Some standard content:
National Metrology Verification Regulation of the People's Republic of China JJG128—2003
Standard Mercury -- in - Glass Thermometers (Grade I )2003-09-23 Issued
Implementation on 2004-03-23
Promulgated by the General Administration of Quality Supervision, Inspection and Quarantine JJG128—2003
Verification Regulation of Standard Mercury-in-Glass Thermometers(Grade I)JJG128—2003
Replaces JJG128—1989
This regulation was approved by the General Administration of Quality Supervision, Inspection and Quarantine on September 23, 2003, and came into effect on March 23, 2004.
Responsible unit:
Main drafting unit:
National Technical Committee on Temperature Metrology
Guizhou Institute of Metrology and Testing
Shanxi Institute of Metrology and Verification
Liaoning Institute of Metrology and Science
This regulation is entrusted to the National Technical Committee on Temperature Metrology to be responsible for the interpretation of this regulation. Main drafters:
Sun Tianxiang
Sun Yunfei
Participating drafters:
Liu Yingrong
Jin Wenjie
JJG128-2003||tt ||(Guizhou Metrology and Testing Institute)
(Shanxi Metrology Supervision and Verification Testing Institute) (Liaoning Metrology Science Research Institute)
(Guizhou Electric Power Testing and Research Institute)
(Shanxi Metrology Supervision and Verification Testing Institute) (Huzhou Shuanglin Xinli Instrument Factory)
(Yunnan Metrology and Testing Technology Research Institute) 1
Scope·
Metrology performance requirements
Indication error
Indication stability
3.3 Uniformity of capillary and scale division
4 General technical requirements||tt ||Glass·
Sensing liquid and liquid column
Scale and marking
Partial dimensions of thermometer·
5 Control of measuring instruments
Verification conditions
Verification items
Verification methods
Processing of verification results
Verification cycle
Appendix A
Appendix B
Appendix C
Appendix D
Appendix E
JJG128—2003
Extension of indication correction value of second-class standard mercury thermometer Uncertainty verification record format 1
Verification record format 2
Verification certificate of second-class standard mercury thermometer (inner page format) Verification result notice of second-class standard mercury thermometer (inner page format) (1)
(3)
(3)
.JJG128—-2003
Verification procedure for second-class standard mercury thermometer
This procedure applies to the initial verification, subsequent verification and in-use inspection of second-class standard mercury thermometers with a measurement range of (-60～+300)℃ and a graduation value of 0.1℃. 2 Overview
The second-class standard mercury thermometer (hereinafter referred to as the thermometer) measures temperature by using the principle of thermal expansion and contraction of mercury (mercury-based) in the temperature-sensing bulb and capillary. Its structure is divided into two types: rod type and internal standard type. It is mainly used as a standard for the verification of thermometers for work, and can also be used for precise temperature measurement. 3 Metrological performance requirements
3.1 Indication error
The indication error of the thermometer shall not exceed the provisions of Table 1, and its indication verification result shall be expressed by the indication correction value. The zero position of the thermometer with different measuring ranges (hereinafter referred to as zero position) shall not exceed the provisions of the indication allowable error limit of the corresponding temperature range in Table 1.
Table 1 Indication allowable error limit
Measuring range
3.2 Indication stability
Indication allowable error limit
First verification
Subsequent verification and in-use inspection
The indication stability of the thermometer is assessed by the zero position rise value and the low drop value, which shall comply with the provisions of Table 2. 3.3 Uniformity of capillary and scaled lines
The uniformity of capillary and scaled lines is assessed by the difference between the actual midpoint indication correction value and the interpolated midpoint indication correction value of two adjacent calibration points. The difference shall not exceed 0.08℃. Upper limit temperature
150, 200
250, 300
4 General technical requirements
4.1 Glass
JJG128—2003
Table 2 Indication stability
The zero rise value shall not exceed
The zero drop value shall not exceed
4.1.1 The thermometer glass shall be smooth and transparent, and there shall be no defects that affect the reading and strength within the scale range and on the temperature-sensing bulb.
4.1.2 The thermometer shall be straight, uniform in thickness, and shall not have obvious bending. 4.1.3 The cross section of the capillary glass should be circular. The capillary should be straight, the aperture must be uniform, and there should be no impurities in the tube. It should be filled with dry neutral gas of corresponding pressure. The connection between the capillary and the temperature-sensing bulb, the intermediate bulb, and the safety bulb should be smooth and arc-shaped, without necking phenomenon, and the top of the safety bulb should be sealed. 4.1.4 The rod thermometer should be melted into a white glaze band. The sleeve of the internal standard thermometer should be clean, free of impurities and dirt, and should be filled with dry gas, without haziness that affects the reading. 4.2 Temperature-sensing liquid and liquid column
4.2.1 Mercury or mercury-based alloy must be pure, dry, and free of bubbles, and the liquid column must not be broken. Mercury-based alloys must not solidify within the measurement range.
4.2.2 When the temperature-sensing liquid rises with temperature changes, there must be no obvious stagnation or jumping phenomenon; after falling, no liquid marks should be left on the tube wall.
4.3 Graduation and marking
4.3.1 The scale lines (hereinafter referred to as scale lines) on the scale should be perpendicular to the center line of the capillary. When observing the temperature from the front, all scale lines and temperature numbers of the rod thermometer should be projected within the glaze band. The capillary of the internal standard thermometer should be fastened to the center of the scale plate, and the displacement on the opposite side should not exceed the shortest scale line. The distance between the capillary and the scale plate should not be greater than 1mm.
4.3.2 The scale lines should be uniform, and the distance between two adjacent scale lines should not be less than 0.5mm. The width of the scale lines should not be greater than one tenth of the distance between two adjacent scale lines. There should be no less than 10 extended scale lines outside the upper and lower limits and the zero scale line. 4.3.3 Numbers and scale lines should be clear and complete, and the coloring should be firm and not fall off. The thermometer should be marked with numbers every 2℃. 4.3.4 Thermometers shall have the following markings: the symbol for the international temperature scale Celsius, the graduation value of the thermometer, the name or factory mark of the manufacturer, the year and month of manufacture, the factory number, and the mark and number of the manufacturing measuring instrument license. 4.4 Some dimensions of thermometers
4.4.1 The distance between the zero mark and the upper end of the temperature-sensitive bulb shall not be less than 40mm; 4.4.2 The distance between the lower limit temperature mark and the upper end of the intermediate bulb shall not be less than 50mm; 4.4.3 The distance between the upper limit temperature mark and the lower end of the safety bulb shall not be less than 30mm; 4.4.4 For thermometers with a lower limit temperature below 0℃, the distance between the lower limit temperature mark and the upper end of the temperature-sensitive bulb shall not be less than 2
JJG128—2003
4.4.5 The total length of the thermometer shall not exceed 540mm; the outer diameter of the rod thermometer is ($7±1) mm. 4.4.6 The outer diameter of the temperature-sensing bulb of a rod-type thermometer shall not be greater than the outer diameter of the glass rod, and the outer diameter of the temperature-sensing bulb of an internal standard thermometer shall not be greater than the outer diameter of the lower body casing.
5 Control of measuring instruments
Control of measuring instruments includes: initial verification, subsequent verification and in-use inspection. 5.1
Verification conditions
See Table 3 for standard instruments and supporting equipment.
Table 3 Standards and supporting equipment
Equipment name
Standard mercury thermometer
Standard platinum resistance thermometer
Precision temperature measuring bridge
Photoelectric amplification galvanometer
Special four-point conversion switch
Constant temperature bath
Water triple point bottle
Reading telescope
Magnifying glass
Ice point device
Ice making and crushing device
Note: *
Technical requirements
Relative error after quoting correction value≤1×10-matched with bridge
Horizontal temperature difference in working area≤0.015℃
Temperature difference at any depth in working area≤0.03℃Temperature fluctuation does not exceed±0.02℃/10minMagnification: 5 times or more
Magnification: 3 times or more
Other electrical measuring equipment with technical indicators not lower than the requirements can also be used. Other constant temperature devices with technical indicators that meet the requirements can also be used. Other reading systems with technical indicators that meet the requirements can also be used. Second-class standard platinum resistance thermometers are used as standard instruments during arbitration verification. 5.1.2 Environmental conditions should meet the requirements of the corresponding equipment. 5.2 Verification items
Thermometer verification items are shown in Table 4.
5.3 Verification methods
5.3.1 General technical requirements Inspection
5.3.1.1 Mainly use visual inspection method, and corresponding length measuring tools can be used when necessary. Standard instrument
Standard instrument
Equipped with second-class standard platinum resistance temperature
Equipped with bridgeWww.bzxZ.net
Connected with standard platinum resistance thermometer
Constant temperature device for calibration
Measure the triple point value of thermometer water
Read the indication of mercury thermometer
Inspect the appearance
Zero position calibration
Ice making and ice crushing
Calibration items|| General technical requirements Indication error Indication stability Capillary uniformity and scale division uniformity JJG128-2003 Verification items Initial verification Subsequent verification Note: "+" in the table indicates items to be inspected, and "_" indicates items that may not be inspected. ℃ Inspection in use 5.3.1.2 Inspection of the temperature-sensing liquid of mercury-based thermometers Spot checks can be carried out on thermometers for the first verification, and the method is as follows. After the thermometer is inserted into a thermostatic bath at -60℃±0.1℃ for 2 hours, observe the indication of the thermometer; readjust the temperature of the thermostatic bath to 0.2℃ lower than the above temperature, keep it constant for 30 minutes, tap the thermometer, and then observe whether the indication of the thermometer changes accordingly. The liquid column shall not shrink into the temperature-sensitive bulb or solidify in the capillary. 5.3.2 Verification of indication stability
5.3.2.1 Insert the thermometer at the upper temperature limit, immerse it to the lower temperature limit scale of the thermometer for 30 minutes, remove it and cool it, and measure the zero position.
5.3.2.2 Insert the thermometer at the upper temperature limit, immerse it to the lower temperature limit scale of the thermometer for 24 hours, remove it and cool it, and measure the zero position.
5.3.2.3 Insert the thermometer at the upper temperature limit and immerse it to the lower temperature limit scale of the thermometer for 10 minutes. Turn off the heating power of the thermostat. When the mercury level of the thermometer drops to about 2°C above the lower temperature limit scale, insert it downward and immerse it at the upper temperature scale. Allow it to slowly cool to near room temperature with the medium, then take it out to measure the zero position. 5.3.2.4 The zero position measured in 5.3.2.2 minus the zero position measured in 5.3.2.1 is the zero position rise value. The zero position measured in 5.3.2.2 minus the zero position measured in 5.3.2.3 is the zero position drop value. 5.3.3 Verification of indication error
5.3.3.1 The zero position can be verified by comparison method or fixed point method. The comparison method is used for other temperature points. 5.3.3.2 Take 0℃ as the boundary, and calibrate at intervals of 10℃ in the upper or lower limit direction. 5.3.3.3 The indications of the first-class standard mercury thermometer and the thermometer to be tested are read with a reading telescope, and its level must be adjusted before reading. When reading, read the indication deviation from the nominal temperature of the calibration point, and estimate the reading to one-tenth of the scale value. 5.3.3.4 When using a first-class standard mercury thermometer as a standard, the thermometer should be vertically inserted into the constant temperature bath in the specified immersion method, and the height of the liquid column exposed on the cover of the constant temperature (or freezing point) bath should be consistent and shall not exceed 10 scale values. 5.3.3.5 When using a second-class standard platinum resistance thermometer as a standard, the insertion depth of the platinum resistance thermometer should be not less than 250mm, and the current passing through the platinum resistance thermometer is 1mA. The thermometer to be tested should be vertically inserted into the constant temperature bath in accordance with the provisions of Article 5.3.3.4.
5.3.3.6 When calibrating a higher temperature, the thermometer must be preheated before insertion, and the reading can be taken only after the bath temperature stabilizes. When starting to read, the bath temperature should not deviate from the calibration point temperature by more than ±0.2°C (based on the standard). During the reading process, the bath temperature must be constant or change slowly and evenly, and the readings must be rapid and the time intervals must be uniform. After reading a calibration point, the bath temperature change must not exceed 0.04°C.
5.3.3.7 Reading starts from the standard, reads to the object to be tested, and then reads from the object to be tested to the standard as one cycle, and a total of four round trips are two cycles. When using a first-class standard mercury thermometer as a standard, the standard should be rotated 180° in the second cycle. After the reading is completed, another calibrator should check for errors. 5.3.3.8 The zero position of the thermometer to be tested should be measured after the lower and upper temperature limits are calibrated, which are called the lower limit zero position and the upper limit zero position respectively. The zero position of the standard instrument must be calibrated in the triple point of water, and the zero position of the thermometer to be tested can also be calibrated in an ice point device or a constant temperature bath. The requirements for zero position determination are shown in Table 5. Table 5 Zero position determination
Temperature range
250~300
Second-class standard platinum resistance thermometer
Standard
First-class standard mercury thermometer
Determine zero position before calibration
Determine zero position after lower and upper limit calibration, and often measure the resistance value of standard platinum resistance thermometer at water triple point temperature
The zero position of each calibration point is calculated by linear interpolation
The zero position of the first, third, fifth and sixth points is determined after calibration, and the zero position of the second and fourth points is calculated by linear interpolation
Note: The arbitration calibration is carried out in the water triple point bottle using the fixed-point method. 5.3.4 Capillary and scale division uniformity test The first test point of the thermometer to be tested is zero position The zero position is not measured after the lower limit test The zero position is measured after the lower and upper limits are tested The thermometer to be tested for the first time should be checked for the uniformity of its capillary and scale divisions. The midpoint value between two adjacent test points should meet the requirements of Table 1. At the same time, the calculated uniformity of the capillary and scale divisions should meet the requirements of 3.3. 5.3.5 Calculation of test results 5.3.5.1 Use a second-class standard platinum resistance thermometer as a standard a) The temperature measured by the standard can be calculated by table interpolation. The actual temperature deviation △t in the tank determined by the standard instrument is calculated according to formula (1):
At=tt,
W——the actual tank temperature, ℃;
t.——the nominal temperature for calibration, ℃;
W——the resistance ratio R./Rp at the temperature!
——the temperature given by the graduation table, the corresponding resistance ratio and the resistance ratio change rate. b) The correction value of the value to be tested*2 is calculated according to formula (2): (1)
JJG128—2003
x2=t-AA2
W——the average value of the deviation of the reading of the thermometer to be tested, ℃. 5.3.5.2 Use a first-class standard mercury thermometer as a standard instrument a) The zero position a of the standard thermometer measured at the triple point of water is calculated according to formula (3): a
Where: a——the front reading of the standard thermometer with respect to the 0℃ scale line deviation, grid; a\——the back reading of the standard thermometer with respect to the 0℃ scale line deviation, grid; d, —the scale value of the standard thermometer, ℃/grid. b) The zero position az of the thermometer under test measured at the triple point of water is calculated according to formula (4): a2=a2×dz-0.01
Where: a2——the reading of the thermometer under test with respect to the 0℃ scale line deviation, grid; dz——the scale value of the thermometer under test, ℃/grid. c) The zero position a of the thermometer under test measured in the freezing point device or the alcohol low temperature tank is calculated according to formula (5): as = a2 - ar + ai
wherein: a, is the indication deviation of the thermometer under test read in the freezing point device or the low temperature tank, grid; a, is the indication deviation of the standard thermometer read in the freezing point device or the low temperature tank, grid; ai - has the same meaning as formula (3).
d) The actual temperature deviation △1 in the tank determined by the standard instrument is calculated according to formula (6): At=AA,+xa
wherein: AA, is the average value of the standard instrument reading, ℃; x
is the graduation correction value corresponding to the nominal temperature of the calibration point given on the calibration certificate of the standard instrument, ℃; ai - has the same meaning as formula (3) or is calculated by linear interpolation to obtain the zero position of the standard instrument, ℃. e) The corrected value xz of the detected value is calculated according to formula (7): x2 =△t -AA2
where: △A, has the same meaning as formula (2). 5.4 Processing of the test results
5.4.1 In subsequent calibration, the difference between the indication correction value of the current calibration and the previous calibration result (the change in zero position must be deducted, that is, the comparison is made under the same zero position) shall not exceed the provisions of Table 6. If any point exceeds the provisions, a re-inspection shall be carried out to find out the reason and confirm the validity of this cycle calibration before the calibration certificate can be filled out; otherwise, a calibration result notice shall be issued.
5.4.2 A calibration certificate shall be issued for thermometers that have passed the calibration in accordance with the requirements of this regulation. The indication correction value and the upper and lower zero limits given on the certificate shall be revised to approximately one-tenth of the scale value. If the calibration fails, a calibration result notice shall be issued, and the unqualified items shall be pointed out.
5.5 Calibration cycle
The calibration cycle of a thermometer generally does not exceed 2 years. 6
Temperature range
-60~-10
100~200
200~300
JJG128—2003
Table 6 Difference of indication correction values between two periodic calibrations℃
The absolute value of the difference of indication correction values between two periodic calibrations (excluding the change of zero position) shall not exceed
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