This standard specifies the verification items and technical requirements of thermostatic water baths, verification instruments, verification methods, verification results and treatment. This standard applies to the verification of the working area of ​​thermostatic water baths for wires and cables. JB/T 4278.7-1993 Verification methods for rubber and plastic wire and cable test equipment Constant temperature water bath JB/T4278.7-1993 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
JB/T4278.7-1993
Verification Method of Rubber and Plastic Wire and Cable Testing Instruments and Equipment Constant Temperature Water Bath
Published on August 21, 1993
Ministry of Machinery Industry of the People's Republic of China
Implementation on October 1, 1993
Mechanical Industry Standard of the People's Republic of China
Verification Method of Rubber and Plastic Wire and Cable Testing Instruments and Equipment Constant Temperature Water Bath
1 Subject Content and Scope of Application
JB/T 4278.71993
Replaces JB4278.7-1986
The standard specifies the verification items and technical requirements, verification instruments, verification methods, verification results and processing of constant temperature water baths. This standard applies to the calibration of the working area of ​​the constant temperature water tank for wires and cables. 2 Reference standards
JB/T4278.1 General principles for the calibration of rubber and plastic wire and cable test instruments and equipment 3 Calibration items and technical requirements
The temperature deviation of the working area where the constant temperature water tank is placed shall comply with the provisions on temperature deviation in the relevant wire and cable test method standards. 4 Calibration instruments
4.1 Thermocouple wire diameter is 0.5mm, and the node diameter is not more than 2.0mm. Nickel-chromium-copper-nickel (constantan), nickel-chromium-nickel-silicon or other material thermocouples.
4.2 DC digital voltmeter
The actual measurement deviation is less than 0.05%. When using nickel-chromium-copper-nickel (constantan) thermocouples, the resolution of the digital voltmeter shall not be less than 10μV; when using other thermocouples, the resolution of the digital voltmeter shall not be less than 1V. 4.3 Thermocouple conversion switch
4.4 Second-class standard mercury thermometer.
4.5 Stopwatch graduation value 0.1s
4.6 Ice bottle.
5 Verification method
5.1 The working area is called the measured area during the verification process. The measured area is located near the center of the constant temperature water, and its interface is parallel to the implant interface. The center point of the measured area should not deviate by 25mm from the temperature sensing end of the thermometer indicating the test temperature of the constant temperature water tank. 5.2 Use 9 thermocouples to measure the temperature of 9 measuring points in the measured area. The first measuring point is the center point of the measured area, and the remaining 8 measuring points are the 8 vertices of the measured area. The length of the thermocouple at each measuring point in the water tank is not less than 300mm. Note: All thermocouples should be calibrated. The 9 thermocouples should be composed of the same spool of wires so that the difference in their mutual potential below 200C is no more than 0.2℃ when converted into temperature difference.
5.3 Adjust the water temperature so that the water temperature does not deviate from the test requirement temperature by ±2℃. 5.4 Start measuring 1 hour after the water reaches thermal stability. Quickly record the thermoelectric potential of the thermocouples at the 9 measuring points, measure once every 5 minutes (0th, 5th, 10th, 15th, 20th minute), and complete 5 measurements. 6 Calculate temperature deviation
6.1 Calculate regional temperature deviation
Calculate the average value of the thermoelectric potential of the 5 measurements of the 9 measuring points respectively, and convert it into the average temperature of each measuring point by looking up the graduation table. Approved by the Ministry of Machinery Industry on August 21, 1993
Implemented on October 1, 1993
JB/T4278.7-1993
Based on the average temperature of the center point of the measured area, the regional temperature deviation (accurate to 0.1℃) between the average temperature of each measuring point and the average temperature of the center point is calculated according to the following formula.
a,-tt,
Where: a is the spatial temperature deviation of the ith point of the measured space, i=1~8, C; t is the average temperature of the ith point of the measured space, i=1~8, Ct, - is the average temperature of the center point of the measured space, C. Calculation of temporal temperature fluctuation
..--..(1)
Calculate the difference between the highest temperature and the lowest temperature of the 8 vertices of the measured area in 5 measurements according to the following formula to obtain the temporal temperature fluctuation of the measured area (accurate to 0.1℃).
b,binmx—b inhs
In the formula, b,-time temperature fluctuation of the ith vertex, i=1~8, Cbina-maximum temperature of the ith vertex, i=1~8, C; biaim—minimum temperature of the ith vertex, i=1~8, C, 6.3 Calculation of temperature deviation
The temperature deviation is synthesized by the regional temperature deviation and the time temperature fluctuation. The temperature deviation is calculated according to the following formula (accurate to 0.1C), b
In the formula, △ti-temperature deviation of the ith vertex, i=1~8, C; :-—regional temperature deviation of the ith vertex, i-1~8, C; b--time temperature fluctuation of the ith vertex, i=1~8, ℃. 7 Calculation result processing
Check the calculation result of Article 6.3 (keep 1 significant figure). If the maximum temperature deviation meets the requirements of Article 3, the measured area is the working area of ​​7.1
.
7.2 Check the calculation results. If the slope of the measured area does not meet the requirements of Article 3, the position of the measured area in the water crystal can be changed or the size of the measured area can be changed before retesting. In order to ensure that the thermocouple at the original measuring point in the center of the measured area will not exceed 25mm from the sensing end of the water crystal thermometer due to the change of the slope of the measured area, the position of this thermocouple can be moved. At this time, the thermocouple at this measuring point can no longer be located at the center of the measured area after the change.
7.3 This verification method does not include the verification of constant temperature water test temperature indicating instruments (or thermometers). For constant temperature water tanks where the test temperature is displayed by a temperature indicator, and the humidity element of the instrument cannot be located in the working area or the center, the deviation between the temperature indicator and the actual temperature of the working area minus the center at the verification temperature should be given in the verification results. 7.4 For water tanks (water baths) with stirring devices and a volume less than 0.05m3, in addition to using 9-point thermometers to calibrate the working area, a second-class standard thermometer can also be used instead of thermometers to calibrate the measured area. 7.5 A calibration certificate will be issued to qualified thermometers. See Appendix A of JB/T4278.1 for the sample of the calibration certificate. The certificate should indicate the measured temperature and the location and range of the working area.
7.6 The calibration cycle of constant temperature water probes is generally two years. Additional remarks;
This standard was proposed and managed by the Shanghai Cable Research Institute of the Ministry of Machinery Industry, and was drafted by the Shanghai Cable Research Institute of the Ministry of Machinery Industry and others. The main drafter of this standard is Yuan Baifen.
People's Republic of China
Mechanical Industry Standard
Rubber and plastic wire and cable test instrument and equipment verification method Constant temperature water bath
JB/T 4278.71993
Published and issued by the Mechanical Science Research Institute
Printed by the Mechanical Science Research Institute
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Postal Code 100044)
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