JJG 935-1998 γ-ray thickness gauge JJG935-1998 Standard download decompression password: www.bzxz.net
This procedure is applicable to the calibration of γ-ray thickness gauges that are newly manufactured, in use and after repair.

National Metrology Verification Regulation of the People's Republic of China. HJG935--1998
Y-Ray Thickness Gauge
Issued on 1998-05-12
Implemented on 1998-12-01
Issued by the State Administration of Quality and Technical Supervisionbzxz.net
JJG935--1998
Verification Regulation of
Y-Ray Thickness Gauge
JJG935--1998
This verification regulation was approved by the State Administration of Quality and Technical Supervision on May 12, 1998, and came into effect on December 1, 1998.
Responsible unit: National Ionization Radiation Metrology Technical Committee Drafting unit: Beijing Institute of Metrology Beijing Municipal Bureau of Technical Supervision
The drafting unit of the technical provisions of this regulation is responsible for interpreting the main drafters of this regulation:
Huang Hongliang
Qian Xufeng
Guo Hongtao
JJG935-—1998
(Beijing Institute of Metrology)
(Beijing Technical Supervision Bureau)
(Beijing Institute of Computing Science)
Technical requirements
Verification items
Verification methods
Verification results and verification period
Appendix 1
Record 2
Verification certificate content
JJG935—1998
【2】
JJG 935—1998
Verification procedures for Y-ray thickness gauges
This procedure is suitable for new products, products that are in use or after repair. 1. Overview
The X-ray thickness gauge is a non-transmitting measuring instrument. It usually adopts the transmission type, where the radiation source and the detector are respectively on both sides of the material to be measured, using? The shape of the material to be measured is usually sheet or strip. Its thickness can be directly displayed or indicated by deviation, and the length variable unit can be used for measurement. The measured value can also be directly displayed and divided into different grades. The ray thickness meter (hereinafter referred to as the thickness meter) consists of the source, detector and measuring parts: 2. Technical requirements
1 Appearance
1.1 The thickness meter should be marked with the manufacturer, (trademark), instrument number, factory date and instrument manufacturing license mark and number
2 All parts of the thickness meter should be intact, the assembly should be firm, and no defects that affect the sealing performance are allowed: 1.3 The source container of the thickness meter should have radioactive markings and comply with the relevant regulations of the total radiation source tube. The source should have a locking device and the markings on the closed position should be clear: 2 Basic error
Sequence thickness meter accuracy classification, its basic error limit should comply with the provisions of Table 1, Table 1 Basic error limit of thickness meter
Uncertainty level
Error % || tt||For various thickness gauges, each of which may have different accuracy, the accuracy grade of the thickness gauge used shall be the accuracy grade of the thickness gauge
For thickness gauges with thickness deviation, the relative difference between the deviation indication and the actual deviation value within the three-stage deviation indication shall not exceed 3 of the basic error limit. 3Resilience
Within the effective measurement range of the thickness gauge, a test sample is measured 10 times continuously, and the relative standard deviation of the single pressure measurement value shall not exceed 2/3 of the basic error limit of the corresponding grade. 4Stability
JJG935—1996
Within the effective measurement range of the thickness gauge, the change of the display or output signal relative to the initial value within 10H shall not exceed the basic error limit of the corresponding grade. 5Response time
The response time of the thickness gauge shall be given by the manufacturer. 6. The screen performance of the source container of the radioactive product should be checked. When the source is closed, the maximum radiation rate at 5 cm from the outer surface of the source container or 1 m from the internal radiation source should comply with the relevant regulations of Taiwan. 3. Verification conditions
7. Thickness standard plate
The standard sample composed of the same type and material as the material to be measured should be selected. The measurement uncertainty of its thickness should not exceed 1/3 of the basic error limit of the thickness gauge to be tested. The thickness of the standard sample should be within the effective measurement range of the thickness gauge (at least 5 points), and the thickness of the thickest and the thinnest sample should be close to the upper and lower limits of the thickness gauge's measurement range, respectively. 8. Other inspection equipment
7. Auxiliary radioactive plate equivalent rate receiver:
display or recorder.
9 Calibration environmental conditions
The atmospheric environment and power grid conditions for calibration shall comply with the provisions in the user manual of the thickness gauge. IV.
Calibration items and calibration methods
10 Acceptance inspection
Confirm that the thickness gauge to be inspected meets the following conditions through reading and power-on inspection: 10.1 The appearance of the thickness gauge complies with the requirements of Article 1 of this regulation. 10.2 The function keys, buttons and switches of the thickness gauge can effectively operate normally according to the provisions in the user manual. In the following calibration, the measuring head of the thickness gauge remains fixed. 10.3 Thickness gauges with microprocessors shall be able to operate normally according to the prescribed procedures. 11 Basic error
11.1 For thickness gauges that directly display thickness values, 11.1.1 Use standard scales to select at least 5 evenly distributed calibration points (including:, compensation limit) within the effective measuring range of the thickness gauge for calibration.
I,1.2 The number of measurements for each calibration point shall be no less than 3 times. The relative deviation of the calibration point shall be calculated by the following formula: 11.1.3
Area - X × 100%
or medium, the average of the values ​​indicated by the meter; x
the actual value of the limit of the standard plate,
J.IG 935—1998
11.1.4 The maximum relative screening error E of the calibration point shall meet the requirements specified in Case 2. 11.2 For thickness gauges showing deviations, 11.2.1 Within the full range of deviation, measure four standard plates evenly distributed at the original depth. 11.2.2 Place a standard plate of the same set depth H on the measuring or measuring position, and subtract one integer to give the given deviation. 11.2.3 The thickness value H of the standard plate is equal to the nominal value of the set thickness plus the indicated difference value. Read the deviation value on the deviation display. If the difference is expressed as a fraction, it should be converted into a serial value. 11.2.4 Calculate the error of each point using the following formula: Where: Hα - deviation indication: Hα - set depth; H - standard plate thickness value, IHaj.Ha - Halix100% Hu - 11.2.5 The maximum error of the service inspection point shall meet the requirements specified in Article 3. 12: Validity
12.1 This calibration shall be within the effective measurement range of the thickness gauge. 12.2 The response time of the thickness gauge is the value selected. (2)
12.3 For the same sample, repeat the measurement 1 time, and the time limit between the two adjacent readings shall be less than 3 times the constant of the thickness gauge. The sum of the single measurement values ​​is the standard deviation 11
Where: X - first reading:
A The arithmetic mean of the single measurement values:
3 Width
(X -X)
13.1 In the effective measurement range, select a sample with a thickness value, (3)
13.2 Within 10 hours, record the group of indications every 3 minutes (3 times per group, take the average value), and calculate the stability calibration by the following formula:
Where: X. is the measured value;
is the second measured value.
14 Response time
X:-xilc 100%
14.1 During the calibration, the step center of the stroke is 30% of the given range and 80% of the stroke. (4)
JJG935—1998
14.2 Place a standard plate on the measuring surface of the thickness gauge, then quickly pull or remove the standard plate to create a step signal. Use an oscilloscope or recorder to measure the relative change of the step signal at the analog signal output end. The time required for the first time to reach 63.2% of the final change,
take the average value of the three measurement results as the response time of the thickness gauge. 4.3 The time required for the measured object to produce a step change should not be greater than one-tenth of the measured response time value. 15 Radiation dose rate
Use the radiation dose rate to measure the surrounding dose at 5cm from the source container surface or 1m from the radiation inside:
5 Verification results and verification period
16 Verification result processing
The qualified X-ray thickness meter will be issued with a verification certificate; the unqualified one will be issued with a verification result notice: 17 Verification period
17.17 The calibration cycle of the X-ray thickness gauge is 2 years. 17.2 Cycle timing. Items 10 to 12 are mandatory inspection items. Items 13 and 14 can be calibrated according to the usage and needs.
18 When sent for inspection, the thickness gauge instruction manual and the first calibration certificate shall be attached. The thickness gauge for the first calibration shall be attached with the factory inspection certificate
Appendix 1
1 X-ray thickness assessment
JJC935—1998
A device that carries a radioactive source and uses its? X-rays to non-destructively measure the thickness or unit area mass of the material being measured, also known as a X-ray thickness gauge. The actual measurement of the thickness gauge is the average mass per unit area of ​​the material being measured. Only when the effective atomic number and density of the measured material remain unchanged, the output signal can reflect the geometric thickness? Radiation-avoidance sequential thickness assessment
A device that uses ionizing radiation that passes through the measured material to measure the thickness of the measured material. The radiation source and detector are respectively attached to the two sides of the material to be tested. 3 Source components The components used to generate and control the required radiation, usually composed of radiation source, source container, source detector and some functional units. The switch that controls the radiation source to turn on and off the useful radiation beam. 5 Basic error limit The maximum allowable value of the basic error of the instrument. 6 Response time The time from the cascade change of the measured value to the change of the output signal, the first time to reach 63.2% of the final change. Appendix 2 Verification clauses JJC935-1998 Contents of the verification certificate The accuracy level of the standard plate used and the environmental conditions of the verification, etc. 2 Verification results 2.1 Basic error Describe the effective measurement range and accuracy level of the thickness gauge. 2.2 Repeatability
Describe the selected measuring points and the response time of the thickness gauge, 2.3 Stability
Describe the measuring points and the test time,
2.4 Differential linearity
Describe the effective measuring range.
2.5 Response time
Describe the measuring points.
2.6 Radiation dose rate
Additional note: This calibration procedure has been approved by the National Ionization Radiation Meter Technical Committee. 6
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