JJG 934-1998 γ-ray level meter JJG934-1998 standard download decompression password: www.bzxz.net
This regulation is applicable to the verification of newly manufactured, in-use and repaired γ-ray level meters, including γ-ray level meters for continuous measurement (continuous type) and positioning indication (switch type).

National Metrology Verification Regulation of the People's Republic of China JTG934—1998
Gamma Ray Level Meter
1998—05-12 Issued
1998—12—01 Issued
State Administration of Quality and Technical Supervision
JJG934--1998
Verification Regulation of
Gamma Ray Level Meter
JJG934—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 Emission Metrology Technical Committee Drafting unit: Shanghai Institute of Metrology and Measurement Technology The technical provisions of this regulation shall be interpreted by the drafting unit The main drafters of this regulation:
Chen Jianxin
Tang Fangdong
JJG934-1898
(Shanghai Institute of Metrology and Measurement Technology)
(Shanghai Institute of Metrology and Measurement Technology) 2.
Technical requirements
Verification conditions
Verification items and verification methods
Handling of verification results and verification cycle
Contents of the verification certificate
JJG $34—1998
JJG934—1998
，Verification Procedure for Radiation Level Meters
This procedure is applicable to the verification of radiation level meters newly manufactured, used and repaired, including those used for continuous measurement (continuous type) and positioning indication (switch type). The radiation level meter (hereinafter referred to as the level meter) is mainly composed of a radiation source, a probe, an electric measuring mother component and a material container. According to the principle, it can be divided into three types: transmission type, direct radiation type and reverse radiation type. According to the structure, it can be divided into three types: fixed type, follow-up type and scanning type. ||t t||The level meter measures the position of the material in the container by utilizing the characteristic that the intensity of the radiation received by its deep head changes with the material level. The radioactive source used in the level meter is usually 13Cs or ℃. Question: A continuous level meter refers to a level meter whose output signal can display the continuous change of the material level in the container. A switch level meter refers to a level meter that uses the switch conductance output by the instrument to indicate the height of the container and whether the material being measured exists. The measured material is usually in a solid state (including gas-liquid two-phase state) or in the form of particles or powder. The reading display of the level meter can be digital, pointer or other types. The displayed value can be high or low. Degree, mass and volume. 2. Technical requirements
1. Requirement 1. The material level meter must be clearly marked with the manufacturer, model, serial number and date of production. 1.2 All parts of the material level meter should be intact and the assembly should be reliable. There should be no defects that affect the normal operation. 1.3 The source component shell of the material level meter should have obvious radioactivity marks and source container shielding performance level marks, indicating the nuclide name, activity value and reference date. The source gate must have a safety locking device, the position mark of the source switch should be clear, and the switch action should be flexible and reliable:
2 Continuous material level meter
2. 1 Basic error
The basic error limit of continuous level meter is expressed as relative reference error, and shall comply with the provisions of Table 1 according to the accuracy grade requirements.
Accuracy grade
Basic error limit ()
Basic error limit of continuous level meter
2.2 Repeatability
JJG934—199B
The ratio of the standard deviation of a single measurement of a continuous level meter to its range shall not be greater than 13 of its basic error limit. 2.3 Stability
The short-term stability of the continuous level meter shall not be greater than its basic error limit. 3 Switch type material level meter
The short-term stability of the switch type material level meter meets the requirements of Table 2: Table 2 Stability requirements of the switch type material level meter
Stability level (when)
Switch point "source"
Switch adjustment"
Switch point-
The switch changes state to the corresponding voltage value received by the probe. The switch point of the material level meter is within a certain range. When the output value changes from the on state to the off state and from the off state to the on state, the time required is usually different. **The switch-on error-
-ensures that the switch type material level meter is relatively reliable, and the minimum change in the voltage value received by the probe is required. For any given material level meter, the minimum detection value corresponding to the process change of its sub-error is not a creative determination. It is more likely to be used to measure the density, diameter, etc. of the material being measured. The material level meter shall have a method or device to compensate for the error caused by radiation decay, and the shielding performance of the source container shall comply with the provisions of Table 3. The material level meter shall be accompanied by an instruction manual and a certificate of the last calibration. The first calibration shall be accompanied by an inspection certificate issued by the manufacturer. 3. Passive shielding performance requirements
Maximum full capacity equivalent rate
Outer surface of the engraved container
5 cm from the outer surface of the commercial source
10 m from the outer surface of the high-voltage receiver
1 meter from the outer surface of the source m place
source device
end holding point
evaluated to detector
.1 length main standard
acid pregnant
J:9341998
large dose when apparent rate μSvh
distance from the source container
surface sem
25 (question related)
200 (source related)
surface 0 place
three test conditions
jump away from the source narrow
surface 1 sub 20 Source (Attached to the US)
Source device
Features of the structure
Light source
Active level
Active level
For material level meters displayed by commercial manufacturers, the minimum graduation value of the measuring instrument used to measure the material level shall not be less than 1/3 of the basic error limit of the material level, that is, the corresponding absolute error: 7.2 See standard
For meters with pressure as the display value, the minimum graduation value of the measuring instrument used to measure the material level shall not be greater than 1/3 of the basic error limit of the material level meter, that is, the corresponding absolute error: ? .3 Volume calibration For the level gauge with volume as the display, the volume is measured with a meter and the minimum tap value is not greater than the absolute error corresponding to the basic error limit of the material level. 7.4 Ionization radiation measurement is sufficient, and its measurement precision is not greater than 173 yuan of the cumulative shift limit of the switch point corresponding to the stability level of the material level gauge being tested. Other equipment for calibration. .1 Thermometer: The minimum scale is 0.5, and the measurement range is (-0-+0). .2 Barometer: The minimum scale is 0.1kl, and the measurement range is [86--10f) kPa. 8.3 Simulated test source, its nuclear decay shall be the same as that of the source of the material level meter to be tested. 8.1 Radiation dose rate meter, its performance shall meet the requirements of vehicle radiation protection receiver. Calibration environment conditions
The environmental conditions during calibration shall meet the metrological standards. 10 General calibration
JJG934—1998
Selection items and calibration methods
Nearly plan the appearance of the dynamic test to confirm the magnetic field level meter is in compliance with the cloud tax system. 11.1 Basic error Select 5 measuring points within the range of the material level meter, measure the actual material level of each point in the direction of material rise, and calculate the error value of each measuring point in this direction according to formula (1): D--the error value of the first measuring point: the median value of the material level meter measured by the first measuring point; the average value of the actual material level measured by the next measuring point: R--the basic error. After that, the default error of each measuring point in the next direction can be obtained by the method, and the one with the largest absolute value of the difference among the 10 groups is taken as the basic error of the level meter. 1.2 The basic error is calculated at 174° from the lower end within the effective range of the material level meter measurement. Repeat the oxygen measurement for 10 times, and record the repeatability of the meter according to the formula:
Where: X is the first measured value;
is the average value of the 10 measured values;
R is the range of the material level meter.
11.3 pieces
(X, -X)3 K 100%
Select a fixed measuring point at 1/4 of the effective range of the material level meter, and get a group of readings X (at least 3 times each, and collect the average value), a total of 1, and then calculate the ratio of the single-time deviation to the range of the material level meter according to formula 3), and print it as the stability s of the material level meter.
Wu: X,1--The average of the measured values ​​in the first group: 4
(Xx)×100%
to 10--The average of the measured values ​​in the last group:
R——the range of material level.
12 American material level
12.1 Opening point specification
J.1G 934 --·1998
The method of simulating the test source is to change the distance between the mechanical test source and the material level probe to make the switch output signal jump. When the electric radiation meter detects the positive jump, the electroacoustic measurement at the material meter probe is displayed: Measure once every 6mm or more, and calculate the drift of the open and closed points of each measurement by formula (4): -100
Where: P is the drift of the open and closed point of the measured distance; X is the measured value of the open or closed point of the material level meter for the first measurement: -100
The measured value of the material level meter is the maximum value, which is the open and closed point drift of the material level meter. 12.2 Switch long drift stability
The difference between the switch differential shift and the switch point drift is measured alternately, calculated according to formula (5); 100%
(X; :X)(X
Wherein: P, the differential drift between the primary and secondary measurements; X-the measured value of the material level meter at the second measurement:
, the measured value of the material level meter at the second measurement. The maximum absolute value is the differential drift of the material level meter. 1.3 Shielding performance of source containerWww.bzxZ.net
According to the energy level of the container, use the dose rate specified in Table 3 to measure the dose rate at a certain distance from the source container.
V. Processing of verification results and verification period
14: Verification certificates shall be issued to qualified level meters verified in accordance with this regulation; verification results shall be issued to those who fail the verification. 15. The verification format of the material level meter is 2 lines
1 Verification clause
G934-1998
Verification certificate text Contents
Briefly describe the working voltage of the level meter, the standard instrument used and its accuracy level, and the environmental conditions during calibration, etc., and indicate the time number set for the level meter during calibration and the material to be measured. 2. Calibration results
2.1 Basic error
Describe the accuracy level and effective measurement range of the level meter. 2.2 Repeatability
Describe the pressure measuring points selected for the gravity decay test. 2.3 Stability
Describe the test time,
3 Working state of the level meter
Describe the material type or composition of the level meter during calibration, and the compensation correction for the decay of the radioactive source during calibration,
Additional notes: This calibration procedure has been approved by the National Technical Committee for Ionizing Radiation Metrology: 6
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