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Calibration Handbook VIS-NIR
optek-Manual--1004-5003-02--Calibration-Handbook-VIS-NIR-US-2012-06-28.pdf
PN: 1004-5003-02 (-52)
optek-Danulat GmbH Emscherbruchallee 2 45356 Essen Germany
Telefon: +49-201-63409-0 Fax: +49-201-63409-999 E-Mail:
[email protected] Internet: www.optek.com
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Preface
This handbook is written to assist the user in proper procedures
for trouble-free operation.
It is explicitly pointed out that optek-Danulat GmbH assumes no
respon-sibility for loss or damage caused due to improper use of
this handbook or products described herein.
This manual is protected by copyright. However, the user may
produce copies and translations if required for correct operation
of the products.
On request, this manual is available in other languages as well
as in digital format (Acrobat Reader 7.0 required).
Our products are being continuously improved. Technical data is
subject to change without notice.
Essen, June 2012
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Table of contents
Preface
1. Using the handbook
.................................................................................................1
1.1. Validity of the handbook
.........................................................................................1
1.2. Pictograms and signal words
.................................................................................2
2. Intended
use..............................................................................................................3
3. Safety
.........................................................................................................................4
4. Introduction
...............................................................................................................5
4.1. Traceability
.............................................................................................................5
4.1.1.
Overview.................................................................................................................5
4.1.2. Traceability of optek calibration filters
....................................................................6
5. Calibration of optek VIS and NIR
sensors..............................................................7
5.1. Photometric accuracy and linearity
........................................................................7
5.1.1.
Overview.................................................................................................................7
5.1.2. Calibration Device
..................................................................................................7
5.1.3. Calibration Certificate
.............................................................................................9
5.2. Spectral properties
.................................................................................................9
5.2.1.
Overview.................................................................................................................9
5.2.2. Calibration
Devices...............................................................................................10
6. Handling and
Storage.............................................................................................11
6.1. Handling and Storage of optek Calibration
Filters................................................11 6.2.
Handling of Calibration
Cuvettes..........................................................................12
6.3. Cleaning of optek Calibration Filters and Cuvettes
..............................................12
7. Calibration Procedures
..........................................................................................13
7.1. General Procedure
...............................................................................................13
7.2. Calibration with Calibration
Filter..........................................................................14
7.2.1. Photometric Accuracy and
Linearity.....................................................................14
7.2.1.1. Example Filter Calibration Photometric Accuracy and
Linearity .......................14 7.3. Calibration with
Calibration Cuvette
.....................................................................16
7.3.1. Spectral Properties
...............................................................................................16
7.3.2. Example Calibration with FH03 Calibration Cuvette
............................................16
8. Linearization Curves
..............................................................................................18
8.1. General Procedure
...............................................................................................18
9.
Glossary...................................................................................................................19
10. Spare parts
..............................................................................................................21
11.
Appendix..................................................................................................................22
11.1. Declaration of
decontamination............................................................................22
11.2.
Disposal................................................................................................................22
11.3. Sample certificate for VIS-L090 Calibration Filter
................................................23 11.4. Contacts
...............................................................................................................26
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1. Using the handbook 1.1. Validity of the handbook
This handbook is only valid for optek calibration filters
described in chapter 2, page 3 in combination with the inline
sensors for VIS and NIR absorption indicated in chapter 4, page 5.
Follow this handbook for every operation. Furthermore always
observe the handbook of each measuring system to be checked. If the
calibration filters are not used according to this handbook, the
function of the cali-bration filters and the measuring system to be
checked may be affected. To maintain reliability of the product,
enhance its life cycle and avoid down times, follow the
instructions given in this manual. Furthermore, please follow local
accident prevention and environmental protection instructions, as
well as recognized technical regulations for safe and professional
operation.
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1.2. Pictograms and signal words Important information in this
handbook is marked with the following pictograms:
Danger! This pictogram indicates immediate danger to life and
health of persons. The
text next to the symbol gives information on how to avoid bodily
injuries.
Danger! Electrical voltage.
This pictogram indicates danger due to electrical voltage.
Caution! This pictogram indicates information on how to avoid
material damage.
Note! This pictogram indicates instructional or general
advice.
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2. Intended use optek calibration filters and cuvettes shall
only be used as a means for calibration of inline sensors for VIS
and NIR absorption indicated in chapter 4, page 5. The term
calibration is employed here in accordance with the definition of
the International vocabulary of metrology Basic and general
concepts and associated terms1 Constructional changes as well as
changes to and interference with the described procedures for using
the calibration filter are prohibited. Calibration with optek
calibration means shall only be carried out by trained and
qualified personnel. The warranty for calibration filters as well
as for corresponding certificates including product traceability
ex-pires in case of improper use, removal of the calibration filter
from the fil-ter holder, or modification of the labelling. optek
does not assume liability for loss or damage resulting from use of
calibration filters. Following this handbook is part of the
intended use.
1 International vocabulary of metrology- Basic and general
concepts and associated terms ed.: DIN, German Institute for
Standardization 2nd edition 1994
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3. Safety
Only use the calibration filter when free from defects and in
accordance with the instructions provided in this handbook.
Read this handbook prior to initial commissioning. This
especially applies to personnel who only occasionally carry out
calibrations with calibration filters.
Observe all safety and information labels on the product and
keep them in readable condition.
Inspect the product for signs of physical damage. Report any
damage immediately and do not commission the product until
corrective actions have been taken. Protect calibration filters and
cuvettes from external influences which could affect proper
function, such as dust, humidity or fingerprints.
Do not use calibration filters or cuvettes with visible damage
to the filter glass or filter holder. Have such calibration means
immediately checked by the manufacturer.
Spare parts must comply with technical requirements defined by
optek. This is always guaranteed when using original spare
parts.
This safety information is supplemented by the current national
and local regulations on accident prevention and the recognized
technical instruc-tions for safe and professional operation.
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4. Introduction
This handbook is a description of opteks VIS and NIR calibration
filters and calibration cuvettes used to test the functionality of
optek AF16-N, AF16-F, AS16-N, AS16-F and AF26 sensors. This test
applies to the entire measuring chain consisting of converter,
sensor and cable set. optek offers VIS and NIR calibration means
for the following tests: a) Calibration of photometric accuracy and
linearity (chapter 5.1 page 7
and chapter 7.2.1 page 14) b) Calibration of spectral properties
(chapter 5.2 page 9 and chapter
7.3.1 page 16) The available calibration filters are test
devices traceable to NIST and used to calibrate VIS and NIR sensors
at user-defined and application-dependent frequencies.
Determination of calibration frequencies is the users
responsibility.
4.1. Traceability
4.1.1. Overview
The International vocabulary of metrology Basic and general
concepts and associated terms defines traceability as the property
of the result of a measurement or the value of a standard whereby
it can be related to stated references, usually national or
international standards, through an unbroken chain of comparisons
all having stated uncertainties. These stated references can be
standards developed and maintained by national or international
metrological institutes, such as the Deutsche
Physikalisch-Technische Bundesanstalt (the national metrology
institute in Germany) or the National Institute of Standards and
Technology (NIST) in the USA, or transfer standards that are linked
to other working standards. The unbroken chain of comparisons is
referred to as a complete, ex-plicitly described and documented
series of comparisons that succes-sively link the value and
uncertainty of a result of measurement with the values and
uncertainties of each of the intermediate reference standards and
the highest reference standard to which traceability for the result
of measurement is claimed. Traceability is thus a property of a
measurement and not a property of a device, calibration
certificate, or laboratory. A spectrophotometer, for example,
cannot be NIST-traceable. It can only be a calibrated
spectrophotometer, whose measurements are traceable to NIST.
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4.1.2. Traceability of optek calibration filters
Spectrophotometers and photometers are special with respect to
trace-ability since they deliver dimensionless measuring results
which can thus not be traced back to SI basic units. The unbroken
chain of comparisons in this case ends with measurements of a
reference spectrophotometer in the NIST Advanced Chemical Sciences
Laboratory(ACSL). Certification of optek calibration filters is
carried out in the optek calibra-tion laboratory according to the
recommendations of ISO 17025. In the center of the calibration
laboratory is a spectro-photometer (Varian Cary 5000) which is
subject to rigid inspection of measuring and test equip-ment in the
course of which calibrations are carried out in permanently defined
intervals using NIST Standard Reference Material (SRM). Just like
the spectro-photometer are these SRMs also subject to a detailed
determined inspection of measuring and test equipment and are
recali-brated at regular intervals in a certified calibration
laboratory. Details regarding used reference materials and required
indications with respect to the description of traceability are
given in the respective optek calibration certificate. Since the
application range of NIST SRM is restricted to the UV-VIS
wavelength range, measurements at wavelengths above 800nm cant be
NIST traceable even if they were carried out with a
spectrophotometer whose measurements are NIST traceable calibrated.
Nevertheless, optek is able to provide reliable and precisely
calibrated calibration filters for optek NIR photometers. For that
purpose optek uses reference calibration filters as transfer
standards between an optek reference NIR photometer and the
spectrophotometer of the optek calibration laboratory. Prior to the
calibration of a reference calibration filter with the optek
reference photometer the photometer was calibrated by using the
double aperture method. Details regarding used reference materials
and required indications are given in the respective optek
calibration certificate.
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5. Calibration of optek VIS and NIR sensors
5.1. Photometric accuracy and linearity
5.1.1. Overview
The goal of this test is to check the measuring chain,
consisting of sen-sor, cable and converter, with respect to
photometric accuracy. When in-troduced into the light beam,
Calibration filters cause a defined light at-tenuation at
individual wavelengths and wavelength ranges. Using cali-bration
filters with different absorption levels tests linearity of the
entire system. Insufficient photometric accuracy or linearity may
be caused by the fol-lowing effects:
Non-linearity of used SI photodiodes, for instance, due to
component de-fects or humidity deposits on the diode bonding
Hardware failure of the converter, e.g. defective input cards
Faulty wiring of sensor and converter Damaged cable plugs or
termination on sensor and / or converter Wrong product definition
due to selecting the wrong measuring function Unintentional or
accidental activation of calibration functions, such as Sensor
Adaptation, Offset & Slope, Linearization Tables, or mA inputs
affecting raw measuring values
5.1.2. Calibration Device
optek offers calibration filters VIS-L045 through VIS-L180 and
NIR-L045 through NIR-L180 with nominal absorption values of 0.45
CU, 0.90 CU and 1.80 CU. These filters are almost
wavelength-independent and therefore suitable for the specified
wavelengths and wavelength ranges. To minimize the influence of
reflections on filter surfaces, these filters are mounted in the
holder in an angled position (see fig. 1), which brings the
measurement values in a process photometer closer to those of a
certified spectrophotometer. Since instrument specifications, such
as sensor types and designs, sensor bodies, optical path length
(OPL) and others, may vary and, hence, have a slight impact on the
VIS-L and NIR-L filter readings, it is necessary to discriminate
between initial and subsequent calibration. This allows using the
calibration filter for calibrating any type of optek VIS or NIR
photometer specified in chapter 4, page 5. Fig.1: FH03B filter
holder with filter installed in an angled position
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a. Initial calibration During the initial calibration, the
initial value of a measuring system is re-corded. The tolerance of
the desired value is stated in the table 1 on page 8. If the
measuring system passes initial calibration, it is very unlikely
that the tested system exhibits insufficient photometric accuracy
or limited linearity, caused by effects described in chapter 5.1.1,
page 7. Initial values as recorded only apply to the photometer
tested. They cannot be applied to any other photometer but are
always required to be established for each photometer separately.
After constructional changes of the photometer, the initial value
must be recorded again. Constructional changes are:
Change of interference filters or detector module
Change of OPL
Retrofit or change of sensor body b. Subsequent Calibration For
subsequent calibrations, the initial value as recorded and
docu-mented during initial calibration serves as the desired
(nominal) value of the individual photometer. For a subsequent
calibration to pass, the measured value must be within a certain
tolerance of the initial value. The exact tolerances for different
filters and systems are listed in table 1 on page 8.
Table 1: Tolerances for initial and subsequent calibration of
optek photometers with optical path lengths up to 160mm.
Initial Subsequent AF16-N AS16-N AF16-F AS16-F AF26
0.02 CU 0.03 CU 0.06 CU VIS-L045 n.a. n.a. 0.01 CU 0.015 CU 0.03
CU 0.03 CU 0.06 CU 0.06 CU VIS-L090 n.a. n.a. 0.01 CU 0.03 CU 0.03
CU 0.03 CU 0.065 CU VIS-L180 n.a. n.a. 0.01 CU
n.a 0.03 CU
0.015 CU 0.02 CU NIR-L045 0.01 CU 0.015 CU
n.a. n.a. n.a.
0.02 CU 0.03 CU NIR-L090 0.01 CU 0.015 CU
n.a. n.a. n.a.
0.03 CU 0.04 CU NIR-L180 0.01 CU 0.015 CU
n.a. n.a. n.a.
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5.1.3. Calibration Certificate VIS-L and NIR-L Filters available
from optek are delivered with a calibra-tion certificate. A sample
certificate is included in the appendix (chapter 11.3, page 23) of
this handbook. Each of these calibration certificates contains,
among other information, the following important information:
Certificate number Calibration filter type with serial number
Via serial number, which is also engraved on the filter holder
of the calibration filter, calibration certificate and calibration
filter are cross-referenced to each other
Nominal absorption value of the filter Certified absorption
value including expanded uncertainty for respec-
tive VIS and NIR wavelengths Measuring conditions, at which
absorption values were recorded Spectrophotometer used for
certified measurements including refer-
ence standards used for calibration of the device Application of
the calibration filter to optek VIS and NIR sensors
An example is given in chapter 7.2.1.1, page 14.
5.2. Spectral properties
5.2.1. Overview
Evaluations of spectral properties are not straightforward and
require a more detailed explanation. Spectrophotometers require
calibration of spectral resolution and accuracy. Resolution,
however, is not defined for instruments that are not adjustable in
frequency (or wavelength). By the same token, spectral accuracy of
photometric systems cannot be deter-mined by the location of
transmission maxima. In photometers, the effective measuring
wavelength is not only determined by instrument properties of the
photometer but also by spectral characteristics of the compound to
be analyzed. Instrument properties of a photometer are primarily
defined by the installed optical filter, which is characterized by
parameters, such as mean wavelength, and Full Width at Half Maximum
(FWHM), and may vary within certain (tight) tolerances. If and to
what extend this may effect the measurement, depends on the
application itself. The best, and probably the only calibration of
a process photometer with respect to concentration as the measuring
quantity is the use of the product to be analyzed or monitored by
the photometer. To this end, optek has introduced the FH03
calibration cuvette. Such calibrations using actual product may be
carried out at defined frequencies and always prior to
commissioning a VIS or NIR photometer. The advantage of doing so is
the direct applicability of test results to the process
meas-urement.
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5.2.2. Calibration Devices As already mentioned, the absorption
spectrum of the compound to be measured also has an impact on the
spectral response properties of the photometer, which is why
testing of these properties must be performed with regard to the
intended application. The most efficient way of testing spectral
properties is, using the FH03 Calibration Cuvette (see. Fig. 2)
filled with the compound to be measured. The exact procedure is
described in chapter 7.3, page 16. Fig.2: Calibration Cuvette
FH03
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6. Handling and Storage
6.1. Handling and Storage of optek Calibration Filters Since
optek calibration filters serve as important calibration tools,
they require very careful handling so that their functionality is
not affected by external influences. Calibration filters should be
stored in the filter storage boxes provided at ambient temperatures
from 15C to 30C (59F to 86F) and a relative humidity not exceeding
70 %. Especially dust, streaks, finger marks or scratches can
damage the calibration filter and require recertification. Observe
the following basic conditions: Do not remove the calibration
filter from the mounting. Do not change the filters orientation
inside the filter holder. Do not scratch the surface. For
protection, store calibration filters under exclusion of UV light
in
a dust-and oil-free place. The air should be free of corrosive
vapor. Storage temperature: 15C to 30C (59F to 86F) Air humidity: 0
% to 70 %
Note! Store calibration filters in dry cabinets or other
appropriate cabinets so that the filters are protected against
variations in temperature and humidity.
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6.2. Handling of Calibration Cuvettes Please observe the
following handling instructions for opteks FH03 cali-bration
cuvette: Prior to use, calibration cuvettes should be checked for
cracks,
chips, and scratches and replaced if necessary. Always handle
cuvettes with special care to keep inner and outer
surfaces clean and to avoid scratches. Before filling cuvettes
with any solution, rinse them with distilled
water. After that, cuvettes should be partly filled with
solution, shaken and turned upside down so that the solution wets
the inner surface of the cuvettes. The solution should be discarded
and the cuvette rinsed with water again.
Humidity and finger marks should be removed with lint-free paper
or lens cleaning paper.
Do not clean cuvettes in an autoclave or in ultrasonic baths
since cuvettes could be damaged.
Cuvettes should be stored in their corresponding boxes.
6.3. Cleaning of optek Calibration Filters and Cuvettes Prior to
use, visually inspect calibration filters and cuvettes for dust or
other soiling such as finger marks or condensation and clean them
if necessary. Carefully remove any surface soiling capable of
absorbing light or particles that might scatter incident radiation:
Carefully remove surface particles using a soft lens brush that
does
not scratch the optical surface. Remove absorbing surface
soilings with a solvent that is non-
alkaline and free of surfactants (e.g. Isopropanol). Note:
Calibration filters should only be cleaned when required. As a
basic rule, it is recommended to avoid any soiling, especially
finger marks, through proper handling of calibration filters and
cuvettes.
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7. Calibration Procedures
The following chapter deals with the calibration procedures
using test devices introduced in chapter 5, page 7. The described
procedures only apply to optek VIS and NIR Sensors AF16-N, AF16-F,
AS16-N, AS16-F and AF26. All calibration procedures are described
in general. For further information, please refer to the
instruction manuals of the particular converters and sensors.
7.1. General Procedure
1. Preparation The system to be calibrated must be wired and
fully operational. Allow analyzer at least 30 minutes to warm up.
Make sure detector assemblies are tightly screwed onto measuring
cell, otherwise measurement results will be compromised.
2. Sensor Identification Record serial numbers of sensor and
converter as well as activated measurement input channels of the
converter.
3. Filter Identification Record serial number, filter type, date
of calibration and nominal values.
4. Sensor Body and Zero Medium All procedures require a clean
and empty sensor body or a sensor body completely filled with
stable zero medium. It is not necessary to remove the sensor body
from the pipeline. Also ensure that there is no condensation or
soiling on the windows.
5. Zero Point Adjustment / Record Initial Value If possible,
zero the instrument. Otherwise, record the current measuring
values.
6. Record / Disable Additional Measurement Functions In case
your measuring values are using calibration functions, such as
Sensor Adaptation, Linearization, Damping or mA inputs, record all
relevant values. If several calibration functions are being used,
it is recommended creating your own Calibration Product in the
C4000 converter. C4000 converters with software version C2 from
December 11th, 2007, or later versions may use the Detector Monitor
displaying raw measuring values. For further information on the
product definition and the detector monitor, please refer to the
C4000 instruction manual.
7. Remove Sealing Cover and Insert Filter Loosen the 2 screws of
the sealing cover of the detector adapter
and remove sealing cover and screws. Take filter holder out of
storage box and visually inspect reference
filter for dust or soiling. Clean it if necessary. Insert filter
holder in the detector adapter- the two pilot pins must
be inserted in the alignment holes.
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Fig.3: Insert Calibration Filter
Note: The screws on the sealing cover are not secured against
falling out. Make sure not to loose any screw.
8. Record Measuring Result
Record displayed measuring result. 9. Evaluation of Measuring
Result
Take calibration functions into account that are activated, then
com-pare resulting value with certified nominal value on
certification.
7.2. Calibration with Calibration Filter
7.2.1. Photometric Accuracy and Linearity This test determines
the accuracy and linearity of the photometer with respect to the
certified nominal values. Nominal values for the photometric
accuracy and linearity tests are the values given in the
calibration certificate on first page. Tolerances are given in the
calibration certificate on third page, chapter Instructions for
use.
7.2.1.1. Example Filter Calibration Photometric Accuracy and
Linearity
The following example documents a photometric accuracy test
using an NIR-L090 calibration filter and sensor AF16-N. The
converter settings chosen for this example include sensor
adaptation and processing a mA-input. These settings must be taken
into account when determining the measuring result, as shown in
this example.
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Table 2: Example Initial Filter Calibration. Photometric
Accuracy and Linearity
No. Description: Data:
01 Filter Type: NIR-L090
02 Filter ID: FH03B-11111-22
03 Calibration Date: 31.03.2010
04 Certified Value: 0.889CU
05 Admissible Range: 0.869 0.909CU
06 Serial Number Sensor: 12345
07 Serial Number Converter: 12346
08 Measurement Input: A
09 Sensor Adaptation ABS-CU (A): 0.9
10 Multiplication mA Input 1: yes
11 Value mA-Input: 50%
12 Measuring Result Zero Medium: 0.002
13 Measuring Result Calibration Filter: 0.401
14 Measuring Result minus Offset Zero Point (No. 12)
0.401CU-0.002=0.399
15 Compensate for Sensor Adaptation (No. 09) * (1/0.9)=
0.443
16 Compensate for mA Input (No. 10,11) * (1/0.5)=0.886
22 Calibration Value: 0.886 CU
23 Evaluation: passed For a subsequent calibration, this means:
Admissible Range: 0.877 0.895
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7.3. Calibration with Calibration Cuvette
7.3.1. Spectral Properties
In chapter 5.2.1, page 9, calibration with the FH03 calibration
cuvette filled with product or a specified calibration liquid has
already been described as the best calibration method for
photometers. This procedure tests the photometer in one single test
step. When using the FH03 calibration cuvette, some additional
aspects must be observed apart from the basic steps described in
chapter 7.1, page 13. It is most important to note that the
correlation between absorption and concentra-tion does not
primarily depend on the concentration but on the reported
absorp-tion. For this reason, differences in OPL between sensor
body and cuvette must be corrected by a conversion factor m.
Normally this procedure results in smallest deviations between
cuvette and sensor body measurements. Table 3: Conversion Factor m
as a Function of Sensor Body OPL
OPL [mm] 1.0 2.5 5.0 10 20 40 Conversion Factor m 0.4 1 2 4 8
16
For testing a photometer with the FH03 calibration cuvette, the
product to be analyzed or any appropriate calibration liquid can be
used. When choosing a calibration liquid, it is important its
spectrum matches the product spectrum as much as possible. The
concentration of the calibration liquid in the cuvette should
roughly represent the absorption of the working point. This method
also consists of initial and subsequent applications. A subsequent
calibration with an FH03 calibration cuvette requires the test
liquid be identical with that used for initial calibration. Since
preparation of a test liquid always involves some uncertainties,
and the absolute concentration of a product sam-ple can also vary
within certain limits, possible differences in concentration
between initial and subsequent calibration must be taken into
account. For this reason, it is recommended to establish a
correlation between reference meas-urement and photometric
measurement during initial calibration. It is the users
responsibility to choose the appropriate reference measurement,
such as a spectrophotometric measurement or the absolute mass of a
test liquid. In many cases, correlation was already established
during the qualification process of the measuring system. In these
cases, the characteristic curve for determining the actual
concentration and the resulting nominal value should be used for
calibration.
7.3.2. Example Calibration with FH03 Calibration Cuvette
A concentration of 100 mg/l of a substance is to be measured in
a sensor body with 10 mm OPL (m=4). The weight concentration (mass)
of this substance serves as a reference. The accuracy of
concentration is estimated to be ap-proximately 2 %. Therefore,
calibration points are chosen to be apart by 5 % increments.
Table 4: Example Calibration with FH03 Calibration Cuvette
WorkingPoint
Calibration Point
ConcentrationCuvette
Measured CU Value
95 % 380 mg/l 0.740 CU 100 % 400 mg/l 0.800 CU
100 %
105 % 420 mg/l 0.860 CU
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Thus, slope is 0.003 CU/mg/l (in the cuvette), and concentration
uncertainty is 0.5 % (here 2 mg/l), corresponding to 0.006 CU
tolerance range for the photometric measurement.
Fig. 4 shows the correlation between reference measurement
(concentration in [mg/l]) and photometric measurement, which will
be used in subsequent cali-brations for determining the photometric
nominal value.
Fig. 4: Example of a Calibration Curve For a subsequent
calibration, this means:
Table 5: Subsequent Calibration
Target Concentration
Actual Concentration
Absorption Out
Absorption In
Value O.K.?
400 mg/l 399 mg/l 0.796 0.006 CU 0.795 CU yes
Uncertainties including those of the sensor cannot be discussed
here due to the large number of possible applications. However, it
is important to note that the test will have passed if the
photometric value is found to be within the un-certainties.
0.796
0.7
0.75
0.8
0.85
0.9
370 380 390 400 410 420 430c [mg/l]
CU
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8. Linearization Curves
Linearization Curves can be defined at select converters or in
downstream sig-nal processing. They can serve to convert measuring
result to other unit scales (mostly concentrations). Especially for
non-linear correlations between concentration and absorption, use
of linearization curves is recommended. When using the FH03
calibration cuvette (apart from some basic steps described in
chapter 7.1, page 13), some additional aspects must be observed as
well. It is important to note that the correlation between
absorption and concentration depends more on reported absorption
than on concentration. For example, double concentration does not
necessarily mean double absorbance. For this reason, differences in
OPL between sensor body and cuvette must be corrected by a
conversion factor m.
8.1. General Procedure
1. Define maximum product concentration (cPmax) to be measured
in the process.
2. Define the optical path length (OPL) of your sensor body.
Depending on the OPL of the sensor body, conversion factors m for a
calibration cuvette with 2.5 mm OPL are as follows.
Table. 6: Conversion Factor m as a Function of Sensor Body
OPL
OPL [mm] 1.0 2.5 5.0 10 20 40 Conversion Factor m 0.4 1 2 4 8
16
3. Prior to establishing a linearization curve, make sure
linearization tables that
may previously have been activated are disabled. In case mA
input channels or sensor adaptations are active, determine to what
extent they apply to the expected result and whether they affect
measurement the same way as in the cuvette (such as temperature
compensation).
4. It is recommended to establish a linearization curve using at
least three cali-bration points, including relative concentrations
of 0 % (zero medium), 50 % and 100 %. In this case concentrations
required for cuvette measurement are 0.5*m* cPmax and m* cPmax.
Depending on measuring range and curve shape, the user may decide
to increase number of calibration points in the lineariza-tion
table, if deemed necessary.
Table 7: Linearization
Product Concentration cP in the process
Product concentration cC in the cuvette
CU value measured with
cuvette
0 0
* cPmax *m* cPmax
cPmax m*cPmax
Output values in the Linearization table
Input values in the
Linearization table
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9. Glossary Table 7: Glossary
Term Explanation
Adjustment Operation of bringing a measurement system into a
state of per-formance suitable for its use, such as adjusting an
output value of a measuring system until its reading agrees with
that of a reference standard.
AU Absorption Unit The dimensionless absorption value of log
(1/T). T = % Transmission
Calibration Operation of establishing, under specified
conditions, the relation-ship between values of quantities
indicated by a measuring system and corresponding nominal values
(calibration standards).
Conversion Factor m Factor that accounts for the difference in
OPL between calibration cuvette (2,5 mm OPL) and inline sensor body
in the process. Used to calculate the concentrations of calibration
standards in the cu-vette, whose absorption values are equivalent
to those found in the process sensor body at a different OPL.
CU Concentration Unit The dimensionless absorption value of log
(1/T) measured with an optek filter photometer. T = %
Transmission
Deviation of linearity Deviation of the real measurement from
the theoretical linear corre-lation.
Double aperture method Method to determine the linearity of a
light measurement. No refer-ence standard required here, therefore
with inherent minimal meas-urement uncertainties.
Expanded uncertainty Standard uncertainty multiplied by coverage
factor k to define inter-val about measurement result, within which
measurements can be confidently asserted to lie. Mostly k=2,
corresponding to 95% of measurements being within the interval
defined.
Full Width at Half Maximum FWHM
Distance between two wavelengths of a transmission curve of an
interference filter, at which transmission values are equal to 50 %
of the peak maximum of this curve.
Integration time Property of a spectrophotometric measurement.
Amount of time, a spectrophotometer looks at the incoming light to
determine an aver-age measurement value.
Mean wavelength Center wavelength between the two wavelengths,
at which trans-mission values reach 50 % of the peak maximum.
NIST National Institute of Standards and Technology, USA
NIST-traceable Measuring results tracing back to a chain of
comparisons to stan-dards approved by NIST are referred to as
NIST-traceable.
OD Optical Density Absorption value standardized to an optical
path length (OPL) of 10 mm. OD can be calculated by dividing
absorption by OPL in centi-metres.
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Optical path length (OPL) Distance that light passes through a
sample.
Peak wavelength Wavelength, at which transmission curve of an
interference filter reaches its maximum.
Photometric accuracy Accuracy with which a measurement of two
photocurrents and the calculation of its relationship with respect
to its logarithm is carried out.
Process photometer Measuring system for absorption /
transmission, which measures at fix wavelength(s). Used directly in
the process line.
PTB Physikalisch-Technische-Bundesanstalt, Braunschweig.
National metrology institute in Germany.
Sensor adaptation Factor used to adjust measurement result of a
measuring function. Function of optek C4000 converter.
Slit height Property of a spectrophotometric measurement that
affects geome-try and intensity of the light beam.
Slit width Property of a spectrophotometric measurement defining
spectral resolution.
Spectral accuracy Accuracy with which the set wavelength of a
spectrophotometer corresponds to the target wavelength.
Spectrophotometer / Spectrometer
Apparatus measuring absorption / transmission values over a
wave-length range of different wavelengths (simultaneously or
succes-sively). Designed usually for laboratory use.
SRM Standard Reference Material CRM issued under the NIST
trademark.
Tolerance / uncertainty Region about a measurement value, which
is likely to enclose the true (correct) value.
Traceability Property of a measurement result relating the
result to a stated met-rological reference through an unbroken
chain of calibrations of a measuring system or comparisons, each
contributing to the stated measurement uncertainty.
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10. Spare parts
Calibration filters and cuvettes VIS-L0.45 1442-0025-0223-13
VIS-L0.9 1442-0025-0223-23 VIS-L1.8 1442-0025-0223-33 NIR-L0.45
1442-0025-0213-13 NIR-L0.9 1442-0025-0213-23 NIR-L1.8
1442-0025-0213-33 FH03 calibration cuvette 1448-0102-0000-03
Recertifications Recertification VIS-L 1452-0600-1000-03
Recertification NIR-L 1452-0500-1000-03
Accessories and spare parts Case for 7 filter boxes
1450-1000-0000-00 Set stoppers for calibration cu-vette (10
pieces)
1206-0010-4840-86
O-Ring set 2.00 x 1.00 Viton (20 pieces) 1203-0020-0050-02
O-Ring set 18.77 x 1.78 Viton (4 pieces) 1203-0004-0013-02
Screw set M3 x 10 DIN7985 (10 pieces) 1206-0010-0058-01
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11. Appendix
11.1. Declaration of decontamination
For the safety of our employees and because of legal regulations
we need a signed declaration of decontamination before your return
can be handled. This signed declaration must be included with the
shipping documents on the outside of the packaging. Any returns
which were exposed to hazardous substances and were not
professionally decontaminated are not accepted and will be sent
back on your cost. opteks declaration of decontamination and
contact information can be found on our website www.optek.com.
11.2. Disposal
Special legal regulations apply to the return and disposal of
industrial waste equipment. However, manufacturer and user can
contractually agree on which party is to fulfil these legal
obligations. Observe current national disposal regulations. To
dispose packaging material, please separate materials into the
following groups:
Paper / paperboard Plastic
For disposal, disassemble the system components and separate
them according to different material groups. Dispose of materials
according to national and local regulations. If no agreement has
been made, products may be shipped to optek for disposal.
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11.3. Sample certificate for VIS-L090 Calibration Filter
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11.4. Contacts
For further inquiry, feel free to contact us or our distributing
partners at any time:
Germany optek-Danulat GmbH Emscherbruchallee 2 45356 Essen /
Germany Phone: +49-(0)201-63409-0 Fax: +49-(0)201-63409-999 E-Mail:
[email protected] China optek-Danulat Shanghai Co., Ltd Room 718
Building 1 No. 88 Keyuan Road Pudong Zhangjiang Shanghai, China
201203 Phone: +86 21 2898 6326 Fax: +86 21 2898 6325 E-Mail:
[email protected] Singapore optek-Danulat Pte. Ltd. 25 Intl
Business Park #02-09-f German Centre Singapore 609916 Phone: +65
6562 8292 Fax: +65 6562 8293 E-Mail: [email protected]
USA optek-Danulat Inc. N118 W18748 Bunsen Drive Germantown WI
53022 / USA Phone: +1 262 437 3600 Toll free call: +1 800 371 4288
Fax: +1 262 437 3699 E-Mail: [email protected]
88
718
:201203
:+86-21-28986326
:+86-21-28986325 E-Mail: [email protected]
Please visit our website for contact details of our local
distributors in other countries.
www.optek.com