Personal Ozone Monitor Manual Rev. E-2
i
Personal Ozone Monitor™
2B Technologies, Inc.
OPERATION MANUAL
Model POM™
© Copyright 2016, 2B Technologies, Inc.
All rights reserved.
Technical Support:
www.twobtech.com/techsupport
techsupport@twobtech.com
+1(303)273-0559
Personal Ozone Monitor Manual Rev. E-2
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Contents
IDENTIFICATION RECORDS iv
PRINTING HISTORY v
WARRANTY STATEMENT vi
WARNINGS viii
1. PERSONAL OZONE MONITOR INTRODUCTION 1
1.1. Theory of Operation ................................................................................................................. 1
1.2. Adaptive Filter .......................................................................................................................... 4
2. SPECIFICATIONS 5
2.1. Overview .................................................................................................................................. 5
2.2. Table of Specifications: Personal Ozone Monitor (PAM) ........................................................ 6
3. OPERATION 7
3.1. Shipping Box Contents ............................................................................................................ 7
3.2. Operation of the Personal Ozone Monitor ............................................................................... 7
3.3. Measurement of the Zero Offset ............................................................................................. 8
3.4. Collecting Data over the USB Port or Serial Port in Real Time............................................... 8
4. GPS 9
5. FRONT PANEL MENU 10
5.1. Menu Tree ............................................................................................................................. 10
5.2. Data Averaging and Data Logging Using the Menu .............................................................. 11
5.3. Navigating the Front Panel Menu .......................................................................................... 11
5.4. Entering the Front Panel Menu ............................................................................................. 11
5.5. Acquiring Data without Logging ............................................................................................. 11
5.6. To Begin Logging Data .......................................................................................................... 12
5.7. To Stop Logging Data............................................................................................................ 13
5.8. To Average Data ................................................................................................................... 14
5.9. Capturing the Transmitted Logged Data Using the USB or Serial Port ................................ 14
5.10. To Set the Calibration Parameters ........................................................................................ 15
5.11. To Set the Time and Date ..................................................................................................... 16
5.12. Viewing the Power Supply Voltage via the Front Panel ........................................................ 16
5.13. Viewing GPS Coordinates via the Front Panel ..................................................................... 16
6. LAMP TEST 17
7. QUIET MODE 18
8. SERIAL AND USB MENU 18
9. USB INSTALLATION 20
9.1. Items Required ...................................................................................................................... 20
9.2. Driver Installation ................................................................................................................... 20
10. USING THE USB CONNECTION 23
10.1. Determine the Connection Port ............................................................................................. 23
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10.2. Using the Connection ............................................................................................................ 24
11. CALIBRATION 25
11.1. Overview ................................................................................................................................ 25
11.2. Equipment Required .............................................................................................................. 26
11.3. Instrument Preparation .......................................................................................................... 26
11.4. Calibration Setup Preparation ............................................................................................... 26
11.4.1. Setup Check ............................................................................................................. 27
11.4.2. Ozone Loss Test ...................................................................................................... 27
11.4.3. Linearity Check......................................................................................................... 27
11.4.4. Intercomparison Test ............................................................................................... 28
12. CALIBRATION PROCEDURE 28
12.1. Instrument Preparation .......................................................................................................... 28
12.2. Measurement of Zero Air ....................................................................................................... 28
12.3. Measurement of Ozone Standards ....................................................................................... 29
12.4. Calibration Curve ................................................................................................................... 29
12.5. Periodic Zero and Span Checks ............................................................................................ 29
13. MAINTENANCE/TROUBLESHOOTING 31
14. LABELED INSTRUMENT PHOTOS 34
15. PARTS LIST 37
16. SERVICE LOG 38
Appendix A: Using the 2B Technologies Display and Graphing Software 40
Personal Ozone Monitor Manual Rev. E-2
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IDENTIFICATION RECORDS
Record the following information for future reference:
Serial number: ______________________________________
Warranty start date: _______________________________________
(date of receipt)
Personal Ozone Monitor Manual Rev. E-2
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PRINTING HISTORY
This manual covers the Personal Ozone Monitor (POM) used for measurement of
ozone concentrations in air. New editions of this manual are complete revisions that
reflect updates to the instrument itself, as well as clarifications, additions, and other
modifications of the text.
Revision A ................................................................................................... March 2012
Revision B ................................................................................................. January 2014
Revision C ............................................................................................... February 2014
Revision D ...................................................................................................... April 2015
Revision E .................................................................................................. August 2016
Rev E-2....................................................................................................... August 2017
(Correction to Equation 2 on page 2; added information in Sections 5.6, 5.8, and 5.10; minor
formatting changes.)
TRADEMARKS & PATENTS
2B Technologies, 2B Tech, 2B, Personal Ozone Monitor and POM are
trademarks of 2B Technologies, Inc.
CONFIDENTIALITY
The information contained in this manual may be confidential and proprietary, and is the
property of 2B Technologies, Inc. Information disclosed herein shall not be used to
manufacture, construct, or otherwise reproduce the goods disclosed herein. The
information disclosed herein shall not be disclosed to others or made public in any
manner without the expressed written consent of 2B Technologies, Inc.
© Copyright 2B Technologies, Inc.
All rights reserved.
Personal Ozone Monitor Manual Rev. E-2
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WARRANTY STATEMENT
2B Technologies, Inc. warrants its products against defects in materials and
workmanship. 2B Technologies will, at its option, repair or replace products that prove
to be defective. The warranty set forth is exclusive and no other warranty, whether
written or oral, is expressed or implied. 2B Technologies specifically disclaims the
implied warranties of merchantability and fitness for a particular purpose.
Warranty Period
The warranty period is one (1) year from date of receipt by the purchaser, but in no
event more than thirteen (13) months from original invoice date from 2B Technologies,
Inc.
Warranty Service
Warranty Service is provided to customers via web ticket, email and phone support,
Monday - Friday, from 9:00 a.m. to 5:00 p.m., Mountain Time USA. The preferred
method of contacting us is through our web ticketing software at:
www.twobtech.com/techsupport
This way all technical staff at 2B Tech will be alerted of your problem and be able to
respond. When you receive an email reply, please click on the Ticket link provided to
continue to communicate with us directly over the internet. The web ticket approach
to customer service allows us to better track your problem and be certain that you get
a timely response. We at 2B Tech pride ourselves on the excellent customer service
we provide.
You may also contact us by email at techsupport@twobtech.com or by phone at
+1(303)273-0559. In either case, a web ticket will be created, and future
communications with you will be through that ticket.
Initial support involves trouble-shooting and determination of parts to be shipped from
2B Technologies to the customer in order to return the product to operation within
stated specifications. If such support is not efficient and effective, the product may be
returned to 2B Technologies for repair or replacement. Prior to returning the product,
a Repair Authorization Number (RA) must be obtained from the 2B Technologies
Service Department. We will provide you with a simple Repair Authorization Form to
fill out to return with the instrument.
Personal Ozone Monitor Manual Rev. E-2
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Shipping
2B Technologies will pay freight charges for replacement or repaired products shipped
to the customer site. Customers shall pay freight charges for all products returning to
2B Technologies.
Conditions
The foregoing warranty shall not apply to defects resulting from improper or
inadequate maintenance, adjustment, calibration or operation by customer.
Maintenance, adjustment, calibration or operation must be performed in accordance
with instructions stated in this manual. Usage of maintenance materials purchased
from suppliers other than 2B Technologies will void this warranty.
Limitation of Remedies and Liability
The remedies provided herein are the Customer's sole and exclusive remedies. In no
event shall 2B Technologies be liable for direct, indirect, special, incidental or
consequential damages (including loss of profits) whether based on contract, tort or
any other legal theory. The Personal Ozone Monitor manual is believed to be
accurate at the time of publication and no responsibility is taken for any errors that
may be present. In no event shall 2B Technologies be liable for incidental or
consequential damages in connection with or arising from the use of the Personal
Ozone Monitor manual and its accompanying related materials. Warranty is valid only
for the country designated on the 2B Technologies quote or invoice.
Personal Ozone Monitor Manual Rev. E-2
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WARNINGS
ENGLISH
WARNING:
Any operation requiring access to the inside of the equipment, could result
in injury. To avoid potentially dangerous shock, disconnect from power
supply before opening the equipment.
WARNING:
This symbol, on the instrument indicates that the user should refer to
the manual for operating instructions.
WARNING:
If this instrument is used in a manner not specified by 2B Technologies,
Inc. USA, the protection provided by the instrument may be impaired.
ESPAÑOL
ATENCION:
Cualquier operación que requiera acceso al interior del equipo, puede
causar una lesión. Para evitar peligros potenciales, desconectarlo de la
alimentación a red antes de abrir el equipo.
ATENCION:
Este símbolo, en el instrumento indica que el usuario debería
referirse al manual para instrucciones de funcionamiento.
ATENCION:
Si este instrumento se usa de una forma no especificada por 2B
Technologies, Inc., USA, puede desactivarse la protección suministrada
por el instrumento.
FRANÇAIS
ATTENTION:
Chaque opération à l’intérieur de l’appareil, peut causer du préjudice. Afin
d’éviter un shock qui pourrait être dangereux, disconnectez l’appareil du
réseau avant de l’ouvrir.
ATTENTION:
Le symbol, indique que l’utilisateur doit consulter le manuel
d’instructions.
ATTENTION:
Si l’instrument n’est pas utilisé suivant les instructions de 2B Technologies,
Inc., USA, les dispositions de sécurité de l’appareil ne sont plus valables.
DEUTSCH
WARNHINWEIS:
Vor dem Öffnen des Gerätes Netzstecker ziehen!
WARNHINWEIS:
Dieses, auf dem Gerät weist darauf hin, dab der Anwender zuerst
das entsprechende Kapitel in der Bedienungsanleitung lesen sollte.
WARNHINWEIS:
Wenn das Gerät nicht wie durch die Firma 2B Technologies, Inc., USA,
vorgeschrieben und im Handbuch beschrieben betrieben wird, können
die im Gerät eingebauten Schutzvorrichtungen beeinträchtigt werden.
ITALIANO
ATTENZIONE:
Qualsiasi intervento debba essere effettuato sullo strumento può essere
potenzialmente pericoloso a causa della corrente elettrica.
Il cavo di alimentazione deve essere staccato dallo strumento prima della
sua apertura.
ATTENZIONE:
Il simbolo, sullo strumento avverte l’utilizzatore di consultare il
Manuale di Istruzioni alla sezione specifica.
ATTENZIONE:
Se questo strumento viene utilizzato in maniera non conforme alle
specifiche di 2B Technologies, Inc. USA, le protezioni di cui esso è dotato
potrebbero essere alterate.
CHINESE
警告：
任何需要接触设备内部的操作均可能造成人身伤害。为避免可能
的触电危险，请在打开设备前切断电源。
警告：
这个符号 在仪器上表示用户应参考说明书上的操作指南。
警告 :
如果仪器没有按照美国2B科技公司指定方式操作，仪器的保护性
能会减弱。
DUTCH
OPGELET:
Iedere handeling binnenin het toestel kan beschadiging veroorzaken.
Om iedere mogelijk gevaarlijke shock te vermijden moet de aansluiting
met het net verbroken worden, vóór het openen van het toestel.
OPGELET:
Het symbool, geeft aan dat de gebruiker de instructies in de
handleiding moet raadplegen.
OPGELET:
Indien het toestel niet gebruikt wordt volgens de richtlijnen van 2B
Technologies, Inc., USA gelden de veiligheidsvoorzieningen niet meer.
JAPANESE
警告：
機器の内部で操作する時、怪我できます。危険な衝撃を回避
するために、機器を開ける前に、電源を切断してください。
警告：
機器でこの記号 を見れば、マニュアルを読んでください。
警告：
この機器は2B テクノロジー会社、US A
の指定でしなければ、機器の保護が損なえます。
Personal Ozone Monitor Manual Rev. E-2
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1. PERSONAL OZONE MONITOR INTRODUCTION
The 2B Technologies Personal Ozone MonitorTM (POMTM) is designed to enable
accurate measurements of ozone in air over a wide dynamic range extending from a
limit of detection of 3 parts-per-billion by volume (ppb) to an upper limit of 10 partsper-million (ppm) based on the well-established technique of absorption of ultraviolet
light at 254 nm. Note that throughout this manual and in the instrument output, “ppb”
(identical to “ppbv”) refers to parts-per-billion by volume (not weight). The Personal
Ozone Monitor is small (4.0″ × 3.0″ × 1.5″; 10.2 × 7.6 × 3.9 cm), lightweight (0.75 lb;
0.34 kg) and has a low power consumption (3.0 watt) relative to conventional
instruments and is therefore well suited for applications such as:
• Long-term monitoring at remote locations where power is highly limited
• Monitoring and control of ozone in industrial settings
• Monitoring of exposure to individuals in the workplace
• Personal exposure monitoring for studies of health effects of air
pollutants
For aircraft flights where high temporal and spatial resolution is desired, the Model
205 Ozone Monitor is recommended.
1.1. Theory of Operation
Absorption of UV light has long been used for measurements of atmospheric ozone
with high precision and accuracy. The ozone molecule has an absorption maximum
at 254 nm, coincident with the principal emission wavelength of a low-pressure
mercury lamp. Fortunately, few molecules found at significant concentrations in the
atmosphere absorb at this wavelength. However, interferences, such as organic
compounds containing aromatic rings, can occur in highly polluted air. For additional
information about UV-absorbing interferences and how to estimate their contributions
see Tech Note #040.
Figure 1.1 is a schematic diagram of the Personal Ozone Monitor. Ozone is
measured based on the attenuation of light passing through a 15-cm absorption cell
fitted with quartz windows. The 15-cm cell length is accomplished by using a “U”
shaped cell with mirrors in the corners to transmit light from the lamp at one end to the
detector at the other. A low-pressure mercury lamp is located on one side of the
absorption cell, and a photodiode is located on the opposite side of the absorption
cell. The photodiode has a built-in interference filter centered on 254 nm, the principal
wavelength of light emitted by the mercury lamp. An air pump draws sample air into
the instrument at a flow rate of approximately 0.75 L/min. A solenoid valve switches
so as to alternately send this air directly into the absorption cell or through an ozone
scrubber and then into the absorption cell.
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Figure 1.1. Schematic Diagram of the Personal Ozone Monitor.
The intensity of light at the photodiode is measured in air that has passed through the
ozone scrubber (Io) and air that has not passed through the scrubber (I). Ozone
concentration, [O3], in units of molecules/cm3 is calculated from the measurements of
Io and I according to the Beer-Lambert Law:
(1)
where l is the path length (15 cm) and is the absorption cross section for ozone at
254 nm (1.15 x 10
-17
cm2 molecule-1 or 308 atm-1 cm-1), which is known with an
accuracy of approximately 1%. The 2B Technologies instrument uses the same
absorption cross section (extinction coefficient) as used in other commercial
instruments.
In order to convert this concentration to a mixing ratio (fraction of total air molecules
that are ozone, we also measure the cell temperature and pressure, which determines
the total concentration of air molecules. From the temperature and pressure, we use
the ideal gas law to calculate the concentration of molecules, M, in the detection cell.
Ozone in units of ppb is then given by:
(2)
where NA is Avogadro’s number (6.02214129 x 1023 molec/mol), R is the gas constant
(82.05746 cm3 atm K
−1
mol
−1
), T is the absolute temperature in K, and P is the cell
pressure in atmospheres.
The instrument displays and records the cell temperature and pressure in addition to
the ozone mixing ratio. The cell pressure is displayed and logged in units of mbar or
torr and the cell temperature in units of either °C or K.
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Shown on Fig. 1 is the DewLine, which serves to make the humidity entering the
detection cell identical during I and Io measurements. Please see our website for a
technical discussion of the DewLine™ and its importance to ozone measurements:
www.twobtech.com/dewline.htm. Briefly, water vapor adsorbed to the inner wall of the
detection cell changes the reflectivity of the cell. If humidity is not the same during I
and Io measurements, an offset in the ozone measurement will occur and can be up to
several tens of ppb for sudden changes in ambient humidity. The offset will change
with time as the internal ozone scrubber equilibrates with water vapor. Even for fixedsite ozone monitors, an offset measurement error will occur if the instrument is zeroed
with dry tank air and then used to measure ozone in humid air. The DewLine
solution to this often-ignored problem is unique to 2B Tech instruments.
In principle, the measurement of ozone by UV absorption requires no external
calibration; it is an absolute method. However, non-linearity of the photodiode
response and electronics can result in a small measurement error. Therefore, each
instrument is compared with a NIST-traceable standard ozone photometer in the
laboratory over a wide range of ozone mixing ratios. These results are used to
calibrate the POM with respect to an offset and slope (gain or sensitivity). The
corrections for offset and slope are recorded in the instrument Birth Certificate. These
calibration parameters are entered into the microprocessor prior to shipment. The
user may change the calibration parameters from the front panel if desired. It is
recommended that the instrument be recalibrated at least once every year and
preferably once every six months. The offset may drift due to temperature change or
chemical contamination of the absorption cell. As discussed below, an accurate offset
correction can be measured from time to time using the external ozone scrubber
(Zeroing Cartridge) supplied with the instrument.
An animated video explaining how a UV-absorbance ozone monitor works is posted
on the 2B Tech website at: http://twobtech.com/videos_general.htm
Personal Ozone Monitor Manual Rev. E-2
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1.2. Adaptive Filter
The POM firmware processes sample concentration data through a built-in adaptive
filter. During operation, the firmware may automatically switch between two different
filter lengths based on the conditions at hand. During the measurement of stable
concentrations, the firmware, by default, computes an average of the last 50 raw (2second) measurements, or approximately 1.5 minutes. This provides smooth and
stable readings by averaging out a considerable amount of random noise to improve
the precision. If the filter detects rapid changes in concentration, the filter reduces the
averaging to only 10 samples or about 20 seconds to allow the analyzer to respond
more quickly. Two conditions must be simultaneously met to switch to the short filter.
First, the instantaneous concentration must differ from the average in the long filter by
at least 15 ppb. Second, the instantaneous concentration must differ from the
average in the long filter by at least 5% of the average in the long filter. The lengths of
the long and short filter can be changed as well as the minimum difference and
percent difference. This can be done via the serial or USB connection as outlined in
the Serial Menu section in this manual (Section 8).
As shipped from the factory, the default settings of the adaptive filter are: short filter
length = 10, long filter length = 50, difference = 15, and percent difference = 5%. To
disable the adaptive filter, set the short filter length to 1, the difference to 0, and the
percent to 0.
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2. SPECIFICATIONS
2.1. Overview
2B Tech has taken the next step in miniaturization of UV-based ozone monitors by
developing the Personal Ozone Monitor or “POM.” The POM has dimensions of 4 × 3
× 1.5 inches and weighs only 0.75 lb. (340 g). It has a built in GPS so that ozone
measurements may be logged continuously along with geographic location. By
folding the optical path in the shape of a “U,” it was possible to achieve the same path
length in the POM as in the Models 202, 205, and 106-L and thus have similar
precision and accuracy (~1.5 ppb or better). The POM’s many possible applications
include:
• Personal exposure monitoring for studies of health effects of air pollutants
• Health and safety monitoring at industrial sites using ozone
• Citizen science and educational measurements such as GO3 Treks
• Vertical profiling using balloons, kites, RPVs and light aircraft where space and
weight are highly limited
• Long-term monitoring at remote locations where power is highly limited
• Urban arrays of ground-based detectors
Detailed specifications are given in the table on the next page.
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2.2. Table of Specifications: Personal Ozone Monitor (PAM)
Measurement Principle
UV Absorption at 254 nm
Federal Equivalent Method (FEM)
Yes, EQOA-0815-227
Linear Dynamic Range
0 ppb to 10 ppm
Resolution
0.1 ppb
Precision (1σ; rms noise)
Greater of 1.5 ppb or 2% of reading
(10-s measurement mode, with default adaptive filter settings)
Limit of Detection (2σ)
3.0 ppb
(10-s measurement mode, with default adaptive filter settings)
Accuracy
Greater of 1.5 ppb or 2% of reading
NIST-Traceable Calibration
Yes
Measurement Intervals
Measurement mode: 10 s; Fast mode: 2s
Flow Rate (nominal)
~0.8 Liter/min
Flow Rate Requirement
>0.5 L/min
Baseline Drift
<2 ppb/day; <5 ppb/year
Sensitivity Drift
<1%/day; <3%/year
Measurement Time, Frequency
10 s, 0.1 Hz (Fast mode: 2s, 0.5 Hz)
Response Time, 100% of Step
Change
For 10-s output: 20 s, 2 data points
For 2-s output: 4s, 2 data points
Data Averaging Options
1 min, 5 min, 1 hr
Data Storage
8,192 lines (2-s fast mode ~4.6 hrs; 10-s meas. mode ~1
day; 1-min avg ~6 days; 5-min avg ~1 mo; 1-hr avg ~1 yr)
Ozone Units
ppb
Pressure Units
torr
Temperature Units
K
T and P Corrected
Yes
Operating Temperature/
Pressure/Altitude Ranges
0 to 50°C; 150-1013 mbar; 0-13.5 km
[lower pressure range available as an option]
Power Requirement;
Supplied by battery or 110/220
VAC Power Pack
7-24 V dc, nominally 250 mA at 12 V, 3.0 watt
External Battery
7.4 volt, 1.6 amp hour, Lithium Ion Battery, 5-8 hr
Size
With GPS: 5.5 × 3.0 × 1.5 inches (14.0 × 7.6 × 3.8 cm)
Without GPS: 4.0 × 3.0 × 1.5 inches (10.2 × 7.6 × 3.8 cm)
Weight
1.0 lb (454 g); without battery: 0.8 lb (360 g)
Data Transfer Baud Rate
19200
DewLineTM
Yes
GPS
Yes
Personal Ozone Monitor Manual Rev. E-2
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3. OPERATION
Please read all the following information before attempting to operate the Personal
Ozone Monitor. For assistance, please call 2B Technologies at +1(303)273-0559.
NOTE:
Save the shipping carton and packing materials that came with the
Personal Ozone Monitor. If the Personal Ozone Monitor must be returned
to the factory, pack it in the original carton. Any repairs as a result of
damage incurred during shipping will be charged.
3.1. Shipping Box Contents
Open the shipping box and verify that it contains all of the items on the shipping list. If
anything is missing or obviously damaged, contact 2B Technologies immediately.
3.2. Operation of the Personal Ozone Monitor
To operate the Personal Ozone Monitor, connect it to an external power source and
power the instrument by switching the power switch on. The instrument requires a 724 V DC source which can be supplied by: 1) the 100-240 V AC power adapter, 2) a
cigarette lighter adapter plugged into a 12 V DC source such as found in an
automobile or many light aircraft, or 3) a 7-24 V battery. The source can be in the
range 7-24 V DC without any detrimental effects on the measurement. When using a
battery, be certain to attach the positive (red) and negative (black) wires correctly.
Batteries and battery chargers are available from 2B Technologies. A circuit breaker
and diode are installed on the circuit board in case of an electrical short or incorrect
battery attachment. If activated, the breaker will reset itself after a few minutes. Also,
for safety purposes the provided 7.4-V lithium ion battery has its own protective circuit
in case of a short.
Turn the instrument on with the small switch between the power connection and the
GPS antenna (see Figure 14.2). Once turned on, the instrument will display the
version number of the software installed on the microprocessor. After a few seconds,
the instrument will start displaying readings for ozone. The first dozen readings
(requiring about two minutes) will be spurious, with large positive and negative swings
due to the rapid warmup of the lamp and electronics. Also, ozone readings may be
inaccurate during the 10-20 minutes required for the lamp, photodiode, and internal
temperature of the absorption cell to stabilize.
Inlet tubing may be attached to the white fitting on the front of the instrument (see
Figure 14.1). The inlet tubing should be made of PTFE (Teflon), PFA, FEP, PVDF,
or some other inert material that does not destroy ozone and that does not desorb
Personal Ozone Monitor Manual Rev. E-2
8
plasticizers and other organics that can contaminate the flow path. The length of
tubing should be kept as short as possible (preferably not more than a few feet) to
minimize ozone destruction within the inlet tubing. Tygon, polypropylene (which may
look like Teflon), and metal tubing should not be used. FEP-lined Tygon tubing, which
is used inside the instrument, provides the flexibility of Tygon with the inertness of
FEP. A Teflon or PVDF inlet filter is highly recommended to prevent internal
contamination of the tubing and absorption cell by particulate matter. The filter should
be tested for ozone loss by measuring ambient ozone with and without the filter
attached. Filters and filter holders are available through 2B Technologies.
Although the instrument compensates for temperature drift, if strong temperature
fluctuations are expected, as in vertical profiling applications using balloons, the
instrument should be placed in a thermally insulated box.
3.3. Measurement of the Zero Offset
The electronic zero of the instrument may be measured by attaching an ozone zeroing
scrubber (2B Technologies part no. ZEREXTPOM or other ozone destruction cartridge) to
the air inlet for a period of 5-10 minutes. For an accurate measurement, the instrument
must have been turned on long enough for the internal temperature to stabilize. The
observed offset, which can amount to a few ppb, can be corrected for by changing the
offset calibration parameter (Z) from the front panel, as described in Section 5.10 below.
3.4. Collecting Data over the USB Port or Serial Port in Real Time
To transmit data to a computer over the USB port or the serial port in real time,
connect the Personal Ozone Monitor to the serial port of the computer using the
stereo plug to D9 serial cable provided. Start your data acquisition software,
preferably using the 2B Technologies Display and Graphing Software (available as a
free download from http://twobtech.com/downloads_software.htm; see Appendix A for
a description of working with this software). Other terminal emulation software such
as HyperTerminal (a program provided with earlier versions of Windows) or Tera Term
may be used as well.
The ozone mixing ratio (ppb), internal cell temperature (K), cell pressure (torr), time,
and date are sent as comma-delimited ASCII text to the serial and USB ports (19200
baud as selected in the menu; 8 bits; no parity; 1 stop bit) every 2 seconds, 10
seconds, 1 minute, 5 minutes, or 1 hour, depending on the averaging time selected
from the microprocessor menu. Time is provided in 24-hour (military) format, and the
date is given in European style (day/month/year).
A typical data line would read:
3.2,307.4,608.1,1.2740,12.1,4001.27765,-10513.0308,1591.20,1,23/03/12,16:39:14
where:
Ozone = 3.2 ppb
Cell temperature = 307.4 K
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