JJF 1187-2008 PDF in English
JJF 1187-2008 (JJF1187-2008) PDF English
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Calibration Specification for Thermal Imagers
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JJF 1187-2008: PDF in English JJF 1187-2008
NATIONAL METROLOGICAL TECHNICAL SPECIFICATIONS
OF THE PEOPLE’S REPUBLIC OF CHINA
Calibration Specification for Thermal Imagers
ISSUED ON: JANUARY 31, 2008
IMPLEMENTED ON: APRIL 30, 2008
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine
Table of Contents
1 Scope ... 5
2 Normative References ... 5
3 Terms and Metrological Unit ... 5
3.1 Terms ... 5
3.2 Metrological unit ... 5
4 Overview ... 6
5 Metrological Characteristics ... 6
5.1 Appearance ... 6
5.2 Display ... 6
5.3 Error of Indication ... 6
5.4 Temperature measurement consistency ... 7
6 Calibration Conditions ... 7
6.1 Environmental conditions ... 7
6.2 Standards and other equipment ... 7
7 Calibration Items and Methods ... 8
7.1 Calibration items ... 8
7.2 Calibration methods ... 8
8 Expression of Calibration Results ... 12
9 Recalibration Time-Interval ... 13
Appendix A Evaluation on the Uncertainty of Indication Error Calibration of
Thermal Imager ... 14
Appendix B Recording Format of Calibration Results ... 18
Appendix C Data Page Format of Thermal Imager Calibration Certificate ... 20
Calibration Specification for Thermal Imagers
1 Scope
This Specification is applicable to the calibration of thermal imagers with temperature
measurement function in the range of -20°C ~ 2000°C.
2 Normative References
This Specification quoted the following references:
JJF 1001-1998 General Terms in Metrology and Their Definitions
JJG 1007-2007 Temperature Metrological Terms and Their Definitions
GB/T 19870-2005 Industrial Inspecting Thermal Imagers
JJF 1059-1999 Evaluation and Expression of Uncertainty in Measurement
When using this Specification, pay attention to adopting the current effective editions
of the above normative references.
3 Terms and Metrological Unit
3.1 Terms
3.1.1 The terms and definitions given in GB/T 19870-2005 Industrial Inspecting
Thermal Imagers are applicable to this Specification.
3.1.2 Error of indication
The error of indication for the thermal imager refers to the difference between the
temperature indication of the thermal imager and the agreed true value of the
measured blackbody radiation source temperature.
3.2 Metrological unit
The temperature unit is Celsius (°C) or Kelvin (K).
The temperature of the blackbody radiation source is usually measured by a contact
thermometer or a radiation thermometer, such as a platinum resistance thermometer
or a thermocouple (with corresponding electrical measuring equipment).
6.2.3 The external display displaying the measurement results of the thermal imager
shall meet the requirements for the measurement signal output index of the calibrated
thermal imager (for example, the external display required by the calibrated thermal
imager).
6.2.4 Instrument holder required for thermal imager calibration.
7 Calibration Items and Methods
7.1 Calibration items
7.1.1 Appearance
The thermal imager's housing, mechanical adjustment parts, exposed optical
components, keys, electrical connections, etc. shall not have defects that affect the
measurement function of the thermal imager.
The camera shall be marked with the manufacturer (or trademark), model, and number,
etc.
7.1.2 Display
There shall be no defects in the display effect of the thermal imager that affect normal
use.
7.1.3 Error of indication
Calibrate the error of indication for the thermal imager under laboratory environmental
conditions.
7.1.4 Temperature measurement consistency
The thermal imager shall be tested for temperature measurement consistency under
laboratory environmental temperature and humidity conditions.
7.2 Calibration methods
7.2.1 Appearance
Take manual and visual inspection, the appearance of the calibrated thermal imager
must meet the requirements of 7.1.1.
7.2.2 Display
Take manual and visual inspection, the display device of the calibrated thermal imager
must meet the requirements of 7.1.2.
7.2.3 Error of indication
7.2.3.1 Selection of calibration temperature point.
The selection of the calibration temperature point is the upper and lower limits of the
range and the middle value of the range. For thermal imager with multiple ranges, in
the temperature range where the ranges overlap, different ranges shall be chosen to
calibrate. At the same time, the calibration temperature can be set according to user
requirements.
7.2.3.2 Clean the exposed optical components of the thermal imager according to the
instructions of the it.
7.2.3.3 Install optical elements such as additional optical lenses or attenuators
according to user requirements.
7.2.3.4 Determine the measurement distance according to the requirements of the
user or the focusing range of the thermal imager, the optical resolution and the target
diameter of the blackbody radiation source. Adjust the position of the thermal imager,
make the thermal imager aim at the target center of the blackbody radiation source in
the axial direction of the blackbody radiation source, and make the measured object
clearly imaged.
7.2.3.5 According to the instruction manual of the thermal imager, turn on the thermal
imager for a certain period of time before measurement (if required by the calibrated
thermal imager).
7.2.3.6 According to the instruction manual of the thermal imager, enter the range and
calibration condition data, such as the ambient temperature, ambient humidity, and
measurement distance parameters. During calibration, the emissivity parameter of the
calibrated thermal imager is set to be 1 or equal to the emissivity of the blackbody
radiation source.
7.2.3.7 Before performing the calibration on the error of indication, other operations
that have an impact on the measurement results, such as clearing, etc. (if required by
the calibrated thermal imager) shall be completed, as required by the instruction
manual of the thermal imager.
7.2.3.8 Refer to the instruction manual and place the calibrated thermal imager in the
point temperature measurement mode to measure the target center temperature of the
blackbody radiation source. Make no less than 4 measurements at each calibration
temperature point. During the measurement, record the measured value, tBBi,j, of the
reference standard of the blackbody radiation source, indication, ti,j, of the calibrated
format of calibration certificate.
In addition to the above calibration result information, the calibration certificate or report
for calibration results shall also include (but not limited to) the following information:
a) A title, such as "calibration certificate" or "calibration report";
b) Laboratory name and address;
c) Where calibration is performed (if calibration is not performed in a laboratory);
d) The unique identification of the certificate or report (such as the certificate
number), the identification of the page number and the total number of pages;
e) The name and address of the calibration-sending organization;
f) The description and clear identification of the calibrated object;
g) The date of the calibration, if it is related to the validity and application of the
calibration results, the date of receipt of the calibrated object shall be stated;
h) The sampling procedures shall be explained if they are relevant to the validity
and application of the calibration results;
i) Identification of the technical specifications on which the calibration is based,
including name and code;
j) A traceability and validity statement of the measurement standards used in this
calibration;
k) A description of the calibration environment;
l) Description of the uncertainty for calibration results and their measurement;
m) The signature, title or equivalent identification of the person who issued the
calibration certificate or report, and the date of issuing;
n) A statement that the calibration result is valid only for the calibrated object;
o) Statements of calibration certificates or reports may not be reproduced in part
without written approval from the laboratory.
9 Recalibration Time-Interval
The time interval for recalibration is determined by the user according to the use
situation, and it is recommended to be 1 year. It shall be shortened appropriately when
it is used frequently.
At 100°C, the emissivity of the blackbody radiation source is 0.9985 ± 0.0015, take
0.9985 as the reference value, correct the indication of calibrated thermal imager
affected by the deviation from 1 of the radiation source emissivity; the radiation
temperature uncertainty of the blackbody source radiation caused by uncertainty
of 0.0015 of the blackbody source emissivity is 0.1°C, which is evaluated as
uniform distribution. The standard uncertainty component caused by the emissivity
correction of the blackbody radiation source u2=0.06°C.
Standard uncertainty component, u3, introduced by reference standard passing
According to the verification certificate, the standard uncertainty component
introduced by precision platinum resistance thermometer u3 = 0.04°C.
Standard uncertainty component, u4, introduced by electrical measurement
equipment
Use the digital multimeter, standard resistance and low pyroelectric four-wire
transfer switch to measure the resistance of standard thermometer. Take Keithley
2000 as an example, the standard uncertainty component introduced by the
electrical measurement equipment u4 = 0.02°C.
Uncertainty component, u5, caused by the temperature difference between the
target surface temperature of the radiation source and the measurement point of
the standard instrument
The temperature difference between the target surface temperature of the radiation
source and the measurement point of the standard instrument is determined by the
characteristics of the temperature field of the radiation source. The maximum
temperature difference between the target surface temperature of the radiation
source and the measurement point of the standard instrument is 0.05°C.
Considering the uniform distribution, its standard uncertainty component u5 =
Then standard uncertainty, u(tBBi), of the input quantity of tBBi is as follows:
A.2.1.2 Evaluation of the standard uncertainty, u(ti), of the input quantity of ti
Standard uncertainty component, u6, introduced by thermal imager measurement
repeatability
The maximum difference among the four measurements of the thermal imager
repeatability experiment is 1.0°C; and the standard deviation of the average value
is u6=(1.0/C/ °C), where the number of measurements is 4, the range coefficient
C = 2.06.
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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