
[Monodisperse Aerosol]
Particle Diameter
Penetration
Fractional Penetration Curve
[Monodisperse Aerosol]
Particle Diameter
Penetration
Photometer Detector
[Polydisperse Aerosol -
CMD Centered at MPPS]
Count Distribution
Photometer Distribution
Particle Diameter
Penetration
Counting Detector at MPPS
[Polydisperse Aerosol]
This slide summarizes the effects of particle size and size distribution on penetration as well as the effect of detector type of penetration results.

33. 7-6 Effect of Loading on Filter Media
0.001
0.01
0.1 1 10
100
200
300
400
500
600
Loading Level (mg)
% Penetration
Mechanical
NaCl
DOP
Electrostatic
This slide shows the effect of filter loading on filter penetration.
In the past the assumption was that filters get more efficient as they load.
As you can see from the chart this isn’t true.
For electrostatic media with oil I have seen penetrations increase as much as two orders of magnitude. The effect is coating the charge sites on the filter media with oil that masks the charge, making it much less effective.
The coating of fibers with oil (which increases the air velocity through the filter media) can cause some increase in penetration of mechanical filter media.
Solid (salt) particles can also collect on charge sites in filter media making the charge less effective.
Only solid particles an mechanical media gives always decreasing penetration with loading

34. 7-6-1 Initial Filter Loading Behavior
Electrostatic DOP
Droplet deposit on charge sites masking them and increasing penetration
Mechanical DOP
Filling voids with oil increases velocity, increasing penetration
Electrostatic NaCl
Particles deposit on charge sites covering them and increasing penetration
Mechanical NaCl
Decreasing penetration
Electrostatic DOP
Droplet deposit on charge sites masking them and increasing penetration
Mechanical DOP
Filling voids with oil increases velocity, increasing penetration
Electrostatic NaCl
Particles deposit on charge sites covering them and increasing penetration
Mechanical NaCl
Decreasing penetration

35. 7-6-2 Electrostatic Media Loading
Depends on the nature of the aerosol
Solid particles build up on the charge sites and build dendrites that add to the efficiency of the media. Some loss of efficiency due to shielding of the electric charge sites occurs.
Liquid particles spread out and shield the electric charge sites very efficiently. This shielding can cause a significant increase in filter penetration.
+ + +
Loading
Solid Particles
+ + +
Loading
Liquid Particles

36. 7-7 Filter Testing with Larger Particle Sizes
Filtration Efficiency (%)
Efficiency Curve that covers size range of interest for ASHRAE type filters
Particle Bounce is an issue for large sizes and low efficiency filters
For filters that are not very efficient, it is convenient to test them at larger particle sizes where the efficiency is better. Ventilation filters are one example of this type of filter.
This slide shows the efficiency curve for a typical ASHRAE grade media.
Note that for large sizes the penetration can drop due to particle bounce. This usually occurs for particle approximately 6 microns and larger and only for low efficiency filter media.

37. 7-7-1 ASHRAE 52.2 Test Standard
Furnace filters to near HEPA grade
Efficiencies from %
Particle Sizers µm
Solid-phase test aerosol
Aerosol particle counter to measure upstream and downstream
Conditioning step
Blower (3000 cfm at 13 in. H2O)
Test Filter housing

38. MERV table from ASHRAE 52.2 standard
Minimum Efficiency Reporting Value
Composite Average Particle Size Efficiency
Minimum Final Pressure Drop
MERV Value E1
0.30 to 1.0 E2
1.0 to 3.0 E3
3.0 to 10.0
Inches of Water 1
N/A
E3 <20 & Arrestance <65
0.3 2
E3 <20 & 65 ≤ Arrestance <70 3
E3 <20 & 70 ≤ Arrestance <75 4
E3 <20 & 75 ≤ Arrestance 5
20 ≤ E3 <35
0.6 6
35 ≤ E3 <50 7
50 ≤ E3 <70 8
70 ≤ E3 9
E2 < 50
85 ≤ E3
1.0 10
50 ≤ E2 <65 11
65 ≤ E2 <80 12
80 ≤ E2
90 ≤ E3 13
E1 < 75
90 ≤ E2
1.4 14
75 ≤ E1 <85 15
85 ≤ E1 <95 16
95 ≤ E1
95 ≤ E2
95 ≤ E3
This is the table from the ASHRAE 52.2 standard. This is a way to summarize the results of the fractional test.
MERV stands for Minimum Efficiency Reporting Value. Since loading with dust makes causes the efficiency to increase the values for the initial efficiency curve are usually what is used to determine the MERV.
Loading is used to get an idea of how a filter would perform in use.
The test can be used to cover a wide range of filter efficiencies.
The ASHRAE committee that worked on this standard is trying to work on a conditioning step and trying to get a new loading dust to better simulate real life filter behavior.
Arrestance is a gravimetric (weight) type of test.

39. 7-7-2 Filter Efficiency Curves for typical ventilation filters (ASHRAE 52.2)
These curves are examples of efficiency curves for some of the MERV values
Cautions when using Particle Counters - Coincidence
Particle Counters count individual particles as pulses. With high concentrations, some pulses actually are the overlapping of multiple pulses. Most counters don’t know that this has occurred. Total count will be Down and the Size distribution shifted to larger sizes
SAE example In a round robin test a few years ago the efficiency in the m size channel gave results that varied from 20 – 80 % efficiency for one small lot of matched filters. One lab also reported > - 400% efficiency on their filter.
A general rule of thumb is to not exceed 5-10% of the manufacturers specified maximum concentration for OPC’s and LPC’s.
Procedures to check for the effect of coincidence are built into some of the standards such as ASHRAE The basic procedure is to measure the efficiency curve and then lower the concentration by at least a factor of 2.

41. 7-7-3 Problems with Particle Counters OPCs as Detectors
Coincidence causes undercounting of smaller sizes Upstream of Filter (Larger sizes over counted)
This can dramatically effect Efficiency Measurements
If done properly OPCs (Optical Particle Counters) can be effective

42. 7-8 Filter Performance, Ratings and Standards
Not all filter tests use particles in air to rate filters. Some tests are based on the pore sizes of the filter.
A filter is rated “absolute” for particles larger than it’s larges pore size. If absolute is used to describe a filter in general it is not accurate since if air can get through a filter some particles can get through.
Pore size ratings and bubble point measurements are an evaluation of the pore structure of the filter media.

43. 7-8 Filter Performance, Ratings and Standards
7-8-1 Filter Ratings
·        “Absolute”
·        Liquid rated “pore” size
·        Smallest measurable particle size
·        Bubble Point
·        Mean flow pore size
Not all filter tests use particles in air to rate filters. Some tests are based on the pore sizes of the filter.
A filter is rated “absolute” for particles larger than it’s larges pore size. If absolute is used to describe a filter in general it is not accurate since if air can get through a filter some particles can get through.
Pore size ratings and bubble point measurements are an evaluation of the pore structure of the filter media.

44. 7-8-2 Porometry for filter pore sizes
Wet, Dry and Half-dry curves
Porometry (Bubble Point Testing) is done by putting a fluid over a filter and using air pressure to force bubbles through the filter media. Using either a wetted filter or a dry filter gives different air flow rates and these values are used in rating the filter.
See Porous Materials, Inc for more information

45. Pore size distribution
When the rate of change of air flow is used a pore size distribution can be determined. Here is an example.

46. Porometry Instrument Schematic
This is a schematic of one of these systems.

47. 7-8-3 Filter Performance Terminology
Fractional Penetration = =
Log Reduction Value = LRV
= log
Beta Ratio =
1 – Collection Efficiency
Downstream Concentration Upstream Concentration
( )
Upstream Concentration Downstream Concentration
In addition to Penetration and Efficiency other terms are used such as Log Reduction Value and Beta Ratio.
LRV is the log of the upstream divided by the downstream concentration.
The Beta Ratio is the upstream divided by the downstream concentration.
( )
Upstream Concentration Downstream Concentration

48. Equivalent Description of Filter Performance
For a filter with
10,000 upstream particle counts
10 downstream particle counts
Particle Collection Efficiency = 99.9%
Fractional penetration = 0.001
Percent Penetration = 0.1%
Beta Ratio = 1000
Log Reduction Value = 3
So for a filter that has a 99.9% efficiency,
the fractional penetration is 0.001,
the % penetration is 0.1,
the Beta Ratio is 1000
and the Log Reduction value is 3.
This case represents an example where 10,000 particles are counted upstream for every 10 particles counted downstream.

49. 7-8-4 Standards ASTM and MIL-STD 282 di-octyl phthalate (DOP) test
Some examples
ASTM and MIL-STD 282 di-octyl phthalate (DOP) test
HEPA filter test
ASTM latex sphere test
ASHRAE ventilation grade filter tests (52.1 and 52.2)
SAE engine air intake filter and cabin air filter tests
NIOSH respirator filter tests (30 CFR part 11 and 42 CFR part 84) 
This is a list of some of the commonly referred to standards.

50. US Government Agencies that have Filtration Standards
Department of Energy (DOE)
National Institute for Occupational Safety and Health (NIOSH)
US Military Standards (MIL-STD)
These are some of the government agencies that make filtration standards

51. Domestic Organizations with Filtration Standards
AHAM Association of Home Appliance Manufacturers
ANSI American National Standards Institute
ARI Air Conditionings and Refrigeration Institute
ASHRAE American Society of Heating, Refrigerating, and Air Conditioning Engineers
ASME American Society of Mechanical Engineers
ASTM American Society of Testing and Materials
CAGI Compressed Air and Gas Institute
IEST Institute of Environmental Science and Technology
NSF Nation Sanitation Foundation
SAE Society of Automotive Engineers
SEMI Semiconductor Equipment and Material International
UL Underwriters Laboratory
These are organizations in the US that have filtration standards.

52. International Organizations with Filtration Standards
ISO International Organization for Standards
BSI British Standards Institution
CAN National Standard of Canada
DIN German Institute for Standardization
JIS Japanese Industrial Standards
EN European Norms
CEN European Committee for Standardization (Comité Européen de Normalisation)
These are some of the international organizations that have filtrations standards.

53. Applications areas for Filtration Standards
Building ventilation filters
Industrial air cleaning
Clean Rooms
Pharmaceutical industry applications
Nuclear facility filters
Engine air intake filters
Automotive cabin air filters
Vacuum cleaner filters
High purity gas filtration
Filtration Standards exist for the following types of applications.

54. Necessary Parameters for Filter Test Standard
Type and mean size of test particles
Size distribution requirements for the test particles
Method of particle generation
Method of particle detection
Particle Penetration (or Efficiency) range
To have a repeatable Filtration Test Standard you need to have the following parameters:
Type and mean size of test particles
Size distribution requirements for the test particles
Method of particle generation
Method of particle detection
Particle Penetration (or Efficiency) range

55. Many different test methods exist
Summary
Many different test methods exist
Different methods give different results
Correlations are often not practical
Knowing the details of a test method is important if you are trying to compare results from different methods
Many different test methods exist
Different methods give different results
Correlations are often not practical
Knowing the details of a test method is important if you are trying to compare results from different methods
Thank You and are there any questions

56. Contact Information
Tim Johnson Product Specialist - Particle Instruments TSI Incorporated
Use this slide if presenting through the web