Industrial process control devices - Radiation thermometers - Part 2: Determination of the technical data for radiation thermometers

IEC/TS 62492-2:2013(E) applies to radiation thermometry and addresses all technical data specified in IEC/TS 62492-1. It defines standard test methods which can be used by the end user of radiation thermometers to determine or confirm the fundamental metrological data of radiation thermometers with one wavelength range and one measurement field. It facilitates comparability and testability. Therefore, unambiguous test methods are stipulated for determining technical data, under standardised measuring conditions that can be performed by a sufficiently skilled end user to serve as standard performance criteria for instrument evaluation or selection.

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Status
Published
Publication Date
24-Apr-2013
Current Stage
PPUB - Publication issued
Start Date
25-Apr-2013
Completion Date
25-Apr-2013
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IEC TS 62492-2:2013 - Industrial process control devices - Radiation thermometers - Part 2: Determination of the technical data for radiation thermometers
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IEC/TS 62492-2
Edition 1.0 2013-04
TECHNICAL
SPECIFICATION
colour
inside
Industrial process control devices – Radiation thermometers –
Part 2: Determination of the technical data for radiation thermometers
IEC/TS 62492-2:2013(E)
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IEC/TS 62492-2
Edition 1.0 2013-04
TECHNICAL
SPECIFICATION
colour
inside
Industrial process control devices – Radiation thermometers –
Part 2: Determination of the technical data for radiation thermometers
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
ICS 17.200.20; 25.040.40 ISBN 978-2-83220-737-6

Warning! Make sure that you obtained this publication from an authorized distributor.

® Registered trademark of the International Electrotechnical Commission
---------------------- Page: 3 ----------------------
– 2 – TS 62492-2 © IEC:2013(E)
CONTENTS

FOREWORD ........................................................................................................................... 4

1 Scope ............................................................................................................................... 6

2 Normative references ....................................................................................................... 6

3 Terms, definitions and abbreviations ................................................................................ 6

3.1 Terms and definitions .............................................................................................. 6

3.2 Abbreviations .......................................................................................................... 9

4 Measurement conditions ................................................................................................... 9

5 Determination of technical data ........................................................................................ 9

5.1 Measuring temperature range .................................................................................. 9

5.1.1 General ....................................................................................................... 9

5.1.2 Test method .............................................................................................. 10

5.2 Measurement uncertainty ...................................................................................... 10

5.2.1 General ..................................................................................................... 10

5.2.2 Test method .............................................................................................. 10

5.3 Noise equivalent temperature difference (NETD) ................................................... 11

5.3.1 General ..................................................................................................... 11

5.3.2 Test method .............................................................................................. 11

5.4 Measuring distance ............................................................................................... 12

5.5 Field-of-view (target size) ...................................................................................... 12

5.5.1 General ..................................................................................................... 12

5.5.2 Test method .............................................................................................. 13

5.6 Distance ratio ........................................................................................................ 14

5.7 Size-of-source effect (SSE) ................................................................................... 14

5.7.1 General ..................................................................................................... 14

5.7.2 Test method .............................................................................................. 14

5.8 Emissivity setting .................................................................................................. 15

5.9 Spectral range ....................................................................................................... 15

5.10 Influence of the internal instrument or ambient temperature (temperature

parameter) ............................................................................................................ 15

5.10.1 General ..................................................................................................... 15

5.10.2 Test method .............................................................................................. 16

5.11 Influence of air humidity (humidity parameter) ....................................................... 17

5.12 Long-term stability ................................................................................................. 17

5.12.1 General ..................................................................................................... 17

5.12.2 Test method .............................................................................................. 17

5.13 Short-term stability ................................................................................................ 18

5.13.1 General ..................................................................................................... 18

5.13.2 Test method .............................................................................................. 18

5.14 Repeatability ......................................................................................................... 18

5.14.1 General ..................................................................................................... 18

5.14.2 Test method .............................................................................................. 19

5.15 Interchangeability .................................................................................................. 19

5.15.1 General ..................................................................................................... 19

5.15.2 Test method .............................................................................................. 19

5.16 Response time ...................................................................................................... 20

5.16.1 General ..................................................................................................... 20

5.16.2 Test method .............................................................................................. 21

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TS 62492-2 © IEC:2013(E) – 3 –

5.17 Exposure time ....................................................................................................... 22

5.17.1 General ..................................................................................................... 22

5.17.2 Test method .............................................................................................. 23

5.18 Warm-up time ........................................................................................................ 24

5.18.1 General ..................................................................................................... 24

5.18.2 Test method .............................................................................................. 24

5.19 Operating temperature and air humidity range ....................................................... 25

5.19.1 General ..................................................................................................... 25

5.19.2 Test method .............................................................................................. 25

5.20 Storage and transport temperature and air humidity range .................................... 26

5.20.1 General ..................................................................................................... 26

5.20.2 Test method .............................................................................................. 26

6 Safety requirement ......................................................................................................... 27

Annex A (informative) Change in indicated temperature of a radiation thermometer

corresponding to a change in the radiation exchange ............................................................ 28

Bibliography .......................................................................................................................... 29

Figure 1 – Relative signal to a signal at a defined aperture size (source size) of

100 mm in diameter for two infrared radiation thermometers A and B versus the source

diameter ............................................................................................................................... 12

Figure 2 – Demonstration of the response time to a rising temperature step ......................... 20

Figure 3 – Possible arrangement for determining the response time with two reference

sources ................................................................................................................................. 22

Figure 4 – Demonstration of the exposure time ..................................................................... 22

Figure 5 – Example of warm-up time ..................................................................................... 25

Table A.1 – The change in indicated temperature corresponding to a 1 % change in the

radiation exchange with a radiation thermometer at 23 °C (Example) .................................... 28

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– 4 – TS 62492-2 © IEC:2013(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL PROCESS CONTROL DEVICES –
RADIATION THERMOMETERS –
Part 2: Determination of the technical data
for radiation thermometers
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

all national electrotechnical committees (IEC National Committees). The object of IEC is to promote

international co-operation on all questions concerning standardization in the electrical and electronic fields. To

this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,

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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

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expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC

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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

indispensable for the correct application of this publication.

9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of

patent rights. IEC shall not be held responsible for identifying any or all such patent rights.

The main task of IEC technical committees is to prepare International Standards. In

exceptional circumstances, a technical committee may propose the publication of a technical

specification when

• the required support cannot be obtained for the publication of an International Standard,

despite repeated efforts, or

• the subject is still under technical development or where, for any other reason, there is the

future but no immediate possibility of an agreement on an International Standard.

Technical specifications are subject to review within three years of publication to decide

whether they can be transformed into International Standards.

IEC 62492-2, which is a technical specification, has been prepared by subcommittee 65B:

Measurement and control devices, of IEC technical committee 65: Industrial-process

measurement, control and automation.
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TS 62492-2 © IEC:2013(E) – 5 –
The text of this technical specification is based on the following documents:
Enquiry draft Report on voting
65B/844/DTS 65B/859/RVC

Full information on the voting for the approval of this technical specification can be found in

the report on voting indicated in the above table.

This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

A list of all parts in the IEC 62492 series, published under the general title Industrial process

control devices – Radiation thermometers, can be found on the IEC website.

The committee has decided that the contents of this publication will remain unchanged until

the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data

related to the specific publication. At this date, the publication will be
• transformed into an International Standard,
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates

that it contains colours which are considered to be useful for the correct

understanding of its contents. Users should therefore print this document using a

colour printer.
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– 6 – TS 62492-2 © IEC:2013(E)
INDUSTRIAL PROCESS CONTROL DEVICES –
RADIATION THERMOMETERS –
Part 2: Determination of the technical data
for radiation thermometers
1 Scope

This part of IEC 62492, which is a Technical Specification, applies to radiation thermometry

and addresses all technical data specified in IEC/TS 62492-1. It defines standard test

methods which can be used by the end user of radiation thermometers to determine or

confirm the fundamental metrological data of radiation thermometers with one wavelength

range and one measurement field.

The purpose of this specification is to facilitate comparability and testability. Therefore,

unambiguous test methods are stipulated for determining technical data, under standardised

measuring conditions that can be performed by a sufficiently skilled end user to serve as

standard performance criteria for instrument evaluation or selection.

It is not compulsory for manufacturers and sellers of radiation thermometers to include all

technical data given in this document in the data sheets for a specific type of radiation

thermometer. Only the relevant data should be stated and should comply with this
specification and IEC/TS 62492-1.
NOTE Infrared ear thermometers are excluded from this Technical Specification.
2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and

are indispensable for its application. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any
amendments) applies.

IEC/TS 62492-1:2008, Industrial process control devices – Radiation thermometers – Part 1:

Technical data for radiation thermometers
3 Terms, definitions and abbreviations
3.1 Terms and definitions
For the purposes of this document the following terms and definitions apply.
NOTE The terms and definitions listed below comply with IEC/TS 62492-1.
3.1.1
measuring temperature range
temperature range for which the radiation thermometer is designed
3.1.2
measurement uncertainty

parameter, associated with the result of a measurement, that characterises the dispersion of

the values that could reasonably be attributed to the measurand
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TS 62492-2 © IEC:2013(E) – 7 –
3.1.3
noise equivalent temperature difference

parameter which indicates the contribution of the measurement uncertainty in °C, which is due

to instrument noise
3.1.4
measuring distance

distance or distance range between the radiation thermometer and the target (measured

object) for which the radiation thermometer is designed
3.1.5
field-of-view

a usually circular, flat surface of a measured object from which the radiation thermometer

receives radiation
3.1.6
distance ratio

the ratio of the measuring distance to the diameter of the field-of-view, when the target is in

focus
3.1.7
size-of-source effect

the difference in the radiance or temperature reading of the radiation thermometer when

changing the size of the radiating area of the observed source
3.1.8
emissivity setting

ratio between the radiation emitted from this surface and the radiation from a blackbody at the

same temperature

Note 1 to entry: In most measuring situations a radiation thermometer is used on a surface with an emissivity

significantly lower than 1. For this purpose most thermometers have the possibility of adjusting the emissivity

setting. The temperature reading is then automatically corrected.
3.1.9
spectral range

parameter which gives the lower and upper limits of the wavelength range over which the

radiation thermometer collects radiation from a source
3.1.10
influence of the internal instrument temperature
influence of the ambient temperature
temperature parameter

parameter which gives the additional uncertainty of the measured temperature value

depending on the deviation of the temperature of the radiation thermometer from the value for

which the technical data is valid after warm-up time and under stable ambient conditions

3.1.11
influence of air humidity
humidity parameter

parameter which gives the additional uncertainty of the measured temperature value

depending on the relative air humidity at a defined ambient temperature
3.1.12
long-term stability
the reproducibility of measurements repeated over a long time period
Note 1 to entry: The time period is typically three months or one year.
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– 8 – TS 62492-2 © IEC:2013(E)
3.1.13
short-term stability
the reproducibility of measurements repeated over a short time period
Note 1 to entry: The time period is several hours.
3.1.14
repeatability

twice the standard deviation of measurements repeated under the same conditions within a

very short time span
Note 1 to entry: The time span is several minutes.
3.1.15
interchangeability

the maximum deviation between the readings of two instruments of the same type operating

under identical conditions divided by two
3.1.16
response time

time interval between the instant of an abrupt change in the value of the input parameter and

the instant from which the measured value of the radiation thermometer remains within

specified limits of its final value

Note 1 to entry: The input parameter is an object temperature or an object radiation, and the output value is an

output parameter.
3.1.17
exposure time

time interval between an abrupt rise and an abrupt fall in the value of the input parameter,

such that the output value of the radiation thermometer reaches a given measurement value

Note 1 to entry: The input parameter is an object temperature or an object radiation.

3.1.18
warm-up time

time period needed for the radiation thermometer, after switching on, before it operates

according to its specifications
3.1.19
operating temperature

the permissible temperature range within which the radiation thermometer may be operated

Note 1 to entry: For this temperature the specifications are valid.
3.1.20
operating air humidity range

the permissible humidity range within which the radiation thermometer may be operated

Note 1 to entry: For this humidity range the specifications are valid.
3.1.21
storage and transport temperature

the permissible ambient temperature range within which the radiation thermometer may be

stored and transported without suffering permanent change
3.1.22
storage and transport air humidity range

the permissible humidity range within which the radiation thermometer may be stored and

transported without suffering permanent change
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TS 62492-2 © IEC:2013(E) – 9 –
3.1.23
safety
freedom from unacceptable risk
3.1.24
risk

combination of the probability of the occurrence of harm and the severity of that harm

3.1.25
harm

physical injury or damage to the health of people, or damage to property or the environment

3.1.26
tolerable risk
risk which is accepted in a given context based on the current values of society
3.2 Abbreviations
FWHM Full width at half maximum
NETD Noise equivalent temperature difference
SSE Size-of-source effect
4 Measurement conditions

The following test conditions apply for all measurements, if not stated otherwise:

a) laboratory ambient temperature range from 18 °C to 28 °C;

b) any special ambient conditions (e.g. humidity range, maximum ambient temperature

change per time) and measurement conditions (e.g. measuring distance, radiating area

diameter, response time) given by the manufacturer for the specific radiation thermometer

to be adhered to;

c) the radiation thermometer to be connected to a power supply in accordance to the

manufacturer’s instructions;
d) the warm-up time specified by the manufacturer to be adhered to;

e) internal standardization check (initial self-test) to be carried out, if available;

f) emissivity setting set to 1 (one), if available;

g) the reference temperature source shall have a radiating area diameter as large as

possible and in any case greater than the radiation thermometer field-of-view (target area)

diameter;

h) all tests have to be performed with the reference temperature source set to a temperature

that is significantly different from ambient temperature and the internal temperature of the

radiation thermometer.

NOTE The reference temperature source is a radiation source of known radiation temperature in the spectral

range of the radiation thermometer. Usually it is a blackbody source realised by a cavity radiator of known

temperature. It will be called “reference source” throughout this document.
5 Determination of technical data
5.1 Measuring temperature range
5.1.1 General

The purpose of this test is to determine the measuring temperature range. For this

temperature range, the measurement uncertainty remains within the specified limits.

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– 10 – TS 62492-2 © IEC:2013(E)

Measurement temperature range (5.1), as well as Measurement uncertainty (5.2) and Noise

equivalent temperature difference (5.3), are the most important parameters that specify a

radiation thermometer. These three parameters are correlated with each other and in general

noise equivalent temperature difference is larger at the lower limit of the measuring

temperature range where uncertainty is larger. This relation is demonstrated in Table A.1 and

the equation of Annex A.

NOTE Sometimes it is useful to determine additionally a wider indicating temperature range over which the

thermometer will display a temperature but its specifications are not guaranteed.

5.1.2 Test method

5.1.2.1 The determination of the measuring temperature range is performed in accordance

with 5.2.2 at the top and the bottom temperature of the specified measuring temperature

range.
Determination of the indicating temperature range:

5.1.2.2 Sight the radiation thermometer at the centre of the radiating area of the reference

source.

5.1.2.3 The temperature of the reference source is sequentially adjusted and stabilised at

temperatures around the minimum temperature and the maximum temperature of the

indicating temperature range given by the manufacturer, to determine the minimum and

maximum temperatures for which the radiation thermometer is still indicating.
5.1.2.4 These two temperatures give the indicating temperature range.
5.2 Measurement uncertainty
5.2.1 General

A detailed description of the different methods to determine the measurement uncertainty and

its confidence level is beyond the scope of this technical specification. In this technical

specification terms, concept and definition of uncertainty is based on ISO/IEC Guide 98-3 and

ISO/IEC Guide 99.

The described method is a basic test of the measurement uncertainty across the measuring

temperature range.
5.2.2 Test method

5.2.2.1 Sight the radiation thermometer at the centre of the radiating area of the reference

source.

5.2.2.2 The temperature of the reference source is sequentially stabilised at, at least, three

temperatures distributed at the top, the bottom and an intermediate temperature of the

measuring temperature range (see Note 1 of 5.2.2.5).

5.2.2.3 The temperature of the reference source and the temperature indicated by the

radiation thermometer are recorded. The difference between these two values is calculated

and recorded.

5.2.2.4 The test sequence is performed three times for the same three calibration points. An

average temperature difference is calculated and recorded for each calibration temperature

point.

5.2.2.5 The value of the measurement uncertainty of the radiation thermometer at each

calibration temperature is taken to be the average difference determined in 5.2.2.4 plus the

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TS 62492-2 © IEC:2013(E) – 11 –

temperature uncertainty of the reference source in respect to the current International

Temperature Scale.
NOTE 1 The numb
...

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