ISO 22013:2021

INTERNATIONAL ISO
STANDARD 22013
First edition
2021-01
Marine environment sensor
performance — Specifications,
testing and reporting — General
requirements
Navires et technologie maritime — Performances des capteurs marins
Reference number
©
ISO 2021
© ISO 2021
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ii © ISO 2021 – All rights reserved

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3  Terms and definitions . 1
4  Specifications .14
4.1 General .14
4.2 Calibration .14
4.3 Range .15
4.3.1 Calibrated range .15
4.3.2 Measuring range.15
4.3.3 Maximum range .15
4.4 Accuracy .15
4.5 Resolution .15
4.6 Response time.15
4.7 Depth and pressure .15
4.7.1 Maximum depth rating .15
4.7.2 Crush depth rating . . .15
4.8 Sample rate .15
4.9 Mechanical .15
4.9.1 Wetted materials .15
4.9.2 Exterior dimensions.16
4.9.3 Mass or weight in air .16
4.9.4 Weight in freshwater .16
4.9.5 Weight in seawater . .16
4.9.6 Operating temperature range .16
4.10 Electrical .16
4.10.1 Input voltage range .16
4.10.2 Operating power consumption .17
4.10.3 Startup power consumption .17
4.11 Interface .17
4.11.1 Electrical connections .17
4.11.2 Communications protocol.17
4.12 Stability .17
4.13 Shelf-life .18
5 Test methods .18
5.1 Overview .18
5.2 General experimental design .18
5.2.1 General.18
5.2.2 Sensor settings.18
5.2.3 Reference .18
5.2.4 Re-calibration .18
5.3 Calibration .18
5.3.1 General.18
5.3.2 Calibration method .19
5.3.3 Experimental design — Layout of the calibration .19
5.3.4 Calibration curve .19
5.3.5 Post-calibration operations .20
5.4 Accuracy .20
5.4.1 General.20
5.4.2 Modifications to ISO 5725 .20
5.4.3 Statistical model .21
5.4.4 Determination of precision .21
5.4.5 Experimental design — Layout of the precision experiment .22
5.4.6 Reference .23
5.4.7 Determination of trueness (bias) .23
5.4.8 Statistical analysis . .23
5.5 Resolution .23
5.5.1 General.23
5.5.2 Experimental design .24
5.5.3 Calculation of s . .24
noise
5.5.4 Calculation of s .24
noise
ij
5.6 Response time.24
5.6.1 General.24
5.6.2 Experimental design .24
5.6.3 Response curve .25
5.7 Depth and pressure .26
5.7.1 Maximum depth rating .26
5.7.2 Crush depth rating . . .27
5.7.3 Pressure case void .27
5.8 Mechanical .27
5.8.1 Wetted materials .27
5.8.2 Weight in freshwater .27
5.8.3 Weight in seawater . .28
5.8.4 Operating temperature range .28
5.9 Electrical .28
5.9.1 Input voltage range .28
5.9.2 Operating power consumption .28
5.9.3 Startup power consumption .29
5.10 Interface .29
5.10.1 General.29
5.10.2 Power on/standby .29
5.10.3 Galvanic isolation test . .29
5.11 Stability .29
5.11.1 General.29
5.11.2 Experimental design .29
5.11.3 Calculation of d .30
5.11.4 Field stability .31
5.12 Shelf-life .31
5.12.1 General.31
5.12.2 Experimental design .31
5.12.3 Calculation of d .31
6 Publication .31
6.1 General .31
6.2 Data sheets .32
6.2.1 General.32
6.2.2 Test reports.33
6.3 Calibration certificates .33
Annex A (informative) Determination of the accuracy (precision and trueness) — Example .35
Annex B (informative) Determination of the response time — Examples .39
Annex C (informative) Data sheet for a sound velocity sensor — Example .43
Bibliography .44
iv © ISO 2021 – All rights reserved

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2. www .iso .org/ directives
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received. www .iso .org/ patents
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
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expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 8, Ships and marine technology,
Subcommittee SC 13, Marine technology.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
Introduction
Oceans are intertwined with many of humanity’s priorities, including trade, food, energy, climate
and security. Understanding what’s going on below the sea surface is important for making decisions
around maritime boundaries, exploiting energy and mineral resources, expanding waterways, and
monitoring aquaculture. All depend on the availability of data produced by marine environment sensors
that measure physical, ecological and chemical parameters of seawater, such as salinity, temperature,
oxygen, carbon dioxide and acidity.
As an example of the growing importance of these data, marine business is increasingly mandated
by law to record them to meet environmental regulations. But common definitions for even basic
performance specifications of these sensors, such as accuracy or stability, don't exist. This weakens
the utility of the laws and diminishes confidence in sensor performance. It also acts to dampen the
market forces driving sensor innovation, as it is difficult for end-users to compare and reward true
breakthroughs from existing manufacturers, or to trust new entrants. This document aims to address
this by establishing a set of performance specifications common to all marine environment sensors,
including terms, definitions and test methods.
vi © ISO 2021 – All rights reserved

INTERNATIONAL STANDARD ISO 22013:2021(E)
Marine environment sensor performance — Specifications,
testing and reporting — General requirements
1 Scope
This document defines terms, specifies test methods and provides reporting requirements for marine
sensor specifications to ensure a consistent reporting by manufacturers.
It is applicable to those devices known as conductivity-temperature-depth (CTDs), sound velocity
probes, multi-parameter sondes and dissolved gas sensors, that measure parameters such as
conductivity, temperature, pressure, sound speed, dissolved oxygen, turbidity, pH, and chlorophyll in
seawater.
It is also generally applicable to all marine environment instruments.
NOTE 1 A ‘CTD’ directly measures conductivity, temperature, and pressure. Depth is derived from pressure
using an equation.
NOTE 2 The term ‘sound velocity probe’ is widely used to describe instruments that measure sound speed. In
this document the term ‘sound velocity’ is used when describing the type of sensor, and the term ‘sound speed’ is
used when describing the parameter or measurand, but these terms can be used interchangeably.
2 Normative references
The following documents are referred to in the text in such a way that some or all their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 5725-2:2019, Accuracy (trueness and precision) of measurement methods and results — Part 2: Basic
method for the determination of repeatability and reproducibility of a standard measurement method
ISO/IEC 17025:2017, General requirements for the competence of testing and calibration laboratories
3  Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
quantity
parameter
property of a phenomenon, body, or substance, where the property has a magnitude that can be
expressed as a number and a reference
Note 1 to entry: A reference can be a measurement unit, a measurement procedure, a reference material, or a
combination of such.
EXAMPLE Pressure, P
[SOURCE: ISO/IEC Guide 99:2007, 1.1, modified — The admitted term “parameter” has been added.
All Notes have been removed except Note 2 to entry, renumbered as Note 1 to entry. The Example has
been added.]
3.2
derived quantity
quantity (3.1) that has been calculated from one or more measurements of other quantities
[8]
EXAMPLE Absolute salinity, S , is calculated from conductivity, temperature and pressure (IOC 56:2010) .
A
3.3
quantity value
value
number and reference together, expressing magnitude of a quantity (3.1)
EXAMPLE 1 Conductivity of a volume of seawater: 35 mS/cm or 3, 5 S/m
EXAMPLE 2 Sound speed of a volume of seawater: 1 500 m/s
[SOURCE: ISO/IEC Guide 99:2007, 1.19, modified — All Examples and Notes have been removed. New
Examples 1 and 2 have been added.]
3.4
measurand
quantity (3.1) intended to be measured
Note 1 to entry: The specification of a measurand requires knowledge of the kind of quantity, description of the
state of the phenomenon, body, or substance carrying the quantity, including any relevant component, and the
chemical entities involved.
Note 2 to entry: In the second edition of the VIM and in IEC 60050-300:2001, the measurand is defined as the
'particular quantity subject to measurement'.
Note 3 to entry: The measurement, including the measuring system and the conditions under which the
measurement is carried out, might change the phenomenon, body, or substance such that the quantity being
measured may differ from the measurand as defined. In this case, adequate correction is necessary.
EXAMPLE 1 The conductivity of a volume of seawater with the ambient Celsius temperature of 23 °C will be
different from the conductivity at the specified temperature of 20 °C, which is the measurand. In this case, a
correction is necessary.
EXAMPLE 2 The length of a steel rod in equilibrium with the ambient Celsius temperature of 23 °C will be
different from the length at the specified temperature of 20 °C, which is the measurand. In this case, a correction
is necessary.
[SOURCE: ISO/IEC Guide 99:2007, 2.3, modified — Note 4 has been removed. Example 2 has been
changed.]
3.5
measurement
process of experimentally obtaining one or more quantity values (3.3) that can reasonably be attributed
to a quantity (3.1)
[SOURCE: ISO/IEC Guide 99:2007, 2.1, modified — All Notes have been removed.]
3.6
measurement unit
unit
real scalar quantity (3.1), defined and adopted by convention, with which any other quantity of the same
kind can be compared to express the ratio of the two quantities as a number
Note 1 to entry: Measurement units are designated by conventionally assigned names and symbols.
2 © ISO 2021 – All rights reserved

Note 2 to entry: Measurement units of quantities of the same quantity dimension may be designated by the
same name and symbol even when the quantities are not of the same kind. For example, joule per kelvin and
J/K are respectively the name and symbol of both a measurement unit of heat capacity and a measurement
unit of entropy, which are generally not considered to be quantities of the same kind. However, in some cases
special measurement unit names are restricted to be used with quantities of a specific kind only. For example,
the measurement unit ‘second to the power minus one’ (1/s) is called hertz (Hz) when used for frequencies and
becquerel (Bq) when used for activities of radionuclides.
EXAMPLE 1 meters per second (m/s)
EXAMPLE 2 millisiemens percentimetre (mS/cm).
EXAMPLE 3 degrees Celsius (°C).
[SOURCE: ISO/IEC Guide 99:2007, 1.9, modified — Notes 3 and 4 have been removed. The Examples
have been added.]
3.7
measurement principle
principle of measurement
phenomenon serving as a basis of a measurement (3.5)
EXAMPLE 1 Thermoelectric effect applied to the measurement of temperature.
EXAMPLE 2 Photoluminescence effect applied to the measurement of dissolved oxygen.
[SOURCE: ISO/IEC Guide 99:2007, 2.4, modified — All original Examples and Notes have been removed.
New Examples 1 and 2 have been added.]
3.8
measurement result
set of quantity values (3.3) being attributed to a measurand (3.4) together with any other available
relevant information
Note 1 to entry: A measurement result generally contains “relevant information” about the set of quantity values,
such that some may be more representative of the measurand than others. This may be expressed in the form of
a probability density function (PDF).
Note 2 to entry: A measurement result is generally expressed as a single measured quantity value and a
measurement uncertainty. If the measurement uncertainty is considered negligible for some purpose, the
measurement result may be expressed as a single measured quantity value. In many fields, this is the common
way of expressing a measurement result.
[SOURCE: ISO/IEC Guide 99:2007, 2.9, modified — Note 3 has been removed.]
3.9
measurement accuracy
closeness of agreement between a measured quantity value and a true quantity value of a measurand (3.4)
Note 1 to entry: The concept "measurement accuracy" is not a quantity and is not given a numerical quantity
value. A measurement is said to be more accurate when it offers a smaller measurement error.
Note 2 to entry: The term "measurement accuracy" should not be used for measurement trueness and the term
"measurement precision" should not be used for 'measurement accuracy', which, however, is related to both
these concepts.
Note 3 to entry: "Measurement accuracy" is sometimes understood as closeness of agreement between measured
quantity values that are being attributed to the measurand.
Note 4 to entry: The admitted term “accuracy” has been removed to reduce ambiguation between the concept of
‘measurement accuracy’ described in ISO/IEC Guide 99, and the method for calculating a marine environment
sensor’s datasheet accuracy as described in 5.4.
[SOURCE: ISO/IEC Guide 99:2007, 2.13, modified — The admitted term “accuracy” has been removed.
Note 4 has been added.]
3.10
measurement trueness
trueness
closeness of agreement between the average of an infinite number of replicate measured quantity
values and a reference quantity value
Note 1 to entry: Measurement trueness is not a quantity and thus cannot be expressed numerically, but measures
for closeness of agreement are given in ISO 5725.
Note 2 to entry: Measurement trueness is inversely related to systematic measurement error, but is not related to
random measurement error.
Note 3 to entry: “Measurement accuracy” should not be used for 'measurement trueness'.
[SOURCE: ISO/IEC Guide 99:2007, 2.14]
3.11
measurement precision
precision
closeness of agreement between indications (3.27) or measured quantity values obtained by replicate
measurements (3.5) on the same or similar objects under specified conditions
Note 1 to entry: Measurement precision is usually expressed numerically by measures of imprecision, such as
standard deviation, variance, or coefficient of variation under the specified conditions of measurement.
Note 2 to entry: The 'specified conditions' can be, for example, repeatability conditions of measurement,
intermediate precision conditions of measurement, or reproducibility conditions of measurement (see
ISO 5725-1:1994).
Note 3 to entry: Measurement precision is used to define measurement repeatability, intermediate measurement
precision, and measurement reproducibility.
Note 4 to entry: Sometimes “measurement precision” is erroneously used to mean measurement accuracy.
[SOURCE: ISO/IEC Guide 99:2007, 2.15]
3.12
measurement error
error
measured quantity value minus a reference quantity value
Note 1 to entry: The concept of 'measurement error' can be used both a) when there is a single reference quantity
value to refer to, which occurs if a calibration is made by means of a measurement standard with a measured
quantity value having a negligible measurement uncertainty or if a conventional quantity value is given, in which
case the measurement error is known, and b) if a measurand is supposed to be represented by a unique true quantity
value or a set of true quantity values of negligible range, in which case the measurement error is not known.
Note 2 to entry: Measurement error should not be confused with production error or mistake.
[SOURCE: ISO/IEC Guide 99:2007, 2.16]
3.13
systematic measurement error
component of measurement error (3.12) that in replicate measurements (3.5) remains constant or varies
in a predictable manner
Note 1 to entry: A reference quantity value for a systematic measurement error is a true quantity value, or a
measured quantity value of a measurement standard of negligible measurement uncertainty, or a conventional
quantity value.
4 © ISO 2021 – All rights reserved

Note 2 to entry: Systematic measurement error, and its causes, can be known or unknown. A correction can be
applied to compensate for a known systematic measurement error.
Note 3 to entry: Systematic measurement error equals measurement error minus random measurement error.
[SOURCE: ISO/IEC Guide 99:2007, 2.17, modified — The admitted term “systematic error” has been
removed.]
3.14
measurement bias
bias
estimate of a systematic measurement error (3.13)
[SOURCE: ISO/IEC Guide 99:2007, 2.18]
3.15
repeatability condition of measurement
repeatability condition
condition of measurement, out of a set of conditions that includes the same measurement procedure,
same operators, same measuring system, same operating conditions and same location, and replicate
measurements (3.5) on the same or similar objects over a short period of time
[SOURCE: ISO/IEC Guide 99:2007, 2.20, modified — The Notes have been removed.]
3.16
intermediate precision condition of measurement
intermediate precision condition
condition of measurement, out of a set of conditions that includes the same measurement procedure,
same location, and replicate measurements (3.5) on the same or similar objects over an extended period
of time, but may include other conditions involving changes
Note 1 to entry: The changes can include new calibrations, calibrators, operators, and measuring systems.
[SOURCE: ISO/IEC Guide 99:2007, 2.22, modified — Notes 2 and 3 have been removed.]
3.17
reproducibility condition of measurement
reproducibility condition
condition of measurement, out of a set of conditions that includes different locations, operators,
measuring systems, and replicate measurements (3.5) on the same or similar objects
[SOURCE: ISO/IEC Guide 99:2007, 2.24, modified — The Notes have been removed.]
3.18
level of the test in a precision experiment
level
average of measurements (3.5) from all sensors (3.45) for one reference material or measurement
standard
[SOURCE: ISO 5725-1:1994, 3.3, modified — The admitted term "level" has been added. The definition
has been adapted.]
3.19
cell of a precision experiment
cell
measurement result (3.8) at a single level (3.18) obtained by one sensor (3.45)
[SOURCE: ISO 5725-1:1994, 3.4, modified — The admitted term "cell" has been added. The definition
has been adapted.]
3.20
measurement uncertainty
uncertainty
non-negative parameter characterizing the dispersion of the quantity values (3.3) being attributed to a
measurand (3.4), based on the information used
Note 1 to entry: Measurement uncertainty includes components arising from systematic effects, such as
components associated with corrections and the assigned quantity values of measurement standards, as well
as the definitional uncertainty. Sometimes estimated systematic effects are not corrected for but, instead,
associated measurement uncertainty components are incorporated.
Note 2 to entry: The parameter may be, for example, a standard deviation called standard measurement
uncertainty (or a specified multiple of it), or the half-width of an interval, having a stated coverage probability.
Note 3 to entry: Measurement uncertainty comprises, in general, many components. Some of these may be
evaluated by Type A evaluation of measurement uncertainty from the statistical distribution of the quantity
values from series of measurements and can be characterized by standard deviations. The other components,
which may be evaluated by Type B evaluation of measurement uncertainty, can also be characterized by standard
deviations, evaluated from probability density functions based on experience or other information.
Note 4 to entry: In general, for a given set of information, it is understood that the measurement uncertainty is
associated with a stated quantity value attributed to the measurand. A modification of this value results in a
modification of the associated uncertainty.
[SOURCE: ISO/IEC Guide 99:2007, 2.26]
3.21
standard measurement uncertainty
standard uncertainty
measurement uncertainty (3.20) expressed as a standard deviation
[SOURCE: ISO/IEC Guide 99:2007, 2.30]
3.22
combined standard uncertainty
combined uncertainty
standard uncertainty of the result of a measurement when that result is obtained from the values of a
number of other quantities (3.1), equal to the positive square root of a sum of terms, the terms being the
variances or covariances of these other quantities weighted according to how the measurement result
(3.8) varies with changes in these quantities
[SOURCE: ISO/IEC Guide 98-3:2008, 2.3.4, modified — The admitted term “combined uncertainty” has
been added.]
3.23
calibration
operation that establishes a relation between the quantity values (3.3) and corresponding indications
(3.27) of a sensor (3.45)
Note 1 to entry: A calibration may be expressed by a statement, calibration function, calibration diagram,
calibration curve, or calibration table. In some cases, it may consist of an additive or multiplicative correction of
the indication with associated measurement uncertainty.
Note 2 to entry: Calibration should not be confused with adjustment of a measurement system, often mistakenly
called “self-calibration”, nor with verification of the calibration.
Note 3 to entry: Often, the step of conducting the operation to establish a relation between quantity values and
corresponding sensor indications alone is already perceived as being calibration.
[SOURCE: ISO/IEC Guide 99:2007, 2.39, modified — The definition has been truncated for clarity.]
6 © ISO 2021 – All rights reserved

3.24
influence quantity
quantity (3.1) that, in a direct measurement, does not affect the quantity that is actually measured, but
affects the relation between the indication (3.27) and the measurement result (3.8)
EXAMPLE Temperature of the sound velocity sensor, but not the temperature of the surrounding seawater
which would enter into the definition of the measurand.
Note 1 to entry: An indirect measurement involves a combination of direct measurements, each of which may be
affected by influence quantities.
Note 2 to entry: In the GUM, the concept “influence quantity” is defined as in the second edition of the VIM,
covering not only the quantities affecting the measuring system, as in the definition above, but also those
quantities that affect the quantities actually measured. Also, in the GUM this concept is not restricted to direct
measurements.
[SOURCE: ISO/IEC Guide 99:2007, 2.52, modified — The original Examples have been removed, and a
new Example has been added.]
3.25
measuring system
set of one or more measuring instruments (3.47) and often other devices, including any reagent and
supply, assembled and adapted to give information used to generate measured quantity values within
specified intervals for quantities of specified kinds
Note 1 to entry: A measuring system may consist of only one measuring instrument.
[SOURCE: ISO/IEC Guide 99:2007, 3.2]
3.26
adjustment of a measuring system
adjustment
set of operations carried out on a measuring system so that it provides prescribed indications (3.27)
corresponding to given values (3.3) of a quantity (3.1) to be measured
Note 1 to entry: Types of adjustment of a measuring system include zero adjustment of a measuring system,
offset adjustment, and span adjustment (sometimes called gain adjustment)
Note 2 to entry: Adjustment of a measuring system should not be confused with calibration, which is a
prerequisite for adjustment.
Note 3 to entry: After an adjustment of a measuring system, the measuring system must usually be recalibrated.
[SOURCE: ISO/IEC Guide 99:2007, 3.11]
3.27
indication
signal
quantity value (3.3) provided by a sensor (3.45) or instrument (3.47)
Note 1 to entry: An indication may be presented in visual or acoustic form or may be transferred to another
device. An indication is often given by the position of a pointer on the display for analogue outputs, a displayed
or printed number for digital outputs, a code pattern for code outputs, or an assigned quantity value for material
measures.
Note 2 to entry: An indication and a corresponding value of the quantity being measured are not necessarily
values of quantities of the same kind.
[SOURCE: ISO/IEC Guide 99:2007, 4.1, modified — The admitted term “signal” has been added. In the
definition, the words “measuring instrument or a measuring system” have been replaced with “sensor
or instrument”.]
3.28
indication range
range
set of quantity values (3.3) bounded by extreme possible indications (3.27)
Note 1 to entry: An indication range is usually stated in terms of its smallest and greatest quantity values, for
example “0 mS/cm to 100 mS/cm”.
[SOURCE: ISO/IEC Guide 99:2007, 4.3, modified — The original term "indication interval" has been
replaced with "indication range" and
...