Some standard content:
National Metrology Technical Specification of the People's Republic of China JJF1257-2010
Calibration Guideline of the Temperature Block Calibrators2010-06-10 Issued
Implementation on 2010-09-10
Issued by the General Administration of Quality Supervision, Inspection and Quarantine JJF1257—2010
Calibration Guideline of
the Temperature Block CalibratorsJJF1257-
This specification was approved by the General Administration of Quality Supervision, Inspection and Quarantine on June 10, 2010 and came into effect on September 10, 2010.
Responsible unit: National Technical Committee on Temperature Metrology Drafting unit: China National Institute of Metrology Participating drafting units: AMETEK Beijing Representative Office Beijing Conest Instrument Technology Co., Ltd. Shenzhen Aikang Instrument Technology Co., Ltd. Fluke Corporation of the United States
The provisions of this specification are interpreted by the National Technical Committee on Temperature Metrology Product Partner Network httn: /
Main drafter of this specification:
JJF1257—2010
Zheng Wei (China Institute of Metrology) Institute of Metrology)
Participating drafters:
Wang Yulan (China National Institute of Metrology) Xiang Mingdong (China National Institute of Metrology) Yu Darui (AMETEK Beijing Representative Office) He Xin (Beijing Conster Instrument Technology Co., Ltd.) Lu Xiaoyun (Shenzhen Aiyikang Instrument Technology Co., Ltd.) Chen Yu (Fluke Corporation, USA)
He H Banwei httn://wwr
References
Terms and definitions
Metrological characteristics
Temperature deviation||tt ||Other temperature characteristics of the dry-block furnace
6 Calibration conditions
Thermometer and supporting electrical measuring equipment
Matching bushing
6.3 Environmental conditions I
Calibration items and methods
Calibration items
7.2 Calibration methods·
8 Expression of calibration results
8.1 Calibration report information·
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8.2 Explanation of calibration results and measurement uncertainty Appendix A Uncertainty of dry-block furnace temperature deviation Appendix B Measurement method of factors affecting axial temperature field distribution Appendix C Recommended use of dry block furnace
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Calibration method of dry block temperature calibrator
The calibration method specified in this specification is applicable to the calibration of dry block temperature calibrators (hereinafter referred to as dry block furnaces) with a temperature range of -80℃ to 1300℃. The calibration temperature should not exceed the temperature range given by the dry block furnace manufacturer. 2 References
JJF1071—2000
Rules for Writing National Metrology Calibration Specifications
o1Calibration of TemperaruBiock Calibrators (Calibration of Dry-Block Temperature EURAMET/CG
Calibrator)
Scope of Use
3 Terms and Definitions
3.1 Dry-Block Calibrator
Attention should be paid to the use of the current valid version of the above references. The dry-block calibrator uses the temperature equalization effect of the built-in temperature equalization block to ensure that the calibrated meter inserted into the temperature equalization block maintains the same temperature as the reference standard. 3.2 Bushing The metal bushing placed between the temperature measuring hole of the dry body furnace and the thermometer has good heat conduction. 3.3 Measurement zone The metal bushing should be made of a solid heat-conducting material. The purpose is to make the thermometer and the temperature measuring hole have good heat conduction. The area in the dry body furnace temperature measuring hole used to calibrate the thermometer. Its position is fixed, usually located at the bottom of the temperature measuring hole. If the measurement is at other positions, it should be clearly stated. 4 Overview The dry body furnace is mainly used for the calibration of thermometers. It consists of several parts: a solid temperature-isolating block, a regulating device for controlling the temperature of the temperature-isolating block, a sensor for measuring the temperature of the temperature-isolating block, and a temperature indicator (which can also be displayed by a temperature control meter). These components can be a combined unit or an independent unit with a clear division of labor. The dry-body furnace is small and easy to carry, and has a fast rise and fall speed. It is a relatively stable temperature source with a temperature display, which can provide a reference temperature for on-site calibration. The dry-body furnace provides a relatively stable and uniform temperature measurement area for the calibrated thermometer. The measurement area should have a uniform temperature area of at least 40mm long. The current temperature value can be displayed on its temperature display. The temperature value displayed by the dry-body furnace is usually the temperature value measured by the temperature control sensor. The accuracy and placement of the temperature control sensor will affect the accuracy of the temperature in the measurement area.
Due to the structural characteristics of the dry-body furnace itself, when using a dry-body furnace to calibrate a thermometer, the calibration result is easily affected by factors such as the number, shape and size of the calibration thermometer, the selection of the temperature measurement hole, the calibration environment, and the temperature characteristics of the dry-body furnace itself. When using a dry-body furnace to calibrate a thermometer, the use of the calibration result should take into account the influence of the above factors. In order to reduce the measurement uncertainty of the calibration results, the dry block furnace should be used correctly. Appendix C provides recommended usage methods. 5 Metrological characteristics
5.1 Temperature deviation
Temperature deviation refers to the difference between the displayed temperature of the dry block furnace and the temperature of the measuring area: the calibration results of the dry block furnace should give the temperature deviation and measurement uncertainty
5.2 Other temperature characteristics of the dry block furnace
These important factors need to be considered when evaluating the uncertainty of the calibration results. 5.2.1 Temperature fluctuation
The temperature of the dry block furnace should have good stability over time. 5.2.2 Temperature difference between holes
The maximum temperature difference between different temperature measuring holes in the dry block temperature block. 5.2.3 Axial temperature field uniformity
The uniformity of the temperature distribution along the axial direction of the temperature measuring hole in the measurement area of the dry block temperature block. 5.2.4 Load characteristics
The influence of different loads on the temperature of the measuring area of the dry-body furnace. For the measurement with high measurement uncertainty requirements, the necessary measurement should be carried out. 6 Calibration conditions
6.1 Thermometer and supporting electrical measuring equipment
The expanded uncertainty introduced by the thermometer and the electrical measuring equipment used with it should be as small as possible compared with the technical indicators of the calibrated dry-body furnace.
6.1.1 Requirements for the size of the thermometer
Unless the customer has special requirements, the following measurement conditions should be followed: a) The outer diameter of the thermometer (including the outer protective sleeve) used for calibration should not exceed 6mm, and the insertion depth should be at least 15 times its outer diameter.
b) In the temperature range of -80℃ to 660℃, the maximum difference between the outer diameter of the thermometer used for calibration and the inner diameter of the temperature measuring hole or bushing is 0.5mm; in the temperature range of 660℃ to 1300℃, this value is 1.0mm at most. Close dimensional matching and heat conduction means are conducive to good heat transfer. 6.1.2 Thermometer metrological properties
For temperature deviation measurements and load characteristics, calibrated reference thermometers shall be used and shall be traceable to national temperature standards.
For other temperature characteristics of the dry block, the thermometer shall be used only to measure the temperature difference. Other thermometers of known sensitivity and stability may be used. Their measurements do not need to be calibrated, but their stability shall be tested. 6.2 Matching bushings
If matching bushings are used, they shall be made of the material specified by the manufacturer. If the dry block has one or more holes for matching bushings, they shall meet the manufacturer's technical requirements. The holes for matching bushings shall be measured in the same way as the holes in the dry block without bushings. Matching bushings shall be clearly marked. 2
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6.3 Environmental conditions
Temperature: 15℃~35℃
Humidity: 85%RH
Calibration items and methods
7.1 Calibration items
Temperature deviation
7.1.2 Other temperature characteristics
7.1.2.1 Temperature fluctuation
7.1. 2.2 Temperature difference between holes
Axial temperature field uniformity
Load characteristics
JJF1257—2010
1. For measurements with high uncertainty requirements, the influence of the negative intercept on the temperature of the measuring area should be considered. 2. If the requirements of 6.1.1 for the size of the thermometer cannot be met during calibration, the temperature deviation caused by heat conduction should also be considered when evaluating the uncertainty of the measurement results. The user should calculate the temperature deviation caused by heat conduction when using a dry block for calibration.
7.2 Calibration method
Please note the following when calibrating a dry block: a) If the sensor and display used to measure the temperature of the uniform block need to be calibrated separately, they should meet the corresponding technical indicators.
b) Any adjustments to the equipment should be made before calibration. c) For all measurements except the axial temperature field measurement, the thermometer should be placed at the bottom of the temperature measuring hole of the dry block. 7.2.1 Temperature deviation
7.2.1.1 Use a reference standard thermometer to measure the temperature deviation. 7.2.1.2 The calibration temperature points can be selected according to customer requirements. Usually there should be no less than three temperature points. The calibration points should be selected as close to the upper and lower limits of the dry body temperature range as possible and evenly distributed. 7.2.1.3 The temperature measuring hole should be the center hole or a specially designated hole. 7.2.1.4 Insert the reference standard thermometer into the temperature measuring hole and set the calibration point temperature: After the temperature reaches stability, record the display value of the dry body furnace and the measured value of the reference thermometer respectively. The recording time should not be less than 10 minutes, and the measurement speed is once per minute. Take the average value of the difference between the display value of the dry body furnace and the measured value of the reference thermometer as a measurement result. Take two measurements at each calibration point: When changing the calibration point setting, one measurement should be made when the set temperature rises, and the other measurement should be made when the set temperature drops. If the reference standard thermometer was used to measure the stability of the dry body furnace over time, it is not necessary to repeat the measurement and directly use its data. If the measurement points are selected at the highest and lowest temperature points given by the manufacturer, it is not required to measure the rising or falling set temperature at the highest or lowest point. However, it is necessary to change the set temperature and perform at least two measurements.
7.2.1.5 Calculation
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The temperature deviation of each measurement is calculated according to formula (1): t-
The difference between the dry block temperature display value measured at this calibration temperature point and the temperature of the measurement temperature zone: Where:
The temperature value displayed by the dry block furnace during the first measurement; te
The temperature value measured by the reference thermometer during the second measurement; ta
Number of measurement records.
Set the calibration point at the rising measurement value
At, and calculate according to formula (2):
-measure NH average value as the measurement result A+A of this calibration point
The measurement result should be given in the form of digital diagram or table. 7.2.2 Temperature fluctuation
In the temperature measuring hole of the dry body furnace, when the temperature of the dry body furnace reaches thermal equilibrium (the manufacturer has special provisions to insert the thermometer into the
equilibrium judgment), record the temperature value indicated by the thermometer within min (under the conditions of
, one and a half fluctuation cycles after reaching the set point temperature is measured once every 2min). Take half of the difference between the maximum and minimum values, and add
“±” as the temperature fluctuation of the dry body furnace. The measurement should be made at three different temperature points. If the highest or lowest temperature point is at room temperature, the temperature difference between the holes in Section 7.2.3 is the highest temperature point, the lowest temperature point and the vicinity of room temperature. For example, in the middle. The maximum temperature difference between different temperature measuring holes should be measured at three different temperature points. In order to reduce the influence of temperature drift over time, a temperature gauge can be added during calibration to eliminate the influence of temperature drift. The two farthest relative distances should be selected to measure the temperature difference between the holes. Reference method: Insert two thermometers A and B into two measurement holes, respectively. Read the indications of the two thermometers for the first time, and insert thermometer B into LAh and t. Repeat the above measurement, the temperature difference t between the holes is
Special humidity
holes #a, #b
After the temperature stabilizes +
Exchange the measurement ritual, that is, insert thermometer A
After the temperature stabilizes again, take the indications of the two thermometers for the second time, and measure a total of 4 times:
Ata=(tAai+tBa2+tA+tB)-(tBbi+tA2+tBbs+tAm/47.2.4Axial temperature field uniformity
7.2.4 .1 In the measurement uncertainty of the calibration result, the temperature distribution in the measuring area in the temperature measuring hole (axial temperature field) is considered as a source of measurement uncertainty, which often plays a major role in the measurement uncertainty of the calibration result. Previous research reports on the temperature distribution of the same type of calibrator can be used in the uncertainty assessment. A certain type of thermometer used in the measurement may affect the measurement results of the axial temperature field: this should be negotiated with the customer. 7.2.4.2 The measurement should be made in the center hole or in a specially marked hole. 4
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7.2.4.3 The measurement temperature point should be selected at the temperature point with the largest deviation from the ambient temperature. For the dry block furnace measurement area, which can be heated and cooled at the same time, the measurement should be made at the highest and lowest temperature points. The influence of the temperature distribution on other temperature points can be obtained by linear interpolation. (See Appendix A.3.2 for example) 7.2.4.4 Use a small-sized temperature sensing element for three-point temperature measurement Use a thermometer with a maximum length of 5 mm for the temperature sensing element, and in the measurement area The temperature is measured at the bottom, middle and top. The outer diameter of the thermometer (including the outer protection tube) should not be greater than 6mm. When the measuring temperature range is 80℃ to 250℃: it is recommended to use a platinum resistance thermometer. When the measuring temperature range is 250℃ to 1300℃, it is recommended to use a thermocouple (including Pr-Pd thermocouple). The temperature field is measured from the bottom to the top 40mm long. The following process should be followed: (1) Put the thermometer at the bottom: AS
(2) Lift the thermometer up to 20mmz
Lift to 40mm
（3）Thermometer to
（4）Thermometer placed at the bottom.
7.2.4.5 Other possible methods are shown in Appendix B.
7.2.5 The influence of load on the temperature of the measuring area
For measurements with high uncertainty requirements, the recommended method is to use the difference between the results and the influence of load on the temperature of the measuring area. The necessary measurement should be carried out. The load is measured at the recommended temperature point. A test thermometer is loaded. The measurement result of loading the thermometers in all holes is the effect of the load on the temperature of the measuring area. Metal rods and ceramic rods can be used to simulate loading. The temperature point farthest from the room temperature is selected as the measuring temperature point. Expression of calibration results
8.1 Calibration report information
The calibration report shall contain the following information at least
1 Calibration report
a) Title, such as "Calibration Certificate" or
b) Laboratory name and address:
If the calibration is not performed in the laboratory
c) Location of calibration d) identification of the certificate or report (such as number), identification of each page and the total number of pages; e) name and address of the organization sending the calibration; description and clear identification of the object to be calibrated; g) date of calibration, if it is related to the application of the calibration results, the date of receipt of the object to be calibrated should be stated; h) if it is related to the validity and application of the calibration results, the sampling procedure should be explained; i) identification of the technical documents on which the calibration is based, including Name and code:) Traceability and validity of the reference standard used in this calibration; k) Description of the calibration environment;
1) Description of the calibration result and measurement uncertainty: m) Signature, position or equivalent identification of the issuer of the calibration certificate or calibration report, and the date of issue: n) Statement that the calibration result is only valid for the object being calibrated: 5
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0) Statement that no partial reproduction of the certificate or report is allowed without the written approval of the laboratory. 8.2. Explanation of calibration results and measurement uncertainty 1) Dry block furnace setting value, display value, temperature deviation and measurement uncertainty; 2) Temperature fluctuation:
3) Temperature difference between holes;
4) Axial temperature field uniformity:
5) Load characteristics:
6) Additional instructions for measurement. The judgment conditions for temperature stability should be indicated; the type of thermometer used in the temperature difference between holes and the axial temperature field uniformity, the size of the temperature sensing element and the test method used. If the calibration certificate given uses the previous measurement data and uncertainty components of the same model as the calibrated equipment, it should be noted when issuing the calibration certificate;
7) Put the contents of Appendix C "Recommended use of dry block furnace" in the calibration certificate: 8) In order to check the dry block furnace, it is recommended to use a calibrated thermometer for regular measurement inspection. If the measurement inspection is not carried out using a calibrated thermometer, it is recommended to recalibrate the dry block furnace every year. 6
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A.1 Mathematical model of measurementWww.bzxZ.net
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Uncertainty assessment of dry-block furnace temperature deviation Af=te-t,+8t
Where: t—dry-block furnace temperature deviation:
te—dry-block furnace display temperature;
tTemperature of the measurement area obtained by the reference thermometer:,—deviation caused by the measurement method, means and process. When evaluating the measurement deviation, it is similar to calibrating the thermometer. The sources of uncertainty can be analyzed according to the measurement process. Mainly from the calibration value of the reference thermometer used, the measurement value of the reference thermometer, and the resolution of the supporting electrical measuring equipment. The difference between the temperature rise and fall during measurement (hysteresis band), as well as the uncertainty introduced by other temperature characteristics of the dry-block furnace in the measurement process.
A.2 Uncertainty introduced by the temperature fluctuation of the dry-block furnace The measurement uncertainty component can be estimated using the measurement results of 7.2.2. A.3 Uncertainty introduced by the temperature distribution of the temperature block of the dry-body furnace A.3.1 The temperature distribution of the dry-body furnace cannot be accurately known. The load is different: the stabilization time is different, which causes the temperature displayed on the temperature control table of the dry-body furnace to produce an additional temperature deviation from the measurement area. The area used by the customer may be different from the calibration area (measurement area). Therefore, this additional deviation cannot be corrected. The measurement uncertainty component can be estimated using the measurement results of 7.2.3 and 7.2.4. A3.2 The measurement uncertainty component at the calibration point can be obtained by linearizing the internal difference of the measured value. The uncertainty component close to the room temperature range can be set to a fixed value. For example: calibrate the dry-body furnace, its temperature range is -30℃t200℃. The ambient temperature for calibration is 20°C. The maximum temperature difference is 0.3°C at calibration point 1 = -30°C in the temperature zone: 0.6°C at calibration point 1 - 200°C. In the temperature range 20°C ± 50°C, i.e. in the range 30°C to 70°C, the maximum temperature difference should be given as 0.3°C: In the temperature range 70°C to 200°C: This should correspond to linear internal errors of 0.3°C and 0.6°C. A.4 Uncertainty due to the load effect of the dry block The measurement uncertainty component can be estimated using the measurement results of 7.2.5. A.5 Uncertainty of temperature deviation due to thermal conductivity The measurement uncertainty component of the temperature deviation due to thermal conductivity can be ignored when the outer diameter of the calibrated thermometer is d ≤ 6 mm. If the outer diameter of the calibrated thermometer is 6 mm, the measurement uncertainty should be analyzed separately. If the temperature deviation caused by the heat conduction of the calibrated thermometer can be ignored: when using this dry block furnace to calibrate the measurement uncertainty of the thermometer according to the method specified in its operating manual and calibration certificate, the measurement uncertainty given in the dry block furnace calibration certificate should be quoted.
A6 Example of measurement uncertainty calculation
The following is a calibration of a dry block furnace with a built-in temperature display, with the set temperature being 180°C. A.6.1 When the dry block furnace stably displays 180°C, use a calibrated platinum resistance thermometer as a reference standard and insert it into one of the holes of the dry block furnace. The actual temperature is obtained by measuring the resistance using an AC bridge. A.6.2 When the built-in temperature display is 180°C, the temperature deviation in the hole is △/measured by the mathematical model A=t-t+ot+ap+o+ot+otu+at+ott+aty, where △ is the temperature indication deviation, is the temperature displayed by the dry body furnace, t is the temperature of the temperature measuring hole of the dry body furnace, and t, o,,,ov are the various deviations.
A.6.3 In the calibration: the outer diameter d6mmrm of the reference resistance thermometer used: the influence caused by the heat conduction of the thermometer rod is not considered. Previous studies have shown that the influence caused by the heat conduction of the rod should be ignored under such measurement conditions. A6.4 Actual temperature (t): By checking the calibration certificate of the reference standard resistance thermometer, the measured temperature value is 180.10°C. The expanded uncertainty of the measurement is 0H03N hundred factors k-2). The temperature measured by the reference standard resistance thermometer is 180.10°C. A.6.5 Influence of resistance measurement (o)
The error caused by the electrical measuring equipment is converted into the standard uncertainty of temperature c (8t) = 8o A.6.6 Drift of reference standard (: Based on previous experience, the temperature change caused by the aging of the platinum resistance thermometer used as the reference standard should be within 0.4°C of the temperature setting of the dry body furnace temperature block, and the temperature display table of the temperature controller has a resolution of 0.1°C. The error caused by them is not measured in units of temperature. Note: If the temperature control is not calculated to obtain a relative temperature. A.6.8 Temperature between holes
± 0.05°C, and the temperature is evenly distributed. The error of |tt|| should be calculated by
using the relevant coefficient
(8R): The calibrator has 6 holes. At 180℃, the maximum temperature difference between the temperature measuring holes is 0.07℃. Range:
0.14℃, and the temperature distribution difference between the holes should be uniformly distributed.
A.6.9 Hysteresis effect
: The deviation of the temperature display in the temperature rise and fall measurement cycle
is estimated to be 0.5℃, uniformly distributed.
A6.10 Axial uniformity of temperature (8): The reading difference caused by the different depths caused by the axial temperature unevenness of the dry body furnace hole is estimated to be within ±
5℃, uniformly distributed
Load of uniform temperature block): The influence of the maximum load of the center hole is 0.05℃, uniformly distributed. A. 6.11 Temperature uncertainty (atv): The temperature is uniformly distributed within a temperature change of ±0.03°C. Correlation: The individual inputs in this measurement cycle are uncorrelated. The resolution limit of the temperature meter caused by the temperature stability within the min does not reflect the dispersion of the measured data. Repeatability of measurement: The uncertainty is summarized in Table ICHIN Estimated value NEMETROLOGY Standard uncertainty Sensitivity coefficient u(a)/°C Uncertainty component uCy/°C1. The temperature distribution of the dry-body furnace cannot be accurately known. Different loads and different stabilization times cause the temperature displayed on the temperature control table of the dry-body furnace to produce an additional temperature deviation from the measurement area. The area used by the customer may be different from the calibration area (measurement area). Therefore, this additional deviation cannot be corrected. The measurement uncertainty components can be estimated using the measurement results of 7.2.3 and 7.2.4. A3.2 The measurement uncertainty components at the calibration point can be obtained by linearizing the internal difference of the measured value. In the room temperature range, the uncertainty components can be set to fixed values. For example: calibrate the dry-body furnace, its temperature range is -30℃t200℃. The calibration ambient temperature is 20℃. At the calibration point 1 in the temperature zone, the maximum temperature difference is 0.3℃ when 1=-30℃: The maximum temperature difference is 0.6℃ when 1-200℃. In the temperature range of 20℃±50℃, that is, in the range of 30℃ to 70℃, the maximum temperature difference should be given as 0.3℃: In the temperature range of 70℃ to 200℃: It should correspond to linear internal differences of 0.3℃ and 0.6℃. A.4 Uncertainty due to the load effect of the dry block The measurement uncertainty component can be estimated using the measurement results of 7.2.5. A.5 Uncertainty of temperature deviation due to heat conduction When the outer diameter of the calibrated thermometer is d≤6mm, the measurement uncertainty component of the temperature deviation due to heat conduction can be ignored. If the outer diameter of the calibrated thermometer is 6mm, the measurement uncertainty should be analyzed separately. If the temperature deviation due to heat conduction of the calibrated thermometer can be ignored: When using this dry block to calibrate the measurement uncertainty of the thermometer according to the method specified in its operating manual and calibration certificate, the measurement uncertainty given in the dry block calibration certificate should be quoted.
A6 Example of measurement uncertainty calculation
The following is a calibration of a dry block with a built-in temperature display, set to 180℃. A.6.1 When the dry block furnace stably displays 180°C, a calibrated platinum resistance thermometer is used as a reference standard and inserted into one of the holes of the dry block furnace. The actual temperature is obtained by measuring the resistance using an AC bridge. A.6.2 When the built-in temperature display is 180°C, the temperature deviation in the hole is △/measured by the mathematical model A=t-t+ot+ap+o+ot+otu+at+ott+aty, where △ is the temperature indication deviation, is the dry block furnace display temperature, t is the temperature of the dry block furnace temperature measurement hole, and t, o,,,ov are the various deviations.
A.6.3 In the calibration: the outer diameter d6mmrm of the reference resistance thermometer used: the influence caused by the heat conduction of the thermometer rod is not considered. Previous studies have shown that the effect of heat conduction of the rod should be ignored under such measurement conditions. A6.4 Actual temperature (t): By checking the calibration certificate of the reference standard resistance thermometer, the measured temperature value is 180.10℃. The expanded uncertainty of the measurement is 0H03N (0.03N/ ... A.6.5 Influence of resistance measurement (o)
The error caused by the electrical measuring equipment is converted into the standard uncertainty of temperature c (8t) = 8o A.6.6 Drift of reference standard (: Based on previous experience, the temperature change caused by the aging of the platinum resistance thermometer used as the reference standard should be within 0.4°C of the temperature setting of the dry body furnace temperature block, and the temperature display table of the temperature controller has a resolution of 0.1°C. The error caused by them is not measured in units of temperature. Note: If the temperature control is not calculated to obtain a relative temperature. A.6.8 Temperature between holes
± 0.05°C, and the temperature is evenly distributed. The error of |tt|| should be calculated by
using the relevant coefficient
(8R): The calibrator has 6 holes. At 180℃, the maximum temperature difference between the temperature measuring holes is 0.07℃. Range:
0.14℃, and the temperature distribution difference between the holes should be uniformly distributed.
A.6.9 Hysteresis effect
: The deviation of the temperature display in the temperature rise and fall measurement cycle
is estimated to be 0.5℃, uniformly distributed.
A6.10 Axial uniformity of temperature (8): The reading difference caused by the different depths caused by the axial temperature unevenness of the dry body furnace hole is estimated to be within ±
5℃, uniformly distributed
Load of uniform temperature block): The influence of the maximum load of the center hole is 0.05℃, uniformly distributed. A. 6.11 Temperature uncertainty (atv): The temperature is uniformly distributed within a temperature change of ±0.03°C. Correlation: The individual inputs in this measurement cycle are uncorrelated. The resolution limit of the temperature meter caused by the temperature stability within the min does not reflect the dispersion of the measured data. Repeatability of measurement: The uncertainty is summarized in Table ICHIN Estimated value NEMETROLOGY Standard uncertainty Sensitivity coefficient u(a)/°C Uncertainty component uCy/°C1. The temperature distribution of the dry-body furnace cannot be accurately known. Different loads and different stabilization times cause the temperature displayed on the temperature control table of the dry-body furnace to produce an additional temperature deviation from the measurement area. The area used by the customer may be different from the calibration area (measurement area). Therefore, this additional deviation cannot be corrected. The measurement uncertainty components can be estimated using the measurement results of 7.2.3 and 7.2.4. A3.2 The measurement uncertainty components at the calibration point can be obtained by linearizing the internal difference of the measured value. In the room temperature range, the uncertainty components can be set to fixed values. For example: calibrate the dry-body furnace, its temperature range is -30℃t200℃. The calibration ambient temperature is 20℃. At the calibration point 1 in the temperature zone, the maximum temperature difference is 0.3℃ when 1=-30℃: The maximum temperature difference is 0.6℃ when 1-200℃. In the temperature range of 20℃±50℃, that is, in the range of 30℃ to 70℃, the maximum temperature difference should be given as 0.3℃: In the temperature range of 70℃ to 200℃: It should correspond to linear internal differences of 0.3℃ and 0.6℃. A.4 Uncertainty due to the load effect of the dry block The measurement uncertainty component can be estimated using the measurement results of 7.2.5. A.5 Uncertainty of temperature deviation due to heat conduction When the outer diameter of the calibrated thermometer is d≤6mm, the measurement uncertainty component of the temperature deviation due to heat conduction can be ignored. If the outer diameter of the calibrated thermometer is 6mm, the measurement uncertainty should be analyzed separately. If the temperature deviation due to heat conduction of the calibrated thermometer can be ignored: When using this dry block to calibrate the measurement uncertainty of the thermometer according to the method specified in its operating manual and calibration certificate, the measurement uncertainty given in the dry block calibration certificate should be quoted.
A6 Example of measurement uncertainty calculation
The following is a calibration of a dry block with a built-in temperature display, set to 180℃. A.6.1 When the dry block furnace stably displays 180°C, a calibrated platinum resistance thermometer is used as a reference standard and inserted into one of the holes of the dry block furnace. The actual temperature is obtained by measuring the resistance using an AC bridge. A.6.2 When the built-in temperature display is 180°C, the temperature deviation in the hole is △/measured by the mathematical model A=t-t+ot+ap+o+ot+otu+at+ott+aty, where △ is the temperature indication deviation, is the dry block furnace display temperature, t is the temperature of the dry block furnace temperature measurement hole, and t, o,,,ov are the various deviations.
A.6.3 In the calibration: the outer diameter d6mmrm of the reference resistance thermometer used: the influence caused by the heat conduction of the thermometer rod is not considered. Previous studies have shown that the effect of heat conduction of the rod should be ignored under such measurement conditions. A6.4 Actual temperature (t): By checking the calibration certificate of the reference standard resistance thermometer, the measured temperature value is 180.10℃. The expanded uncertainty of the measurement is 0H03N (0.03N/ ... A.6.5 Influence of resistance measurement (o)
The error caused by the electrical measuring equipment is converted into the standard uncertainty of temperature c (8t) = 8o A.6.6 Drift of reference standard (: Based on previous experience, the temperature change caused by the aging of the platinum resistance thermometer used as the reference standard should be within 0.4°C of the temperature setting of the dry body furnace temperature block, and the temperature display table of the temperature controller has a resolution of 0.1°C. The error caused by them is not measured in units of temperature. Note: If the temperature control is not calculated to obtain a relative temperature. A.6.8 Temperature between holes
± 0.05°C, and the temperature is evenly distributed. The error of |tt|| should be calculated by
using the relevant coefficient
(8R): The calibrator has 6 holes. At 180℃, the maximum temperature difference between the temperature measuring holes is 0.07℃. Range:
0.14℃, and the temperature distribution difference between the holes should be uniformly distributed.
A.6.9 Hysteresis effect
: The deviation of the temperature display in the temperature rise and fall measurement cycle
is estimated to be 0.5℃, uniformly distributed.
A6.10 Axial uniformity of temperature (8): The reading difference caused by the different depths caused by the axial temperature unevenness of the dry body furnace hole is estimated to be within ±
5℃, uniformly distributed
Load of uniform temperature block): The influence of the maximum load of the center hole is 0.05℃, uniformly distributed. A. 6.11 Temperature uncertainty (atv): The temperature is uniformly distributed within a temperature change of ±0.03°C. Correlation: The individual inputs in this measurement cycle are uncorrelated. The resolution limit of the temperature meter caused by the temperature stability within the min does not reflect the dispersion of the measured data. Repeatability of measurement: The uncertainty is summarized in Table ICHIN Estimated value NEMETROLOGY Standard uncertainty Sensitivity coefficient u(a)/°C Uncertainty component uCy/°C7 Dry block temperature controller measurement resolution (8t dry block temperature setting gives a temperature resolution of 0.4 ° C, evenly distributed. The temperature display of the temperature controller is 0.1 ° C, the error caused by the error should be calculated by the relevant coefficient (8R): The calibrator has 6 holes. At 180 ° C, the temperature measuring hole The maximum temperature difference between the holes is 0.07℃ Range:
0.14℃, the temperature distribution difference between the holes should be uniformly distributed.
A.6.9 Hysteresis effect
: The deviation of the temperature display due to the hysteresis effect is estimated to be 0.5℃, uniformly distributed
A6.10 Axial uniformity of temperature (8): The reading difference caused by the axial temperature unevenness of the dry furnace hole is estimated to be within ±
5℃, uniformly distributed
Load of uniform temperature block): The maximum load effect of the center hole is 0.05℃, uniformly distributed. A.6.11 Temperature non-uniformity (atv): The temperature change is ±0.03℃,
uniformly distributed.
Correlation: In this
measurement cycle
the input quantities are uncorrelated
min due to the temperature stability
limitation of the resolution of the manual temperature meter, and the dispersion of the previous measurement data. Repeatability of measurement:
Understanding is summarized in the table ICHIN
Estimated value
NEMETROLOGY
Standard uncertainty
Sensitivity coefficient
u(a)/℃
Product partner network
Uncertainty component
uCy/℃7 Dry block temperature controller measurement resolution (8t dry block temperature setting gives a temperature resolution of 0.4 ° C, evenly distributed. The temperature display of the temperature controller is 0.1 ° C, the error caused by the error should be calculated by the relevant coefficient (8R): The calibrator has 6 holes. At 180 ° C, the temperature measuring hole The maximum temperature difference between the holes is 0.07℃ Range:
0.14℃, the temperature distribution difference between the holes should be uniformly distributed.
A.6.9 Hysteresis effect
: The deviation of the temperature display due to the hysteresis effect is estimated to be 0.5℃, uniformly distributed
A6.10 Axial uniformity of temperature (8): The reading difference caused by the axial temperature unevenness of the dry furnace hole is estimated to be within ±
5℃, uniformly distributed
Load of uniform temperature block): The maximum load effect of the center hole is 0.05℃, uniformly distributed. A.6.11 Temperature non-uniformity (atv): The temperature change is ±0.03℃,
uniformly distributed.
Correlation: In this
measurement cycle
the input quantities are uncorrelated
min due to the temperature stability
limitation of the resolution of the manual temperature meter, and the dispersion of the previous measurement data. Repeatability of measurement:
Understanding is summarized in the table ICHIN
Estimated value
NEMETROLOGY
Standard uncertainty
Sensitivity coefficient
u(a)/℃
Product partner network
Uncertainty component
uCy/℃
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