real time aerosol measurements

© 2008, TSI Incorporated

Real Time Aerosol MeasurementsReal Time Aerosol Measurements

Gregory M. Olson, Jr., M.S. Gregory M. Olson, Jr., M.S.

Sr. Industrial HygienistSr. Industrial Hygienist

Product Manager - Health and SafetyProduct Manager - Health and Safety

TSI IncorporatedTSI Incorporated

[email protected]@tsi.com


Agenda

• Global and Regional Monitoring Trends• Monitoring Segments and Applications• New Measurements and Instruments

– The Measurements• How they work • What they measure• Theory of Operation

– New Features

• Direct Reading Technology Comparisons• Questions


Monitoring Trends

• Real time aerosol sampling instruments have not changed significantly in the last decade

• Real time aerosol monitoring is growing in interest and acceptance, becoming industry best practices– It still does not meet reference method equivalency

• Worldwide regulatory agencies have shown considerable interested in benefits of using real time monitoring in addition to compliance monitoring

• Environmental Health & Safety (EH&S) industries have also shown great interest in and acceptance of real time aerosol monitoring – It is becoming an industry best practice and the preferred

method of monitoring in these market segments


Monitoring Trends

• Additional and new outdoor air quality regulations in Australia, China, Singapore, Hong Kong, and other Asian countries– Need to measure multiple size fraction simultaneously for

mass, for example• PM10 and PM2.5

• Total PM and PM10

• For industrial hygiene and indoor air quality applications– Also, want to measure multiple size fractions for mass at the

same time• Total PM, PM10(thoracic), and respirable > Industrial Hygiene• Total PM, PM10 and PM2.5 > Indoor Air Quality


Monitoring Trends

• International markets are growing as a result of:– Additional competitive pressures– Consolidation of standards and best practices,

especially with global companies– Increased interest in environmental, health and

safety issues worldwide

• The number of industrial hygiene and safety professionals is stable in the US and Europe– Growing in Asia, Eastern Europe, Middle East,

BRIC Countries, and Latin America


Monitoring Segments and Applications• Industrial/occupational hygiene

surveys– Baseline trending and screening– Point source monitoring– Engineering control evaluations– HVAC evaluations

• Indoor air quality investigations– Baseline trending and screening– Point source monitoring– HVAC evaluations

• Environmental (non-regulatory) monitoring– Fugitive emissions– Site perimeter– Fenceline– Dust control operations– Environmental research studies

• Process monitoring– Mining industry– Metal working/machining fluid

monitoring inside enclosures– Paper mills– Grain mills– Foundry process monitoring– Paint spray booths– Paint stripping processes

• Engineering studies• Remote monitoring• Emissions monitoring

– Combustion aerosol monitoring with and without dilution tunnels

• Aerosol research studies


DustTrak II and DRX Product Line, Features, and Theory of Operation


Introduction

• To develop of a range of aerosol mass sampling instruments and an environmental sampling platform (ESP) to address 4 major monitoring applications: – Industrial Hygiene– Indoor Air Quality– Environmental (non-regulatory)

• Fugitive Emissions Monitoring– Site Perimeter Monitoring– Fenceline Monitoring

• Dust Control Monitoring– Process Monitoring

Based on customer feedback and market trends


Product Line – DustTrak II and DRX Aerosol Monitors• Five new instruments have been developed

– DustTrak II Model 8530 – basic single-channel (mass only) desk top aerosol monitor for IH/ENV/IAQ applications, replacement for the existing DustTrak

– DustTrak II HC Model 8531 – basic high concentration (400 mg/m3) single-channel (mass only) desk top for Process Monitoring applications

– DustTrak II Model 8532 – basic single-channel (mass only) handheld aerosol monitor for IH/IAQ surveys and point source location applications

– DustTrak DRX Model 8533 – advanced multi-channel (mass/size fraction) desk top aerosol monitor for IH/ENV/IAQ applications

– DustTrak DRX Model 8534 – advanced multi-channel (mass/size fraction) handheld aerosol monitor for IH/IAQ surveys and point source location applications


DustTrak II – the measurement

• DustTrak II aerosol monitors are continuous real-time, single-channel 90° light-scattering laser photometer

• Particle detection range: 0.1 – 10 µm• Desktop and handheld models• Incorporates sheath air system• Internal pump allows the use of inlet conditioners to

measure aerosols corresponding to:– New impactors: PM10, PM4, PM2.5, and PM1.0

– Cyclone: 10 mm Dorr-Oliver Cyclone

• Measure any aerosol contaminant– Dust, smoke, fume, mist, etc.


DustTrak DRX – the measurement

• DustTrak DRX aerosol monitors are advanced continuous real-time, 90° light-scattering laser photometer that simultaneously measure mass and size fraction – No other monitor can do both!

• Desktop and handheld monitors measure size-segregated mass fraction concentration – Total PM, PM10, Respirable, PM2.5, and PM1.0 size fractions

– Over a wide concentration range, 0.001 – 150 mg/m3



• The DustTrak™ DRX Aerosol Monitors patent pending technology method combines both particle cloud and single particle detection to achieve size-segregated mass fraction measurements– It is not an optical particle counter (OPC), it is a photometer!– The DRX effectively combines both measurements in one

instrument– We will talk more about this later (in the Theory of Operation)

• The DRX size-segregated mass fraction measurement is superior to either a basic photometer or an OPC– The DRX delivers the mass concentration of a photometer with the

size resolution on an OPC– We will talk more about this later (TEOM, OPC, and photometer

comparison)



• The DRX can be set to display any of the following size fraction modes– IH Mode: Total PM, PM10, Respirable (≤4 µm) size fractions– ENV/IAQ Mode: Total PM, PM10, PM2.5, PM1.0 – All Mode: Total PM, PM10, Respirable, PM2.5, PM1.0

• Particle detection range: 0.1 - ~15 µm • Incorporates sheath air system• Internal pump for active sampling• No need for inlet conditioners• Measure any aerosol contaminant as long as it is in

the particle detection range– Dust, smoke, fume, mist, etc.


Desk Top Design• DustTrak II Model 8530• DustTrak II HC Model 8531• DustTrak DRX Model 8533


Desktop Models

• Ideal for long-term surveys and remote monitoring applications– Manual and program log modes makes unattended

operation easy– Long run times, up to 12 hours with internal Li-Ion batteries,

and even longer when used in the environmental sampling platform

– Turn it on, set it up, and walk away• A variety of communications allows remote access to

logged data– Ethernet, USB (device) with wireless radio modem, and

analog/alarm output• Instantaneous and 15-minute STEL alarms for many

different applications


Handheld Design

• DustTrak II Model 8532• DustTrak DRX Model 8534


Handheld Models

• Perfect for walk-through surveys and single-data point collection applications

• Lightweight and portable• Ideal for IH surveys, point source location

monitoring, IAQ investigations, engineering control evaluations/validation, and baseline trending and screening

• They have single-point, manual, and program log modes making them very versatile in a wide variety of investigative applications


Gravimetric Reference Sampling

• All desktop instruments have gravimetric sampling capability and active flow control

• To improve accuracy of the photometric measurement, the instrument can be calibrated with gravimetric samples– Typically, conduct side by side photometric to gravimetric samples

• A 37 mm filter cassette (user supplied) can be inserted in-line with the aerosol stream at the outlet of the optical chamber without the need for an external sampling system– Filter must be pre- and post-weighed in a laboratory on a microbalance – User must conduct pre- and post-flowrate calibration, record runtime,

calculate liters of air sampled and provide analytical laboratory with this information

– TSI does not supply any filter media for this type of sampling– It is always best to work with an AIHA/agency accredited laboratory


Auto Zero Module

• All desktop instruments have the ability to be auto zeroed using the optional Auto Zero Module

• When sampling over extended periods of time zero drift occurs

• Zero drift occurs when electronics and mechanical components cause a concentration shift– Even when the DustTrak is connected to a HEPA filter

• This drift is eliminated by re-zeroing the DustTrak electronics with a HEPA filter as often as possible– The optics are purged with HEPA air– Baseline voltage is recorded and becomes the new zero

concentration from which all other concentrations are determined


Auto Zero Module


15-Minute STEL Alarm

• All desktop instruments have the STEL Alarm function to track 15-minute average mass concentrations exceeding the alarm setpoint

• STEL Alarm can only be enabled when logging data – Logs a separate 15-minute STEL average file based on a 1-

minute log interval

• A visual indication shown on the DustTrak screen as well as an audible warning

• There is a relay switch for the alarm output


DustTrak DRX – Standard and Advanced Calibration Capability

• The DustTrak DRX has two calibration factors– Photometric calibration factor (PCF)– Size calibration factor (SCF)

• PCF shows the photometric response difference between A1 Test Dust and the aerosol being measured

• The SCF accounts for the size difference


DustTrak DRX – Standard and Advanced Calibration CapabilityStandard Calibration• The primary goal of the standard calibration is to obtain the

SCF for the aerosol of interest• This calibration is very easy and does not require a

comparison to gravimetric samples• Measure with and without a PM2.5 impactor

– The ratio of these two size distributions is automatically calculated– This ratio is compared to PM2.5 impactor transmission efficiency curve to

calculate the SCF

• The absolute mass concentration may not be as accurate as the advanced calibration– However, it is better than the original A1 Test Dust Factory Calibration

Factor as it is now size corrected to the aerosol being measured


DustTrak DRX – Standard and Advanced Calibration Capability

Advanced Calibration

• The advanced calibration yields a high size segregated mass concentration accuracy corresponding to– PM10, Respirable, PM2.5, PM1.0 size fractions

• Two separate gravimetric measurements are taken to obtain PCF and SCF


DustTrak DRX – Standard and Advanced Calibration CapabilityAdvanced Calibration• First, take an external PM2.5 gravimetric measurement side by side with the

DustTrak DRX, do not use a PM2.5 impactor on the DRX• PCF2.5 is calculated as the ratio of the PM2.5 gravimetric measurement /

PM2.5 DRX averaged measurement• Second, repeat the same side by side measurements using PM10 impactor

for gravimetric sampling, no impactor on the DRX • PCF10 is calculated as the ratio of the PM10 gravimetric measurement to the

PM10 DRX averaged measurement using the following formula:

• The SCF is calculated using the following formula:


DustTrak DRX – Standard and Advanced Calibration CapabilityAdvanced Calibration (continued)• The advanced calibration is similar to what you do now to

develop a custom calibration factor by conducting side by side comparisons of gravimetric samples to photometric samples– However, you will measure two size fractions in this comparison using an

external sampler to the DRX• Note: do not put an inlet conditioner on the DRX during these measurements

– As always it is recommended to take multiple samples to obtain statistically valid/reasonable mass averages

• The advanced calibration is for advanced users and will accurately measure size segregated mass fraction concentrations

• Additional information is in the DustTrak DRX User Guides and forthcoming in an Application Note


New Impactors

• TSI has designed four new impactors for the DustTrak II and DRX– DustTrak II uses: PM10, PM4, PM2.5, and PM1.0 impactors for size

selective sampling

– DustTrak DRX uses: PM2.5 impactor for Standard Calibration

• All impactors are designed for their specified cut point at a constant flow rate of 3.0 lpm

• They are single-stage impactors– Collection plate is larger than before and made of sintered metal– Use vacuum pump oil, instead of vacuum or Krytox™ grease


New Impactors

• Vacuum oil is preferred over grease, since a greased plate will only last a short time before particle bounce starts to impair impactor performance

• Oil wets the sintered metal surface and the deposited particles due to capillary effect

• Even after the plate is coated with particles, incoming particles will still contact a wet surface, significantly reducing particle bounce

• Oil saturated impaction plate allows much larger mass loading and longer sampling times than a greased plate

• For additional information on the new TSI DustTrak II and DRX impactors see, Application Note EXPMN-003, Impactor Penetration Efficiency Curves


Wireless Modems

• Provides two-way communications between desktop versions of the DustTrak II and DRX and a PC using TrakPro Data Analysis Software– Set up and program DustTrak II and DRX– Retrieval of logged data files remotely (data acquisition)

• USB Radio Modems – line of sight– 922 MHz: indoor/urban up to 1500 ft / 450 m, dipole antenna

outdoor up to 7 mi / 11 km, dipole antenna outdoor up to 20 mi / 32 km, high gain antenna

– 2.4 GHz: indoor/urban up to 600 ft / 180 m, dipole antenna outdoor up to 3 mi / 5 km, dipole antenna outdoor up to 10 mi / 16 km, high gain antenna


Wireless Modems

• Use the radio modems– In the new Environmental Enclosure Model 8535– Attached directly to the DustTrak II and DRX

• Need to supply AC power directly to the radio modems


DustTrak II Theory of Operation


DustTrak DRX Theory of Operation

PhotoDetector

Laser Diode

Light Trap

Aerosol Inlet

Sheath Air

Exhaust

Mirror

Aerosol Measurement

Flowmeter

Gravimetric Filter

Pump

ProtectionFilter

Beam ShapingOptics

Viewing Volume Photometric

Voltage

Single Particle Pulses

Size SegregatedMass Concentration

(eg. PM1, PM2.5, PM4 & PM10)

OpticsChamber

Signal Acquisition and Processing

Orifice

HEPA Filter

Dampening Chamber

LaserBeam


Direct Reading Aerosol Measurement - Technology Comparisons


DustTrak DRX Vs. Other Aerosol Measurement Technologies

• The DRX size-segregated mass fraction measurement technology – Superior to either a basic photometer or optical particle counter

(OPC)– Delivers the mass concentration of a photometer and the size

resolution of an OPC

• Some facts about photometers– Can be used at high concentration, however they do not give

any size information • Unless used with inlet conditioners

– Significantly underestimate large particle mass concentrations


DustTrak DRX Vs. Other Aerosol Measurement Technologies

• Some facts about OPC’s– Provide size and count information – Do not provide any mass information– Do not provide real time information

• Counts are either cumulative or differential in bins• Information is not available until conclusion of test, then it has

to be converted to mass later via software

– Cannot be used in high concentration environments, dependent on particle size distribution

• Example: 4 µm (respirable) particles at a max. concentration of 2 x 106 pt/ft3 = 6.2 mg/m3 (max. concentration for OPC)


DustTrak DRX Advantages Over OPC’s

1. Simultaneous measurement of size-segregated mass fraction concentrations

2. Size-segregated mass fraction data shown in real time

3. Can be used in high mass concentration environments

4. Ability to generate custom calibration factors using standard or advanced calibrations

5. Significantly reduces mass conversion errors using particle size and count data due to particle density, refractive index, and shape

6. Lower particle detection size range down to 0.1 µm


DustTrak DRX Advantages Over Single-Channel Photometers

1. Greater sensitivity to particles >1 µm in size

2. Simultaneous measurement of size-segregated mass fractions

3. Size-segregated mass fraction data shown in real time

4. Ability to generate custom calibration factors using standard or advanced calibrations

5. No need for multiple instruments for different size fraction measurments

6. No need for size-selective inlet conditioners


DustTrak DRX vs. TEOM – A1 Test Dust Mass Concentration Comparison

• Compared the mass concentration readings between DustTrak DRX and a Tapered Element Oscillating Microbalance (TEOM)

• Lab generated aerosol using a TSI Fluidized Bed Aerosol Generator (Model 3400A)

• Mixing chamber used to distribute the aerosol to both DRX and TEOM

• Mass concentration was varied by changing the output of the fluidized bed and dilution air flow rate



• A series of mass concentration tests were run for PM10, Respirable (≤4 µm), and PM2.5

• Since the DRX is capable of measuring all fractions simultaneously, all fractions are plotted on the same graph

• Each graph is a mass concentration comparison of the DustTrak DRX and the TEOM fitted with a specific size-selective inlet



• These graphs show that each size segregated mass fraction measured by the DustTrak DRX shows very good agreement with the TEOM with the appropriate size-selective inlet

• On average the DRX has a response time the is ~8 seconds faster than the TEOM Time

15:26 15:31 15:36 15:41

Mas

s co

nce

ntr

atio

n (

mg

/m3 )

0.1

1

10

100

TEOM-PM10DRX-PM10DRX-PM1DRX-PM2.5DRX-PM4DRX-TPM

PM10



Time

14:44 14:49 14:54 14:59 15:04

Mas

s co

nce

ntr

atio

n (

mg

/m3 )

1

10

TEOM-PM4DRX-PM4DRX-PM1DRX-PM2.5DRX-PM10DRX-TPM

PM4

Time

14:31 14:36 14:41

Mas

s co

ncen

trat

ion

(mg/

m3 )

1

10

TEOM-PM2.5DRX-PM2.5DRX-PM1DRX-PM4DRX-PM10DRX-TPM

PM2.5



• The figures show the linear correlation between the DRX and the TEOM

• It shows the individual size-segregated mass fractions are highly correlated with the TEOM over a wide range of aerosol mass concentrations

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100

TEOM (mg/m3)

DR

X (

mg

/m3 )

PM10y = 0.9855x

R2 = 0.9879

1:1 Line



0

2

4

6

8

10

0 2 4 6 8 10

TEOM (mg/m3)

DR

X (

mg

/m3 )

Respirabley = 0.826x

R2 = 0.9923

0

2

4

6

8

10

0 2 4 6 8 10

TEOM (mg/m3)

DR

X (

mg

/m3 )

PM2.5y = 1.0865x

R2 = 0.9719



Conclusion

• The DustTrak DRX can simultaneously measure multiple size-segregated mass fractions without the need for size-selective inlets

• Has a faster response time

• The DustTrak DRX has a high correlation with a standard reference equivalent method like the TEOM, which is widely used for environmental monitoring


DustTrak DRX Advantages Over TEOM1. Faster response time2. Continuous and faster data acquisition rate (once per second)3. Simultaneous measurement of size-segregated mass fraction

concentrations4. Size-segregated mass fraction data shown in real time5. No need for multiple instruments for different size fraction

measurements6. No need for size-selective inlet conditioners7. No consumables and low maintenance8. Much lower cost of ownership – one instrument can do the

work of many!


Questions?


Thank-You!

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