Some standard content:
National Metrology Verification Regulation of the People's Republic of China JJG160-2007
Standard Platinum Resistance Thermometer
Standard Platinum Resistance Thermometer2007-06-14Published
2007-12-14Implemented
The General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China issued JJG160-2007
Standard Platinum Resistance Thermometer
Verification Regulation of
Standard Platinum Resistance Thermometer ThermometerJJG1602007
Replaces JJG160—1992
JJG716—1991
JJG859—1994
This regulation was approved by the General Administration of Quality Supervision, Inspection and Quarantine on June 14, 2007 and came into effect on December 14, 2007.
Responsible unit: National Technical Committee on Temperature Metrology Drafting unit: China Institute of Metrology Fluke Corporation of the United States
Beijing Conster Technology Development Co., Ltd. Kunming Dafang Automatic Control Technology Co., Ltd. Beijing Guodian Diyang Electric Equipment Co., Ltd. This regulation is interpreted by the National Technical Committee on Temperature Metrology Drafting person of this regulation:
JJG160--2007
Product Service Electric Static and Dynamic
Wang Yulan (China Institute of Metrology) Wu Helian (China Institute of Metrology) Qiu Ping (China Institute of Metrology)
Zhang Zhe (China Institute of Metrology)
Feng Yuling (China Institute of Metrology) Scope·
2 Overview…·
2.1 Definition and interpolation method of temperature value
2.2 Explanation of symbols
3 Metrological performance requirements
3.1 Resistance characteristics·
3.2 Technical conditions.
4 General technical requirements
4.1 Appearance dimensions.
Structure·
5 Control of measuring instruments
5.1 Verification conditions·.
Verification items
Verification methods
Calculation formula·
Processing of verification results·
5.6 Verification cycle
Appendix A
Appendix B
Appendix C
Appendix D
Appendix E
Appendix F
Verification certificate (back) format
JJG160—2007
Verification result certificate Instruction (back) format
Numerical table of coefficients of reference function W(t)
Numerical table of coefficient K in the formula for calculating W(100℃) (-189.34420.01)℃ reference function table (0～660.323)℃ reference function table (1)
(4)
1 Range
JJG160-—2007
Verification procedures for standard platinum resistance thermometers
This procedure applies to the initial and subsequent verification of working reference, first-class and second-class standard platinum resistance thermometers with a temperature range of -189.3442℃~660.323℃ (or each sub-temperature range). 2 Overview
Standard platinum resistance thermometer is a standard instrument for measuring temperature based on the characteristic that the resistance of a metal platinum wire changes with temperature.
The purpose of standard platinum resistance thermometer is: national standard platinum resistance thermometer is the standard of working standard platinum resistance thermometer calibration device: working standard platinum resistance thermometer is the standard of first-class standard platinum resistance thermometer calibration device: standard platinum resistance thermometer is the standard of second-class standard platinum resistance thermometer calibration device: standard platinum resistance thermometer can be used directly for measurement, and can also be used as a standard for various comparative measurements. 2.1 Definition and interpolation method of temperature value
The 1990 International Temperature Scale (ITS90) stipulates that the temperature value in the temperature range of -189.3442℃～660.323℃ is determined by standard platinum resistance thermometers graduated at a set of defined fixed points, including aluminum solidification point, zinc solidification point, tin solidification point, steel solidification point, gallium melting point, mercury triple point, argon triple point and water triple point device, and uses the specified reference function and deviation function to interpolate and calculate the temperature value between the defined fixed points. The temperature value is determined by the following formula:
W()=R(t)/R(0.01C)
W(t) is the ratio of the resistance value of the standard platinum resistance thermometer at temperature t to the resistance value at the triple point temperature of water (0.01°C).
The reference function in the temperature range of 0°C to 660.323°C is defined as W.(t)=C,+
CC[(/C-481)/481]
Formula (3) is the inverse function of formula (2), which is consistent with formula (2) within 0.13mK: t/°C=D. +D,([W(t)-2.64]/1.64](2)
wherein, t is the temperature value; W() is the reference function. The numerical table of the reference function W.(t) in the temperature range of 0℃～660.323℃ is shown in Appendix F; constants Cn, C., Do, D, are listed in Appendix C. The deviation function in the temperature range of 0℃～660.323℃ is △W(t) = W() - W(t) = a[W(t) -1] + b[W(t) -1)2 + c[W() - 173(4)wherein, a, b, c are coefficients. The coefficients a, 6, c are obtained by the deviation between the W value obtained by measuring the water triple point, tin solidification point, zinc solidification point and aluminum solidification point with a standard platinum resistance thermometer and the corresponding reference function. JJG160—2007
In the temperature range of 83.8058K~273.16K-189.3442℃~0.01℃), the reference function is InlW(T)l=A+
A[In(Too/273.16K)+1.5]/1.5]
Equation (6) is the inverse function of equation (5), which is consistent with equation (5) within 0.13mK: B.[W.(To)o -0.65)
Too/273.16K=B+
In the temperature range of 83.8058K~273.16K (-189.3442℃~0.01C), the deviation function is (5)
AW(t) = W(T) - W.(T) = a[W(T) -1) + 6[W(T) -1JInW(I)(7)
In the formula, the coefficients α and b are obtained from the measured values of the thermometer at the triple point of water, the triple point of argon and the triple point of mercury. The deviation function in the temperature range of -200℃ to 0℃ is Appendix E, and the coefficient table of the reference function is shown in Appendix C. 2.2 Explanation of symbols
R, is the resistance value of the standard platinum resistance thermometer at the triple point of water (0.01℃); W is the ratio of the resistance value RA of the standard platinum resistance thermometer at the solidification point of aluminum (660.323℃) to R,; W is the ratio of the resistance value Rz of the standard platinum resistance thermometer at the solidification point of zinc (419.527℃) to R,; Ws is the ratio of the resistance value Rs of the standard platinum resistance thermometer at the solidification point of tin (231.928℃) to R ; W. is the ratio of the resistance value R. of the standard platinum resistance thermometer at the freezing point of steel (156.5985℃) to R,; W is the ratio of the resistance value RG of the standard platinum resistance thermometer at the melting point of iron (29.7646℃) to R; W is the ratio of the resistance value R of the standard platinum resistance thermometer at the triple point of mercury (-38.8344℃) to R,; W, is the ratio of the resistance value R of the standard platinum resistance thermometer at the triple point of argon (-189.3442℃) to R,. 3. Metrological performance requirements
Standard platinum resistance thermometer (hereinafter referred to as thermometer). 3.1 Resistance characteristics
The nominal resistance value R of the thermometer at the triple point temperature of water (0.01℃) shall be 25Q or 1002, and R shall meet the requirements of 25Q±12 and 1002±22 respectively. Thermometers with other nominal values may refer to this. 3.2 Technical conditions
3.2.1 Temperature sensing element
The temperature sensing element of the thermometer must meet one of the following two conditions: Wc ≥ 1.11807
W ≤ 0.844235
3.2.2 Stability
3.2.2.1 The thermometer to be calibrated for the first time should be annealed at the upper limit temperature required in different temperature zones. Generally, the thermometer used above 600℃ is annealed at 660℃ for 4h, while the thermometer used below 600℃ is annealed at 600℃ for 4h, and then R. and R, at the upper limit fixed point are measured, and then W is calculated. Then, after annealing at 660℃ or 600℃ for 100h, R, and W are measured again. The absolute value of the difference between the measured values before and after annealing converted into a temperature difference should not exceed the value specified in Table 1. Stability 2
After the assessment, the temperature zone calibration is carried out. JJG160—2007
Stability requirements for thermometers to be calibrated for the first time
Working benchmark
Stability requirements for thermometers to be calibrated for the first time
First-class standard
SOHONT
Second-class standard
Stability requirements for thermometers at each fixed point and the results of adjacent periodic calibration. mk
After annealing at the required upper temperature limit for 2 hours, the absolute value of the difference between the fixed points of the thermometers with different use ranges and different structures should not exceed the R
value specified in Table 2. During the calibration process, the absolute value specified in Table 2 should not exceed the R
value specified in Table 2.
Absolute value of the maximum difference:
maximum
Stability requirements for the thermometer in use
The difference between multiple non-reference values at each fixed point converted into temperature values should not exceed the difference in table
The value of the calibration result of two adjacent cycles
working reference
The value of the calibration result of the thermometer at each fixed point and the previous cycle should not exceed the absolute value of the difference converted into temperature specified in table 2.
METROLOGY
3.2.3 Thermoelectric properties
3.2.3.1 Self-heating effect: The self-heating effect measured at the triple point temperature of water converted into a temperature value should not exceed the provisions of table 3. Table 3
Self-heating effect/mK
Thermoelectric potential/μV
Working standardbzxZ.net
Self-heating effect and thermoelectric potential
First-class standard
Second-class standard
3.2.3.2 Thermoelectric potential: The thermoelectric potential between any two leads of the thermometer should not exceed the provisions of Table 3 when the thermometer is at the upper freezing point.
JJG160—2007
3.2.3.3 Insulation resistance: The resistance between the metal shell of the handle and the lead of the thermometer at ambient temperature should not be less than 200M0.
4 General technical requirements
4.1 Appearance size
4.1.1 The thermometer should be marked with the manufacturer's nameplate and factory number. The supporting frame of the thermometer and its temperature sensing element should be complete and free of cracks, there should be no debris in the protective tube, and the components should be firmly fixed. 4.1.2 The length of the outer protective tube of the thermometer used above 600℃ is 510mm±10mm, and the length of the outer protective tube of the thermometer used below 600℃ is 470mm±10mm. The outer diameter is less than 6mm~7.5mm. The outer wall of the tube needs to be treated to suppress heat radiation. The temperature sensing element should be located within 60mm from the top of the protective tube (the diameter and length are allowed to change for special temperature requirements). 4.1.3 The thermometer jacket should be clean, free of oil or other attachments. 4.2 Structure
4.2.1 The temperature sensing element of the thermometer should adopt a stress-free structure. The platinum wire of the temperature sensing element should be able to expand and contract freely when the temperature changes.
4.2.2 The thermometer is a four-terminal resistor, that is, two leads are drawn from each end of the temperature sensing element, and the ends of the outer leads should be welded with copper terminals.
4.2.3 The outer protective tube of the thermometer should be sealed, and the tube should be filled with dry air containing oxygen. The outer protective tube shall not be damaged, scratched or crystallized.
5 Measuring instrument control
Measuring instrument control includes the initial calibration and subsequent calibration of the thermometer. 5.1 Calibration conditions
5.1.1 Environmental conditions
Ambient temperature (20±5)℃, relative humidity 15%～80%. There should be a cooling water channel and a shielded ground wire with a grounding resistance of less than 0.5Q in the room. 5.1.2 Measuring standards
The standard device for calibrating the working reference platinum resistance thermometer is the temperature reference device. The reference device includes a defined fixed point device and a national reference platinum resistance thermometer.
The standard device for calibrating the first-class standard platinum resistance thermometer is the working reference device. The working reference device includes a defined fixed point device, a liquid comparison tank and a working reference thermometer. The standard device for calibrating the second-class standard platinum resistance thermometer is the first-class standard device. The first-class standard device includes a defined fixed point device, a liquid comparison tank and a first-class standard thermometer. 5.1.3 Verification equipment
5.1.3.1 Fixed point device
The fixed point devices include aluminum, zinc, tin, and indium solidification point devices, melting point devices, mercury, argon, and water triple point devices, a total of eight.
Comparison verification device
JJG160—2007
Comparison verification devices include water boiling point and liquid nitrogen comparison devices. 5.1.4 Supporting equipment
5.1.4.1 Resistance measuring instrument. The electrical measuring equipment for measuring thermometers is a temperature measuring bridge. The temperature measuring bridge for the verification of the working benchmark requires that the relative error of the measured resistance value after the reference correction value is not greater than 8×10-7, and the relative error requirement of the temperature measuring bridge for the verification of the first-class standard is not greater than 2×10-. The relative error requirement of the temperature measuring bridge for the verification of the second-class standard is not greater than 1×10-5. If a standard resistor is required, the ambient temperature of the standard resistor should meet the accuracy requirements. Other electrical measuring equipment with technical indicators not lower than this requirement is allowed to be used. 5.1.4.2 Annealing furnace device. The use range of the annealing furnace is 200℃～700℃. When the furnace temperature is stable, the deviation and fluctuation from the nominal set point should be within 10℃. Within 60mm of the temperature sensing element, the maximum temperature difference of the vertical temperature field should not exceed 1℃.
5.1.4.3 The stray thermal potential of the four-terminal switch should not be greater than 0.4mV. 5.1.4.4 Low-potential DC potentiometer or digital voltmeter capable of measuring 0.1uV 5.1.4.5500V insulation resistance meter
5.2 Verification items
Verification items are shown in Table 4.
Table 4 List of verification items
Verification items
Appearance inspection
First verification stability
Annealing before verification
Wsr, w(100)
WA (liquid nitrogen comparison method)
Self-heating effect
Thermoelectric potential
Insulation resistance
First verification
Subsequent verification
Note: 1 "+" indicates an item to be inspected; "_" indicates an item that may not be inspected. 2 If the thermometer has no adjacent cycle data, it shall be calibrated according to the requirements for the first verification. 5.3 Verification method
5.3.1 Appearance inspection
Inspect the appearance of the thermometer, which shall comply with the provisions of 4.1 and 4.2 of this regulation. Remarks
1. Select a fixed point for calibration according to the temperature range to be inspected
2. Second-class standard thermometers are allowed to use water boiling point
3. First- and second-class standard thermometers are allowed to use nitrogen boiling point comparison method instead of argon triple point
5.3.2 Working current
The working current of the thermometer is 1mA.
5.3.3 Insulation resistance measurement
JJG160—2007
When the ambient temperature is between 15℃ and 30℃ and the relative humidity should not exceed 80%, use a megohmmeter to measure the resistance between the metal shell of the thermometer handle and the lead wire. The value should not be less than 200Ω5.3.4 Cleaning of the thermometer
For thermometers that have passed the appearance inspection, use anhydrous ethanol to clean the thermometer protection tube before annealing and aluminum solidification point verification. The cleaned thermometer should not be touched by hand or other objects on the surface of its protection tube to prevent product precipitation at high temperature.
5.3.5 Stability check of the thermometer for the first calibration The thermometer must be checked for stability for the first calibration. After annealing at 660℃ or 600℃ for 4h, the temperature drops to below 420℃ as the furnace temperature drops to below 420℃. Take out the thermometer and measure R. If the value specified in Table 1 is exceeded, it must be re-annealed at 660℃ or 600℃ for 100h. After annealing at 660℃ or 600℃ for 100h, anneal at 600℃ for 100h. The maximum difference of the thermometer converted into temperature should not exceed the value specified in Table 1. During the annealing process and measurement of R, the total annealing time should not exceed W. The absolute value of the difference between the two measured W should not exceed 350h. After Rm is qualified, the value specified in Table 1 shall be met. 5.3.6 Subsequent verification: For thermometers used between 600℃ and 400℃, annealing in different situations is required for fixed-point graduation. Thermometers should be annealed at 660℃ according to different upper limits of use and different structures, and annealed at the upper limit for 2h. For example, if used at 40018, annealing is required at 6000℃ and 450℃. Those used below temperature do not need to be annealed. In addition, different protective tubes are tested according to different temperature conditions. The subsequent test temperature sequence is to first anneal at 660 or 600C for 4h, and then test from high temperature to low temperature according to different temperature zones, according to R, RAR
Reay Rp, Rh Rp
Rp. Each thermometer should measure the triple point of argon twice at different temperatures. 5.3.8 The thermometer should be divided into two parts at different temperatures. The thermometer should be divided into two parts at different temperatures. The thermometer should be divided into two parts at different temperatures. The thermometer should be divided into two parts at different temperatures. The thermometer should be divided into two parts at different temperatures. The thermometer should be divided into two parts at different temperatures. The thermometer should be divided into two parts at different temperatures. The thermometer should be divided into two parts at different temperatures. The thermometer should be divided into two parts at different temperatures. The thermometer should be divided into two parts at different temperatures. The thermometer should be divided into two parts at different temperatures. The thermometer should be divided into two parts at different temperatures. The thermometer should be divided into two parts at different temperatures. The thermometer should be divided into two parts at different temperatures. The thermometer should be divided into two parts at different temperatures. 5.3.9 Measurement of self-heating effect
For the temperature measuring bridge with ×~/2 gear of the working current regulating switch, first measure the resistance value of the thermometer when the working current is 1mA, and then measure the resistance value when the working current is /2 times. The difference between the latter and the former is △R. The self-heating effect caused by the working current can be obtained by calculation according to formula (10), which should not exceed the requirements of Table 3. At=(R/R)/ldW(t)/dt)
In the formula, dW(t)/dt is the rate of change of the W value relative to the temperature at temperature t. To simplify the calculation, the dW(t))/dt of the reference function 6
JJG160-2007
can be used instead. The self-heating effect of the triple point of water can also be directly estimated by △R. Other methods can be used to measure the self-heating effect. 5.3.10 Thermoelectric potential measurement
Measure the thermoelectric potential of the thermometer at the aluminum solidification point or zinc solidification point according to the upper limit of the thermometer. When the thermometer reaches thermal equilibrium, use a DC potentiometer that can measure 0.1V low potential or a digital voltmeter with a resolution of no more than 0.2mV to directly measure the stray thermoelectric potential between any two leads. Its value should not exceed the requirements of Table 3. 5.3.11 Measurement of fixed points
The thermometer is graduated at each fixed point, and the requirements for thermometers of different grades are different. The working reference thermometer requires the self-heating effect to be measured at each fixed point, while the first and second grade standard thermometers only measure the self-heating effect at the water triple point, and do not need to measure at other fixed points. This correction is not made in the calculation. In addition, when calculating W after measuring the aluminum solidification point, the R of each grade of thermometer is required to be the average value of the R before and after measuring R.
The working reference platinum resistance thermometer uses the R before and after the fixed point to calculate the W value. Below 420℃, the first and second grade thermometers at each fixed point only use R after the fixed point to calculate the W value. 5.3.12 Measurement of WA
The following method can be used to measure W: After the metal in the fixed point container melts, control the furnace temperature within the range of 1.5℃ to 3℃ higher than the solidification point. Observe the temperature change of the monitoring platinum resistance thermometer in the fixed point container. If the temperature fluctuation is less than 0.1℃ within 10min, the temperature can be reduced at a rate of 0.10℃/min~0.15℃/min. When the value of the monitoring platinum resistance thermometer stops decreasing and starts to rise again, immediately remove the thermometer, insert a quartz tube at room temperature that has been cleaned with anhydrous ethanol and induced for 1min, then remove it. Then insert the cleaned thermometer to be divided into the fixed point furnace, and at the same time control the temperature of the solidification point furnace at a temperature about 1C lower than the solidification point. After the thermometer reaches thermal equilibrium, start reading. The working reference thermometer first reads the value at the specified measuring current, then measures the self-heating effect, and then reads the value of the thermometer at the specified measuring current. The difference between the previous and subsequent readings should not be greater than 0.4mK. The average value R is taken after correction (see 5.3.22 for the correction item and correction method) as the resistance value RA1 of the thermometer at the aluminum solidification point. The difference between several readings measured by first- and second-class standard platinum resistance thermometers should not be greater than 0.6mK. Two to three thermometers can be graduated at one temperature level, but the second and third graduated thermometers must be preheated at 650℃ before being inserted into the aluminum solidification point furnace. The thermometer after graduation should be immediately inserted into a 650℃ annealing furnace for 1.5h annealing treatment. The annealed thermometer can be taken out only when the furnace temperature drops below 420℃ in the annealing furnace. After the R measurement is completed and the thermometer is annealed, the R value should be measured according to the method in 5.3.8. WA is calculated by formula (11):
WA =RA/ Rtpl
Wherein: Rp is the average value of R before and after measuring RA. (11)
The absolute value of the difference between two W values obtained from different temperature levels should not exceed the value specified in Table 2 when converted into a temperature value. The average value is taken as the final calibration result. 5.3.13 Measurement of Wzm and W
The following method can be used to measure W and W: When the metal sample in the fixed point container is completely melted, the temperature of the fixed point furnace is controlled and maintained within the range of 1.5℃ to 3℃ higher than the solidification point. Insert a platinum resistance thermometer for monitoring into the fixed point container to observe its temperature change. If the temperature fluctuation is less than 0.1C within 10 minutes, the temperature can be reduced at a rate of 0.10℃/min to 0.15℃/min. When the temperature value of the monitoring platinum resistance thermometer stops decreasing and starts to rise, immediately remove the monitoring thermometer, insert a quartz tube at room temperature for induction for 1 minute, and then remove it. Then, clean the thermometer to be divided with anhydrous ethanol and insert it into the solidification point furnace. At the same time, control and maintain the temperature of the fixed point furnace at a temperature about 1℃ lower than the solidification point. After the thermometer reaches thermal equilibrium, start reading. The working reference thermometer first reads the value of the specified current, then measures the self-heating effect, and then reads the value of the specified current through the thermometer. The difference between the previous and next readings converted into a temperature value should not be greater than 0.3mK. Then take the average value RzmR after correction (correction items and correction methods are shown in 5.3.22) as the resistance values Rzm and Rm at the zinc solidification point and steel solidification point. The difference between several readings measured by first- and second-class standard platinum resistance thermometers should not be greater than 0.5mK. After the measurement of Rzm, R., R should be determined immediately according to the method in Article 5.3.8. Wzm and Wm are calculated by formula (12) and formula (13) respectively: Wzn=Rzn/Rp2
W=Rin/Rm
W, Rm——the average value of R and R before and after measuring Rz and R. (12)
The absolute value of the difference between two Wzn and W. obtained from different temperature levels should not exceed the value specified in Table 2 when converted into a temperature value. The average value is taken as the final calibration result. 5.3.14 Measurement of Wsn
The following method is used to measure W: When the metal tin in the fixed-point container is completely melted, the temperature of the fixed-point furnace is controlled and maintained within a range of 1.5℃ to 3℃ higher than the solidification point. A monitoring platinum resistance thermometer is inserted into the fixed-point container to observe its temperature changes. If the temperature fluctuation is less than 0.1℃ within 10 minutes, the molten tin can be cooled at a rate of 0.10℃/min0.15C/min. When the value of the monitored thermometer is lower than the solidification point of tin, the thermometer can be removed and a stainless steel rod can be inserted into the container and kept for 1.Take it out after 5-2 minutes, and connect the vent pipe of the container's heat-equalizing block at the same time, blow in indifference gas or dry air (compressed air) to cool the tin quickly. After taking out the stainless steel rod, insert the platinum resistance thermometer for monitoring. If its resistance value has risen to a value close to the temperature plateau value, take out the thermometer, insert the thermometer to be divided into the tin solidification point furnace, and quickly control and maintain the temperature of the fixed point furnace at a temperature about 1C lower than the solidification point. After the thermometer reaches thermal equilibrium, start reading. The working reference thermometer first reads the value at the specified measuring current, then measures the self-heating effect, and then reads the value of the thermometer at the specified measuring current. The difference between the previous and next readings should not be greater than 0.3mK. Then take the average value Rs after correction (see 5.3.22 for correction items and correction methods) as the resistance value Rsn of the thermometer at the solidification point of tin. The difference between several readings measured by first- and second-class standard platinum resistance thermometers should not be greater than 0.4mK.
After the measurement of Rsm is completed, Rm should be determined immediately according to the method in Article 5.3.8, and Ws should be calculated by formula (14): Wsn=Rsn/Rpt
Wherein: R is the average value of R measured twice before and after Rs is measured. (14)
The absolute value of the difference between two W values obtained from different temperature levels converted into a temperature value should not exceed the value specified in Table 2. The average value is taken as the final calibration result of Ws. 5.3.15 The difference between the holes of the metal boiling point device measuring 100°C (limited to the calibration of second-class standard thermometers) should not be greater than 1mK. After the metal water boiling point furnace reaches a stable boiling state, the thermometer to be tested and the standard thermometer are respectively inserted into the water boiling point furnace (in order to improve the heat exchange conditions, 8
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