Aerosol Photometers: The Gold Standard in HEPA Filtration Testing - PowerPoint PPT Presentation

Loading...

PPT – Aerosol Photometers: The Gold Standard in HEPA Filtration Testing PowerPoint presentation | free to download - id: 6710aa-NmQzN



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

Aerosol Photometers: The Gold Standard in HEPA Filtration Testing

Description:

Title: Slide 1 Author: Carolyn Chapman Last modified by: Tim McDiarmid Created Date: 3/7/2006 4:49:58 PM Document presentation format: On-screen Show (4:3) – PowerPoint PPT presentation

Number of Views:14
Avg rating:3.0/5.0
Slides: 199
Provided by: CarolynC154
Learn more at: http://www.atitest.com
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Aerosol Photometers: The Gold Standard in HEPA Filtration Testing


1
Aerosol Photometers The Gold Standard in HEPA
Filtration Testing
  • Presented by
  • Dave Crosby
  • Tim McDiarmid
  • Don Largent Air Techniques International
  • www.ATItest.com
  • info_at_ATItest.com

2
Introductions
3
Agenda
  • History of Photometry
  • Science of Photometry
  • Applications of Photometry

4
History of Photometers HEPA Filters
5
History of Photometers HEPA Filters
  • You cant have one without the other

6
The photometer was first since there was a need
  • David Sinclair, Ph.D.
  • (Nephelometer)
  • (Not portable and had logarithmic display)

7
Air Pollution Research 1933
8
WW II generated a high priority need
  • It all started in 1942

9
Some Key Players
Wendell Anderson, Humphrey Gilbert, Dr. Melvin
First
10
Captured WW II German Gas Masks
  • The US had performed no gas mask development
    since WW 1
  • German masks used cellulose asbestos media
    patented by Dräger Werke in 1933
  • Wendell Anderson working with HV developed media
    comparable to the German sample

11
M10A1 Canister
12
Tank APC M-25 Mask
13
Smoke Penetrometer to test the gas mask paper
filters
14
First Linear Photometer
15
Space Filter
  • US military needed filtration of room areas for
    people and used gas mask media for a pleated
    filter for larger air flow (1943-1948)
  • Know as Collective Protection
  • Used cardboard spacers between pleats, which had
    high air flow resistance

16
Cardboard Pleat
17
Manhattan Project
  • Humphrey Gilbert safety engineer at Los Alamos
    was sent to Oak Ridge
  • Filters used in Manhattan Project were very thick
    with extremely high pressure drop
  • Foresaw need for high efficiency air filters in
    HVAC systems

18
Absolute Air Filter
  • Gilbert (now with AEC) unhappy with Army Space
    filter and its limitations
  • AEC in 1948 gives Author D. Little a contract to
    redesign filter and find a supplier
  • Walter Smith Ph.D. comes up with corrugated
    cardboard separator idea

19
Improved Pleated Filter Design
20
(No Transcript)
21
HEPA Filter Development
  • First Air Cleaning Seminar for AEC personnel held
    June 1951 at Harvard Air Cleaning Laboratory
  • First Handbook on Air Cleaning distributed at
    meeting
  • Fires at several weapons plants made need for
    high temperature and water resistance necessary

22
Second Air Cleaning Conference held in Ames, IA
1952 Melvin W. First Ph.D. Presented four
research papers
23
  • Military develops procedures and
  • Apparatus to test High Efficiency filters and
    related products
  • Penetrometers
  • Q-127 Low Flow
  • Q-76 Med. Flow
  • Q-107 High Flow
  • Rough Handling
  • Water Repellency
  • etc.

24
HEPA Development for Fire Water Resistance
(1953)
25
First HEPA Guide (1961)
26
Willis Whitfield (1961)
Discovery of Laminar Flow at Sandia National Labs
27
SNL Demonstrates Clean Room Concept in Chicago
for IES(T)
(1962)
28
First In Place Filter Test
29
First Portable Linear Photometer TDA-2 (1962)
30
JM-1000 Photometer (1964)
31
Next Portable Photometer TDA-2A (1964)
Cabinet covered in white Formica (White Rooms)
First Scanning Probe
32
Next Portable Photometer TDA-2B (1965-66)
Ergonomic front panel design
33
First Commercial Standards (1967)
34
First Commercial Standards (1967)
35
Discussion
36
What is a Filter
37
Before Photometry
  • What is a Filter?
  • Filtration Mechanics
  • MPPS
  • How to Test a Filter
  • Efficiency
  • Leak (Integrity)

38
What is a Filter?
  • Separation of one phase from another
  • Solids or liquids in Air (Home Furnace)
  • Solids in liquid (Auto Oil/Gas)
  • Liquid in Air (Air oil separators)
  • Liquid in liquid (RO)
  • Gas in Gas (Activated Carbon)

39
What is a Filter?
  • A Controlled Leak!
  • Filtration controls the amount of impurity that
    is allowed to pass.
  • There is no such thing as a perfect filter
  • (no resistance and 100 efficiency)

40
Filtration Types
  • Materials
  • Fibers
  • Fibrous Structures
  • Micropores
  • Performance
  • High Efficiency
  • Low Efficiency

41
What are we dealing with?
  • Solids or liquids in Air
  • Fibrous Filters
  • Other structures are more common in ultra
    filtration and special applications

42
Fibrous Filters
  • Typically Depth Filters
  • Filtration throughout media depth
  • Very low to very high particle removal
  • Fibrous Filter Construction
  • Filter Disks/Pads
  • Pleated Cartridges
  • Bags/Pockets

43
Filtration Mechanics
  • Pressure Drop
  • Single Filter Efficiency
  • Collection Mechanisms

44
Darcys Law
  •  

?P
45
Darcys Law
  •  

46
Filter Pressure Drop
Pressure Drop
Linear Pressure Drop Inertial Velocity (Darcy
Law) Regime Regime
47
Filtration Assumptions
  • Fibers are in cross flow
  • Particles are collected upon contact with
    fiber
  • Uniform fiber diameter
  • Uniform particle size

48
Single Fiber Efficiency
Air Volume swept out by fiber
  • Single Fiber Efficiency
  • ?s

Particles collected by fiber
. Particles in
volume of air geometrically swept out by fiber
49
Fiber Structure - HEPA
50
Particle Collection Mechanics
  • Sieving
  • Inertial Impaction
  • Diffusion
  • Interception

51
Particle Collection Sieving
Fibers
Particle Flow
52
Particle Collection Interception
53
Particle Collection Inertial Impaction
54
Particle Collection Diffusion
55
Particle Collection Mechanisms
56
High Efficiency Filter MPPS (Most Penetrating
Particle Size)
Penetration
Particle Size
57
Filtration is Selective Particle Collection
Small and big particles are more effectively
collected
58
Impact of Flow Rate on Efficiency
59
Media Velocity is Lower Than Face Velocity
A Filters Performance is Determined at Media
Velocity
60
Consideration in Filter Design
  • Penetration or efficiency
  • Critical Particle Size
  • Pressure Drop or resistance
  • (Cost)

61
Filter Tests
  • Efficiency
  • Media Manufacturer
  • Filter Manufacturer
  • 3rd Party Certification
  • Leak/Integrity
  • Filter Manufacturer
  • Field/In-Situ

62
Efficiency Testing
  • Challenge filter with aerosol at or near the MPPS
  • This requires a mono-dispersed aerosol (tight
    distribution)
  • Measure upstream and downstream concentration
  • Sequential or parallel (simultaneous)
    measurements
  • Efficiency 1 Downstream
  • Upstream
  • Note This is a global measurement (i.e. entire
    filter)

63
Typical Filter Efficiency Test System
Recommended filter performance test system from
IEST RP-CC-0021
64
What is a Leak?
  • Leak is a local measurement.
  • Leak is generally 5 10 times the average
    penetration at a local spot.
  • Therefore we do not require a mono-dispersed
    challenge aerosol at the MPPS
  • Easier and less costly to generate larger
    particles with a broader distribution.

65
A Good Filter Will Allow Few Particles to
Penetrate
66
Add a Leak and
67
Test for a Leak/Integrity
  • Measure local penetration at each sample location
    to determine
  • Filters are not faulty / not been damaged
  • Filters have been installed properly
  • There are no leaks in the mounting frame /
    between mounting frame and housing
  • System contains no by-pass of the filter

68
Leak/Integrity Scanning
Ensure that all parts of filter are within
specification
69
Efficiency vs. Leak/Integrity in General Terms
Efficiency Testing Leak Testing
Global Local

Determine Penetration Yes Yes1
Pinpoint Leaks No Yes

Manufacturer Test Yes Yes2
Field Test No Yes
1 Local penetration, not overall efficiency 2
Due to variations in the media manufacturing
process
70
Discussion
71
When Testing a Filter What are We Looking For?
72
Lets Review
  • Particulate penetration as
  • Efficiency
  • Leak
  • Size of interest?
  • MPPS from 0.08 to 0.18 micron
  • Even when looking for a leak?
  • However..

73
What is a particle?
74
The Simplest Particle?
75
Equivalent Particle Size
  • Diameter of a Sphere that has the same magnitude
    of a chosen Property as the particle In question
  • Optical Diameter (Eye/microscope)
  • Scattering Diameter (Light Scattering)
  • Electric Mobility (Charge On Particle)
  • Mobility (Diffusion)
  • Stokes Diameter (Drag Forces)
  • Aerodynamic Diameter (Settling Speed)

76
In Filtration, Collections of Particles Interest
Us
  • Aerosol Solid/Liquid and Gas (dust, fog)
  • Hydrosol Solid/Liquid and Liquid (milk,
    paint, lotion)
  • Foam Gas in Solid or Liquid (sponge, shampoo)

77
Key Concepts
  • Drag Force proportional dp gt 10µm
  • Slip Correction for dp lt 10µm
  • Stopping Distance and Relaxation Time
  • Settling velocity
  • Mobility and Electric Mobility
  • Diffusion and Brownian Motion
  • Coagulation
  • Dimensionless Numbers

78
Units of Measurement in Filtration
  • µm Micrometer, 10-6 meter
  • Nm Nanometer, 10-9 meter
  • A Angstrom Unit, 10-10 meter
  • 1 µm 1,000 nm 10,000 A
  • Some perspective
  • 1cm is 1000 µm 1in 2.54 cm 25,400 µm

79
Particle Sizes of Interest
Item Approximate Particle Diameter
Eye of a Needle 1,230 microns
Beach Sand 100 2000 microns
Table salt 100 microns
Human hair 40 - 300 microns
Talcum powder 10 microns
Tobacco Smoke 0.01 1.0 microns
Bacteria 0.2 - 0.3 microns
Virus lt0.005 0.05 microns
80
Typical Particle Sizes
0.3um
81
Another Particle Size Chart
82
Typical Settling Velocity
Diameter (um) Feet/min 0.1 0.00016 1.0 0.0
02 10.0 0.59 100 59.2
83
How is an Aerosol Characterized?
Consider this data set
Frequency Frequency
X (range) Raw Data Normalized

0 to 5 100 20

5 to 6 70 70

6 to 8 60 30
84
Normalized Frequency Distribution
Y/?X
85
Size Distribution Terms
  • Independent variable, X
  • Mean Xm
  • Standard Deviation, s
  • Mode (peak)
  • Median (50th percentile)

86
Arithmetic Standard Deviation
87
Geometric Standard Deviation
88
Particle Size Distribution
  • Most Natural Processes are Geometrically
    Distributed and often multi modal
  • Number (count), Surface, or Volume (mass)
    Distribution are common weightings

89
Why is this important?
Due to data weighting the 0.3um DOP particle
measured in the 50s is a volume (mass)
mean whose number (count) median is actually
closer to 0.18umthe MPPS
90
Geometric vs. Arithmetic
  • Consider Geometric as Arithmetic or Linear on a
    log scale
  • Geometric spreads out the lower end
  • In Arithmetic, equal differences result in equal
    spacing
  • In Geometric, equal ratios result in equal spacing

91
Geometric vs. Arithmetic
Equal intervals Arithmetic 2-1.8 1.8-1.6
(equal differences) Geometric 10/7.48
7.48/5.62 (equal ratios)
92
Why Use Log Normal Distributions?
  • No Negative Values
  • For known distributions, the Means of different
    weightings can be calculated from the others
  • For example, Mass (volume) Mean calculated from
    Count (number) mean

93
Number and Volume Weighting
dp Number Counts Volume (pd3/6)
1 1,000,000 523,000
10 100 523,000
100 1 523,000
94
Key Points to Remember
  • Particles come in many shapes and sizes
  • ALL measurements determine some physical property
    and provide an Equivalent Size
  • In filtration, larger particles settle out and
    are not important, particularly cleanrooms
  • Geometric Distributions (aka Log Normal) are used
    to define particle size distributions
  • Mass and Number weightings are common in particle
    measurements

95
Discussion
96
Now we know we are looking for particles The
Light-Particle Interaction
97
Primary Light-Particle Interactions
  • Elastic Scattering
  • Rayleigh Scattering
  • MIE Scattering
  • Phase Shift
  • Polarization
  • Absorbtion

98
LIGHT PARTICLE INTERACTION
99
Common Properties
  • Refraction the apparent change in direction of
    light due to change in refractive index within
    one medium or between dissimilar medium
  • Reflection redirection of light at the surface
    of a material
  • Diffraction bending or deflection of light
    around a particle
  • Polarization oscillations of the light
    occurring in a defined plane

100
Complex Numbers
  • (4)1/2 2
  • What is (-1) 1/2 ?
  • It is defined by the symbol i
  • A complex number is written as (a - b i) where
    the imaginary part is represented by the symbol i

101
Refractive Index
  • Refractive Index of a material is a complex
    number
  • Usually given as 2 - 4i
  • The imaginary part is due to absorption

102
Refractive Index of Common Materials
  • Quartz 1.54 - 0i
  • Glass 1.5 to 1.9 - 0i
  • PSL 1.59 - 0i
  • Ca Sulfate 1.57 - 0i
  • Carbon 2.0 0.33i
  • Iron 1.5 1.63i

103
Refraction
i
r
Refractive Index sine r / sine i
104
Size and Scattering Regimes
Size Range of Interest
105
Elastic Scattering
  • Redirection of Incident Light without change in
    wavelength
  • Refraction internal to particle, wavelength and
    composition dependent
  • Reflection at surface of particle, dependent on
    wavelength and composition
  • Diffraction external to particle, independent
    of wavelength and composition

106
Particle Size Affects Elastic Scattering
  • Optical Particle Size (a) a pd / ? where
  • d particle diameter
  • ? wavelength
  • Scattering Intensity (Is)
  • Is ?2 f(a) where
  • f(a) is a size dependent function

107
Light Scattering
  • Particles much smaller (lt 0.025um) than the
    wavelength of light results in Rayleigh
    Scattering
  • Particles comparable to the wavelength of light
    (0.025gt x lt 2.5um) results in MIE Scattering
  • Much larger particles result in geometric
    scattering.

108
Light Scattering
  • Particles much smaller (lt 0.025um) than the
    wavelength of light results in Rayleigh
    Scattering
  • Particles comparable to the wavelength of light
    (0.025gt x lt 2.5um) results in MIE Scattering
  • Much larger particles result in geometric
    scattering.

109
Rayleigh Scattering
110
Rayleigh Scattering
111
Mie Scattering
Wavelength, ?
Incident light
112
MIE Scattering
113
MIE Scattering
114
Discussion
115
Multiple and Single Particle Sensing and Sensors
116
Multiple Particle Sensing
  • Sampling Volume 1/number concentration
  • Independent of sample volume (measuring a
    cloud)
  • Precision depends on averaging time (due to
    variations in the cloud)

117
Multiple Particle Sensors
  • Extinction (umbrella)
  • Smoke Meter (soot content in exhaust stack)
  • Transmissometer (visual ranging)
  • Scattering
  • Intensity (nephelometry)
  • Backscatter (LIDAR)
  • Photometry

118
Photometer
  • Aerosol is illuminated by a light source
  • Total scattered light is detected by PMT
  • Total concentration is measured

119
Photometer
120
Photometer Focal Point
121
Nephelometer
  • Particle density is a function of the light
    reflected into the detector from the illuminated
    particles

122
Multiple Particle Sensors Summary
  • Light-Particle interaction results in scattering
  • Optical instruments in particle measurement is
    dependent upon the particle size and scattering
    properties
  • Multiple particle scattering is independent of
    volume depends on averaging time.

123
Single Particle Sensing
  • Sample Volume ltlt 1/number concentration
  • Requires a precise, known volume of sampled air
  • Same as counting events precision depends on
    total counts

124
Single Particle Sensors
  • Light attenuation (extinction)
  • Scattering (Particle Counters)
  • Laser
  • White Light
  • Angular Scattering
  • Doppler anemometer

125
Particle Counter
O
O
Electronics
126
Common Particle Counter Challenges
  • Multi Valued Response
  • Coincidence
  • Problems at small particle sizes

127
Multi Valued Signal
128
Coincidence
O
O
Electronics
129
Small Particle Detection
  • Scattering intensity is very small
  • Common Solutions
  • Increase intensity of light
  • Change light source wavelength
  • New techniques?

130
Small Particle Detection
  • Increase Intensity
  • Improves signal from particles
  • Increases noise from air molecules
  • Reduce the wavelength
  • Shifts the curves to smaller sizes
  • Increases noise from molecules
  • Reduce the viewing volume

131
Condensation Nucleus Counter
Alcohol
132
Single Particle Sensors Summary
  • Most optical measurements are in the MIE regime
  • Single particle counting requires known volume of
    sampled air
  • Same as counting events precision depends on
    total counts long sample times at low counts
  • Problems of coincidence at high concentrations
  • Non unique response and low signal to noise ratio
    at small sizes
  • Small sizes handled by using smaller wavelengths
    or proprietary methods

133
Photometer vs. Particle Counter vs. CNC
  • Photometer
  • Measures Total Aerosol
  • Response Linear With Total Aerosol Volume
  • Requires Known Aerosol And Relatively High
    Concentration
  • Problems
  • No Particle Size Information
  • Requires High Concentrations

134
Photometer vs. Particle Counter vs. CNC
  • Particle Counter (Laser)
  • Detects and sizes particles
  • Counts by size
  • Measures down to 0.1 µm
  • Can use any aerosol
  • Problems
  • Assumes everything measured is a PSL
  • Multi Valued Response
  • Coincidence
  • Problems at small particle sizes
  • Long sample times to obtain a statistically valid
    results

135
Photometer vs. Particle Counter vs. CNC
  • CNC
  • Particle detector only
  • Can measure less than 0.05 µm
  • Problems
  • Requires mono-dispersed aerosol
  • Counts all particles, noise at bottom end
  • Long sample times to obtain a statistically valid
    results

136
Discussion
137
Aerosols and Aerosol Generators
138
What is a Standard?
  • A KNOWN and Universally Accepted value of a
    physical property or quantity
  • Meter for measure of length
  • ?C for Temperature

139
Why are Standards Necessary?
  • They establish accuracy of measuring instruments
  • Calibrate the accuracy of instruments in use
  • Temperature
  • Scales
  • Flow Meters
  • Photometers
  • Particle Counters

140
How Does this Affect Aerosols?
  • A Standard Aerosol has KNOWN properties
  • Particle Size and Distribution
  • Concentration
  • Shape (usually spherical)
  • Chemistry (inert)
  • And Refractive Index in our business

141
Aerosol Standards
  • Mono-disperse Aerosol
  • Single size particles sg 1.4
  • Instrument Calibration for PCs
  • Research Development
  • Near Mono-disperse Aerosol
  • Narrow distribution 1.4 lt sg 1.6
  • Some Production QC Level of accuracy
  • Poly-disperse Aerosol
  • Broad distribution 1.6 lt sg
  • Industrial measurements
  • Instrument verification
  • Some instrument calibrations

142
Mono vs Poly Disperse
143
Mono vs Poly Disperse
144
Implication on Size Dispersion
  • For a log normal distribution
  • 95 of the particles are between
  • Mean sg2
  • sg2 Mean

145
Implication on Size Dispersion
  • An aerosol with mean of 0.3um
  • sg 1.2
  • 95 of particles are between 0.21 0.43um
  • sg 2.0
  • 95 of particles are between 0.075 and 1.2um

146
Mono vs Poly Disperse
147
Three Types of Aerosol
  • Mono-disperse sg 1.4
  • Near Mono-disperse 1.4 lt sg 1.6
  • Poly-disperse 1.6 lt sg

148
Typical Poly-Disperse Aerosol Standards
  • Laskin Nozzle
  • Wright Nebulizer
  • Pneumatic Nebulizer
  • Condensation Generators
  • Spinning Disk
  • Exploding Wire
  • Standard Dusts

149
Laskin Nozzle
150
Laskin Nozzle
151
Laskin Nozzle
152
Laskin Nozzle Concentration Calculations
  • Output of Laskin Nozzle is defined
  • By Nozzles _at_ 20 PSIG Concentration
    Nozzles x 13,500
  • Total Flow (cfm)
  • By Jets at 20 PSIG
  • Concentration Nozzles x 3,375
  • Total Flow (cfm)
  • Note there are 4 jets in a standard Laskin
    Nozzle

153
Laskin Nozzle Concentration Calculations
  • You can calculate the system concentration, if
    you know
  • System Air Volume (CFM)
  • Number of Laskin Nozzles/Jets at 20 PSIG
  • You can calculate the number of nozzles/Jets, if
    you know
  • System Air Volume (CFM)
  • Desired system concentration

154
Wright Nebulizer
155
Pneumatic Nebulizer
Liquid
156
Thermal Condensation Aerosol Generators
Heater
Quench Air
157
Thermal Aerosol Generator
  • Polydispersed
  • Produces a greater level of aerosol concentration
    than pneumatic type nozzle
  • Applications include higher flow systems
  • Median particle size is smaller than pneumatic
    generation
  • Output concentration cannot be calculated as
    output is variable
  • Size and distribution shift with concentration

158
Ultrasonic Nebulizer
159
Spinning Disk Particle Generator
160
Exploding Wire
161
Test Dusts
  • Standard Dust (Arizona Road Dust)
  • Mainly Silica with
  • Mass Mean Diameter of 7 µm
  • sg of 3.6
  • Specific Gravity of 2.7
  • Originally collected from Arizona Desert

162
Test Dusts
  • ASHRAE
  • Custom blend of
  • 72 ISO 12103-1, A2 Fine Test Dust,
  • 23 powdered carbon
  • 5 milled cotton linters
  • Attempt to simulate natural dust for HVAC

163
Test Dusts
  • SAE Dusts automotive filter testing
  • Fine
  • Mass Median Diameter 25µm
  • No particles gt 100µm
  • Coarse
  • Mass Median Diameter 60µm
  • 10 may be larger than 100µm

164
Common Mono-disperse Aerosol Standards
  • Poly Styrene Latex (PSL)
  • Vibrating Orifice
  • Electrostatic Classification
  • Condensation Techniques

165
PSL Aerosols
  • NIST Traceable PSL Particles
  • Examples
  • Methodology
  • Atomize PSL in Liquid (water)
  • Evaporate the liquid
  • NIST Traceable PSL Aerosol

166
PSL Aerosols
167
Residue PSL Aerosols
  • Impurities in water become small particles
  • These particles can be counted as particles in
    standard aerosol, especially by a CNC

168
Residue PSL Aerosols
  • Assuming a typical 2um atomizer droplet and 10
    ppm purity water,
  • Residue particle size can be computed
  • 10 x 10-6 (residue dia/drop dia)3
  • Residue Diameter 0.04um

169
Residue Particles
170
PSL Aerosols
  • Common for Cleanroom Applications
  • NIST traceable PSLs are expensive
  • PSLs are easy to aerosolize, but output
    concentration is variable
  • Limited by residue at small sizes
  • Not available in large sizes
  • PSL gives excellent optical response
  • Used as calibration aerosol for particle counters

171
Electric Mobility Classification
172
Points to Remember
  • Standards are required to verify and calibrate
    instruments and devices
  • A Standard aerosol can be either poly or mono
    disperse
  • RD standards are more precise and are for
    laboratory use
  • Industrial standards are easier to produce and
    are widely used

173
Points to Remember contd.
  • Poly-disperse aerosols are commonly generated by
    atomization, nebulization or mechanical means
  • Only a few techniques are available to generate
    very tight, mono-disperse aerosols
  • NIST traceable PSLs are generated in small
    quantities and are very expensive
  • PSL concentration output is variable
  • Residue particles can be a problem in small sizes

174
Discussion
175
Photometer Testing Standards Practices
176
What is a Filter Testing Standard?
  • A DOCUMENTED and Universally Accepted method of
    obtaining a Qualitative Performance Measurement

177
Why are Standards Necessary?
  • They establish consistent methodology
  • Provide a guide for understanding and
    compensating for variables encountered during
    practical application

178
How Does this Affect Filter Testing?
  • A Test Standard defines methods and limits
  • Aerosol characteristics
  • System Operating Conditions
  • Testing protocols
  • Allowable Challenge Concentrations
  • Sampling Rate
  • Maximum Allowable Leakage
  • Scanning Speed

179
Standards Recommended Practices Organizations
  • AACC (American Association for Contamination
    Control)
  • ISO (International Organization for
    Standardization)
  • BNL (Brookhaven National Laboratory)
  • ASTM (American Society for Testing and Materials)
  • EN (European Norm)
  • IEST (Institute of Environmental Science
    Technology)
  • ANSI (American National Standards Institute)
  • ASME (American Society of Mechanical Engineers)
  • DOE (Department of Energy)

180
Filter Testing Standards
  • CS-IT (1968) Standard for HEPA filters
  • CS-2T (1968) Standard for Laminar Flow Clean Air
    Devices - Installation Leak Test (filter and
    gaskets)
  • CS-2T (1968) Standard for Laminar Flow Clean Air
    Devices - Induction Leak Test (seams and joints)
  • 14644-3 (2005) Cleanrooms Associated
    Environments, Annex B- Test Methods (Informative)
  • IH62300 (2001) In-Place HEPA Filter testing,
    Section 6.2 Equipment
  • EN-1822-2 High Efficiency Air Filters (HEPA
    ULPA)-Part 2 Aerosol Production, Measuring
    Equipment, Particle Counting Statistics
  • IES-RP-CC001 HEPA ULPA Filters
  • IES-RP-CC006 Testing Cleanrooms
  • IES-RP-CC007 Testing ULPA Filters
  • IES-RP-CC034 HEPA ULPA Filter Leak Tests
  • Fed Std 209E (1992 by IEST) Most referenced in
    Filter industry was replaced by ISO 14644-1 2
    in November 2001
  • NSF 492008 (Annex A2008) Biosafety Cabinetry
    Design, Construction, Performance Field
    Certification-Performance Tests
  • NSF 492008 (Annex F2008) Biosafety Cabinetry
    Design, Construction, Performance Field
    Certification-Field Tests
  • ASME N509 (2008) Nuclear Power Plant Air-Cleaning
    Units Components)
  • N510 (2007) Testing of Nuclear Air Treatment
    Systems
  • N511 (2007) In-Service Testing of Nuclear Air
    Treatment Heating, Ventilating and
    Air-Conditioning Systems
  • DOE-HDBK-1169, DOE Handbook Nuclear Air Cleaning
    Handbook, Section 8.6.1 In-Place Testing

181
Industries Using Photometry
  • Pharmaceutical
  • Non-pharmaceutical
  • Civilian
  • Nuclear Power
  • Military
  • Nuclear Weapons
  • Chemical Weapons
  • Biological Weapons

182
Photometer vs. Discrete Particle Counter
  • 1968 CS-1T Standard for HEPA Filters
  • Particle Counter
  • No defined method
  • Photometer
  • Upstream challenge aerosol must be at least
    27ug/l
  • Maximum Leakage 0.01
  • Scanning rate 2 inches per second _at_ 1 inch from
    filter face

183
Photometer vs. Discrete Particle Counter
  • 1968 CS-2T Standard for Laminar Flow Clean Air
    Devices
  • Installation Leak Test (for filter gaskets)
  • Particle Counter
  • No defined method
  • Photometer
  • Upstream challenge aerosol must be at least
    27ug/l
  • Maximum Leakage 0.01
  • Scanning rate 2 inches per second _at_ 1 inch from
    filter face

184
Photometer vs. Discrete Particle Counter
  • 1968 CS-2T Standard for Laminar Flow Clean Air
    Devices
  • Induction Leak Test (for seams joints)
  • Particle Counter
  • Ambient aerosol must be gt300K particles/ft3
  • Maximum leakage gt100 counts
  • Scanning rate 2 inches per second _at_ 1 inch from
    joint or seam within clean zone
  • Photometer
  • Ambient aerosol must be at least 10 E3 above FF
  • Maximum Leakage gtFF
  • Scanning rate 2 inches per second _at_ 1 inch from
    joint or seam within clean zone

185
Photometer vs. Discrete Particle Counter
  • 2005 ISO 14644-3 Cleanrooms associated
    controlled environments, Test methods
  • Installed Filter System Leakage
  • Photometer
  • Upstream challenge aerosol of between 20 80ug/l
  • Maximum Leakage 0.01
  • Scanning rate 2 inches per second _at_ 1 inch from
    filter face
  • Limitations
  • Efficiency lt 99.997 _at_ MPPS
  • Oil aerosols allowed
  • Ability to achieve required concentrations
  • Particle Counter
  • Upstream challenge aerosol (Too much detail to
    list here _at_ 6 pages) sufficiently high that Np gt2
    lt10
  • Maximum leakage 0.01
  • Scanning rate 3.14 inches per second (varies
    depending on probe dimensions, Np, sample rate

186
Photometer vs. Discrete Particle Counter
  • 2005 ISO 14644-3 Cleanrooms associated
    controlled environments, Test methods
  • Containment Test
  • Photometer
  • Upstream challenge aerosol of between 20 80
    ug/l
  • Maximum Leakage 0.01
  • Scanning rate 2 inches per second at 2 inches
    from joint, seal or mating surfaces
  • Limitations
  • Efficiency lt 99.997 _at_ MPPS
  • Oil aerosols allowed
  • Ability to achieve required concentrations
  • Particle Counter
  • The greater of
  • ambient count X E103
  • gt 3.5 E106 particles/m3
  • Maximum leakage ambient count X E10-2
  • Scanning rate 2 inches per second at 2 inches
    from joint, seal or mating surfaces

187
Photometer vs. Discrete Particle Counter
  • 2001 IH623002001 In-Place HEPA Filter testing
  • Photometer
  • Upstream challenge aerosol 104 greater than
    ambient
  • Maximum Leakage 0.03
  • Duct measurement-No scan
  • Particle Counter
  • No defined method

188
Photometer vs. Discrete Particle Counter
  • IEST-RP-CC006 Testing Cleanrooms
  • Photometer
  • Upstream challenge aerosol of between 10 to 20
    ug/l
  • Maximum Leakage 0.01
  • Scanning rate 2 inches per second _at_ 1 inch from
    filter face
  • Particle Counter
  • 3 x E108 /m3 _at_ particle size of interest (10
    counts per Appendix B, Exp. 1)
  • Maximum Leakage 0.01
  • Scanning rate
  • (Cc)(Ls)(Fs)(Dp) (60)(Np)
  • Result 3.3 ft/min _at_ 1 in or 0.65
    inches per second
    (Appendix B, Exp. 1)

189
Photometer vs. Discrete Particle Counter
  • IEST-RP-CC034 HEPA ULPA Filter Leak Tests
  • Photometer
  • Upstream challenge aerosol of between 10 to 90
    ug/l
  • Maximum Leakage 0.01
  • Scanning rate 2 inches per second _at_ 1 inch from
    filter face
  • Particle Counter
  • 2.8 x E108 /m3 _at_ particle size of interest (10
    counts per Appendix G, Exp. 1)
  • Maximum Leakage 0.01
  • Scanning rate (2.8)(108)1000(0.0001)
    (28.3)(1.25)(60)(10)
  • Result 1.25 cm/s _at_ 1 in or 0.5 in/sec
  • (Appendix G, Exp. 1)

190
Photometer vs. Discrete Particle Counter
  • 2008 NSF 49 Biosafety Cabinetry
  • Photometer
  • Upstream challenge aerosol of at least 10 ug/l
  • Maximum Leakage 0.01
  • Scanning rate 2 inches per second _at_ 1 inch from
    filter face
  • Particle Counter
  • No defined method

191
Points to Remember!
  • Photometer particle counter results are not
    likely to correlate due to the different
    weighting of the technology used.
  • Photometry response is mass weighted while
    particle response is number weighted.
  • Filter testing process is the same regardless of
    photometer or particle counter use.
  • Measure upstream challenge
  • Measure downstream penetration by scanning or
    point sampling
  • Calculate penetration

192
Points to Remember!
  • Filter testing process complexity varies between
    photometers and particle counters.
  • Challenge concentration
  • Photometers Variable range of 10-100 ug/l with
    10-30 ug/l being typical (Std defined)
  • Particle counters Variable range of 3.0 E105 to
    3.0 E108 (Std defined, calculated to achieve
    desired Np)
  • Measure Downstream
  • Photometers 0.01 leakage maximum while
    scanning rate of 2 inches /second in most cases
    (Std defined)
  • Particle counter 0.01 leakage maximum in most
    cases while scanning at a calculated,
    statistically, determined rate (Std defined)

193
Points to Remember!
  • Calculate Penetration
  • Photometer Ratio of upstream challenge to
    downstream expressed as a percent
  • Particle counter Ratio of upstream challenge to
    downstream expressed as a percent

194
Points to Remember!
  • Each technology has design strengths and
    weaknesses which decide where its use is
    reasonable in filter leakage testing.
  • Photometer
  • Aerosol generator for upstream challenge oil
    aerosol
  • No diluter necessary for Upstream measurements
  • Consistent essentially Calculation Free test
    method
  • Limited to systems with efficiencies 99.997
  • Typically consistent results among multiple units
  • Robust core technology
  • Particle counter
  • Aerosol generator required in most cases, but at
    a lower output
  • Use of solid or liquid aerosol possible
  • Ability to test systems to 99.9999 efficiency
  • Diluter required for upstream sampling
  • Unit to unit result consistency difficult to
    achieve
  • More sensitive detection system results in
    less-robust instrument

195
Discussion
196
Hands On Demo Photometer Filter Leak Scanning
197
Review and Discussion
198
Thank you
Your logo here. Important Logo only on FIRST and
LAST slides.
  • David W. Crosby
  • Tim McDiarmid
  • Don Largent
About PowerShow.com