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Mechanical Industry Standard of the People's Republic of China
JB/T7392-94
Digital Pressure Gauge
Published on August 23, 1994
Implemented on May 1, 1995
Ministry of Machinery Industry of the People's Republic of China
1 Subject Content and Scope of Application
Mechanical Industry Standard of the People's Republic of China
Digital Pressure Gauge
JB/T7392-94
This standard specifies the product classification, technical requirements, test methods, inspection rules, marking, packaging and storage of digital pressure gauges. This standard applies to all types of digital pressure gauges (hereinafter referred to as instruments) with sensors as pressure-sensitive elements. Reference standards
GB4439 Industrial automation instrument working conditions - vibration GB4451 Industrial automation instrument vibration (sinusoidal) test method GB/T1402 Industrial automation instrument housing dimensions for instrument panel JB/T6239.1 General test methods for industrial automation instruments Common mode and S-mode interference effects JB/T6239.3 General test methods for industrial automation instruments Effects of power supply voltage drop JB/T6239.4 General test methods for industrial automation instruments Effects of short-term power interruption JB/T6239.5 General test methods for industrial automation instruments Influence of transient overvoltage of power supply ZBY002 Basic environmental conditions for transportation and storage of instruments ZBY003 General technical conditions for packaging of instruments ZBN10003.11 Influence of external magnetic field
3 Product classification
3.1 The range of the instrument should be selected from the following basic series (n is an integer or zero) 1.00×10*:1.60×10:(2.0×10):2.5×10:4.00×10°;(6.00×10):6.30×10*. Note: The values in brackets are not recommended. 3.2 Instruments are divided into the following types according to their structural types:
a. Separate type: The sensor and the secondary instrument are connected by a cable: b. Integral type: The sensor and the secondary instrument are integrated. 3.3 The instruments are classified into the following types according to the usage:
a. Panel mounted: its dimensions shall comply with the provisions of GB/T1402; b. Portable: its dimensions shall comply with the provisions of relevant standards or the manufacturer. 3.4 The following specifications are recommended for the instrument connectors: M10×1; M14×1.5; M20×1.5.
Approved by the Ministry of Machinery Industry on August 23, 1994
Implemented on May 1, 1995
3.5 The instrument accuracy levels are divided into five levels: ().05, 0.1, 0.2, 0.5, 1. 4 Technical requirements
4.1 Normal working conditions
The normal working conditions of the instrument shall comply with the provisions of Table 1. Precision
Relative humidity
Atmospheric pressure
Power supply voltage
Power supply frequency
Harmonic content
Installation position
External magnetic field
Environmental vibration
4.2 Reference working conditions
JB/T7392-94
Reference working conditions
0.05, 0.1, 0.2
20 ±2
86~106
20 ±5
Allow deviation of ±1%
Allow deviation of ±1%
50±1%
External magnetic field is so small that it can be ignored
No vibration source around the test environment
The reference working conditions of the instrument shall be as specified in Table 1. 4.3 Basic error
The basic error limit of the instrument is specified in Table 2. Table 2
Accuracy grade
Basic error limit
(Expressed as a percentage of the range)
4.4 Hysteresis
The hysteresis of the instrument shall not be greater than the absolute value of the basic error limit. 4.5 Repeatability
0.05, 0.1, 0.2
Operating conditions
86~106
220±10%
220±15%
According to the manufacturer's regulations
50±1%
Determined by the manufacturer or determined by negotiation with the user
Should not exceed the regulations of VH2 level in GB4439
Should not exceed the regulations of VH3 level in GB4439
JB/T7392-94
The repeatability of the instrument shall not be greater than the absolute value of the basic error limit. 16 Zero drift
The zero drift of the instrument shall not be greater than 1/2 of the absolute value of the basic error limit within 1 hour. 47 Indication fluctuation
The indication fluctuation of the instrument shall not be greater than 1/3 of the absolute value of the basic error limit. 4.8 Alternating load
The instrument shall be subjected to a sinusoidal alternating load test as specified in Table 3. After the test, its basic error, hysteresis and repeatability shall meet the requirements of Articles 4.3, 4.4 and 4.5 of this standard.
Upper limit of measuring range
100~160
4.9 Overload
Alternating amplitude
Expressed as % of the upper limit of the measuring range
The instrument shall be able to withstand the overload requirements specified in Table 4. Table 4
Upper limit of measurement range
100~160
4.10 Insulation performance
4.10.1 Insulation resistance
Load value
Expressed as % of upper limit of measurement range
Number of alternations
Under reference working conditions, the insulation resistance between the terminals of the meter and between the terminals and the ground shall not be less than 20Mn. 4.10.2 Insulation strength
Under reference working conditions, the terminals of the meter shall be able to withstand the AC voltage withstand test of 1 min specified in Table 5. Table 5
Power supply voltage
60~130
130~250
4.11 Temperature influence
4!1 Thermal zero drift
Test voltage value
JB/T7392-94
When the ambient temperature deviates from the reference working condition temperature, the zero drift of the instrument shall not exceed 10% of the absolute value of the basic error limit for every change of 1T. 4.11.2 Thermal sensitivity drift
When the ambient temperature deviates from the reference working condition temperature, the sensitivity drift of the instrument shall not exceed 10% of the absolute value of the basic error limit for every change of 1T.
4.12 Power supply voltage change
When the power supply voltage changes within the range specified in Table 1, the indication of the instrument shall still meet the requirements of the basic error limit. 4.13 Influence of external magnetic field and power distortion 4.13.1 Influence of external magnetic field
Under the influence of external magnetic field with a rated frequency of 50Hz and a strength of 400A/m, the change of the value indicated by the instrument shall not exceed 1/2 of the absolute value of the basic error limit.
4.13.2 Influence of transient overvoltage of power supply
For AC powered instruments, the influence of transient overvoltage of power supply on the instrument can be determined by consultation between the user and the manufacturer in accordance with JB/T6239.5.
4.13.3 Influence of short-term interruption of power supply
The influence of short-term interruption of power supply on the instrument can be determined by consultation between the user and the manufacturer in accordance with JB/T6239.4. 4.13.4 Influence of power supply voltage drop
For AC powered instruments, the influence of power supply voltage drop on the instrument can be determined by consultation between the user and the manufacturer in accordance with JB/T6239.3.
4.13.5 Common mode and serial mode interference effects
For separate instruments, the common mode and serial mode interference effects can be determined by negotiation between the user and the manufacturer. 4.14 Working environment vibration resistance
The instrument should be able to withstand the working environment vibration test specified in Table 1. In the vibration test, the indication of the instrument shall not be greater than the basic error limit: After the vibration test, the basic error, hysteresis and repeatability of the instrument shall meet the requirements of Articles 4.3, 4.4 and 4.5 of this standard. 4.15 Transportation environment resistance performance
The instrument shall comply with the provisions of ZBY002 under packaging conditions. Among them: a. Low temperature is -40℃
b. Free fall height is 50mm.
4.16 Warm-up time
The recommended warm-up time for the instrument is 15min, 30min and 60min. 4.17 Additional outputs
This standard recommends the following for instruments with additional outputs:a. Standardized analog DC signals shall be used as the output analog signals:b. The output interface, instructions or other signal forms and corresponding technical requirements shall be given. 4.18 Cable requirements
For separate instruments, the maximum allowable length of the cable connecting the sensor and the display shall be specified. 4.19 Appearance
a. The appearance of the instrument shall be smooth and free of coating shedding, scratches, damage, etc.;b. The digital display shall have complete strokes and uniform brightness;c.All markings should be clear and correct. 5 Test method
5.1 Test conditions
According to the reference working conditions in Table 1.
52 Standard instrument
JB/T7392-94bzxZ.net
The absolute value of the absolute error limit of the standard pressure source should not be greater than 1/3 of the absolute value of the absolute error limit of the instrument under test. Note: For 0.05 short and 0.1 short gauges, the pure value of the absolute error of the standard pressure source is allowed to be no greater than 1/2 of the absolute value of the absolute error limit of the instrument under test.
5.3 Test requirements
5.3.1 Before the test, the instrument should be preheated according to the preheating time specified by the manufacturer. The instrument can also be pre-adjusted according to the manufacturer's regulations. However, the pre-adjustment time should be included in the preheating time.
5.3.2 The test points should be evenly distributed within the instrument range. For instruments of level 0.05, 0.1 and 0.2, the number of test points shall be at least 10 (including the upper and lower limits of the measuring range); for instruments of level 0.5 and 1, the number of test points shall be at least five (including the upper and lower limits of the measuring range).
During the test, the input pressure shall approach the test points in the same direction to ensure that there is no obvious fluctuation in the input pressure and no overshoot occurs at any test point.
5.4 Basic error test
Steady increase the load (positive stroke) from the lower limit value to measure the specified test point to the upper limit value; then steadily reduce the load (reverse stroke) to measure the specified test point to the lower limit value. Calculate the error at each test point according to the following formula. 4=Ys-Y
Dan×100%
Where: 公—basic error, %;
Ys——output indication, Pa;
Y-input nominal value, Pa:
Y—range (difference between the upper and lower nominal values of the measuring range), Pa. 5.5 Hysteresis test
+++(1)
In the test of 5.4, compare the output indications of the positive and reverse strokes of each test point, take the largest difference, and express it as a percentage of the range output.
5.6 Repeatability test
After at least three test cycles of the test of 5.4, compare the indications of the same stroke of each test point, take the largest difference, and express it as a percentage of the range output.
5.7 Zero drift test
When the instrument input pressure is zero, record the initial indication of the instrument (for instruments with zero adjustment device, the initial indication can be adjusted to equal), then record the indication every 15 minutes until 1 hour. The value with the largest absolute value of the difference between each indication and the initial indication, expressed as a percentage of the range, is the zero drift value of the instrument.
5.8 Indication fluctuation test
Input 80% of the upper limit of the measuring range into the instrument. After the pressure system stabilizes, observe the change of the indication within 10 minutes of the instrument, and read the difference between the maximum and minimum indication changes △P. △P/2 is taken as the fluctuation value of the instrument indication. 5.9 Alternating load test
Install the instrument on a sinusoidal pressure device that can generate a frequency of 60 ± 5 times/minute and an amplitude of 20% to 80% of the range. After 20,000 cycles of testing as specified in Table 3, check the basic error, hysteresis, and repeatability. 5.10 Overload test
Carry out overload test according to the requirements of Article 4.9 of this standard. After unloading the pressure, recover for 30 minutes, and then check the basic error, hysteresis and repeatability. 5.11 Insulation performance test
5.11.1 Insulation resistance test
For instruments powered by AC power, use a high resistance tester to measure the insulation resistance at a DC voltage of 500V; for instruments powered by DC power JB/T7392-94
, use a high resistance tester to measure the insulation resistance at a DC voltage of 100V. 5.11.2 Insulation strength test
Put the instrument in the high voltage test bench to test the insulation strength of the instrument. During the test, the voltage is steadily increased from zero to the test voltage value specified in Table 5 and maintained for lmin, and then the voltage is steadily reduced to zero. 5.12 Temperature influence test
Put the instrument in the temperature test box, gradually increase (decrease) the temperature to the upper (lower) limit temperature of the normal working conditions specified in Table 1, and make the instrument bear a load not less than 80% of the upper limit value. After the temperature stabilizes, keep it warm for 2 hours, and then test the zero point indication and the upper limit indication of the measuring range respectively. Thermal zero drift 0. Calculate according to formula (2): Thermal sensitivity drift is calculated according to formula (3). Yo(t)-Y(t) ×100% .-
Y(tt,)
Where:
Temperature before temperature influence test.℃:
The high (low) temperature specified in Table 1, seven; Y. (t.)——The average value of zero point indication at temperature t, Pa; Y (tz)——The zero point indication after keeping warm for 2 hours at temperature t, Pa. . - Yn(c)-Ya(c)
2×100%
Y(tz-t)
Where: Y(ti)——the difference between the average value of the upper limit indication and the average value of the lower limit indication of the measurement range at temperature t, Pa: Ya(ts)—the difference between the upper limit indication and the lower limit indication of the measurement range at temperature ts, Pa. 5.13 Power supply voltage change test
Raise and lower the power supply voltage to the upper and lower limits of the normal working conditions in Table 1 of this standard respectively, and check the indication of the instrument. 5.14 External magnetic field influence and power supply distortion shadow test 5.14.1 External magnetic field influence test
The external magnetic field influence test is carried out in accordance with ZBN10003.11. 5.14.2 Power supply transient overvoltage influence test
The power supply transient overvoltage influence test is carried out in accordance with JB／T6239.5. 5.14.3 Power supply short-term interruption impact test
Power supply short-term interruption impact test is carried out in accordance with JB/T6239.4. 5.14.4 Power supply voltage drop impact test
Power supply voltage drop impact test is carried out in accordance with JB/T6239.3. 5.14.5 Common mode and series interference impact test Common mode and series interference impact test is carried out in accordance with JB/T6239.1. 5.15 Working environment vibration resistance test
During the test, the instrument should be subjected to a load of 50% of the upper limit of the measuring range. -(2)
+（2)
The test is carried out in accordance with the requirements of the frequency, fixed frequency test time and number of sweep frequency test cycles of Class 1A in GB4451. For instruments of Class 0.05, Class 0.1 and Class 0.2, the displacement amplitude of the test is 0.035mm; for instruments of Class 0.5 and Class 1, the displacement amplitude of the test is 0.075mm. During the test, check the basic error of the instrument; after the test, check the basic error, hysteresis and repeatability of the instrument. 5.16 Test for resistance to transportation environment
The test shall be carried out in accordance with the provisions of ZBY002 and the requirements of Article 4.15 of this standard. After the test, check the basic error, hysteresis and repeatability of the instrument. 517 Appearance inspection
First visually inspect the appearance of the instrument and the necessary signs, then turn on the power and check the digital display strokes and brightness of the instrument. 6 Inspection rules
6.1 Factory inspection
6.1.1 Inspection items
a, basic error;
b, hysteresis;
c. Insulation performance;
d. Appearance.
6.1.2 Sampling and judgment rules
JB/T7392-94
The inspection department of the manufacturer shall inspect each instrument according to the factory inspection items. If one item of an instrument fails to meet the standards, the instrument is considered as an unqualified product. Only instruments that meet all factory inspection items can be considered as qualified products. Instruments that have passed the inspection must be accompanied by a product certificate before they can leave the factory.
6.2 Type test
6.2.1 Test items
When any of the following situations occurs, the type test shall be carried out in accordance with all the technical requirements of this standard. a. Newly developed products;
b. When there are major changes in design, process, materials and components; c. Continuous production for more than two years;
d. When a product that has been discontinued is produced again. 6.2.2 Sampling and judgment rules
Three units shall be randomly selected from the qualified products as the test units for the type test. In the test, in both cases a and b, if one of the prototypes fails one item, the test shall fail. In the cases of c and d, if one item of a prototype fails, it is necessary to double the number of samples for retesting. After all test items of the test prototype are qualified, the type test is passed, otherwise, the type test is not passed.
7 Marking, packaging, storage
7.1 Marking
The instrument should have a nameplate, which should indicate:
Manufacturer and trademark;
b. Instrument name and model;
c. Accuracy grade and measuring range:
d. Production date and product number.
7.2 Packaging
The packaging of the instrument shall comply with the provisions of ZBY003. Among them, the packaging protection type is determined by the manufacturer. 7.3 Storage
The instrument should be stored in a ventilated, dry, and non-corrosive gas room. Additional remarks:
This standard was proposed and coordinated by the Xi'an Industrial Automation Instrumentation Research Institute. This standard was drafted by the Xi'an Industrial Automation Instrumentation Research Institute. The main drafters of this standard are: Luo Juan, Wang Zhenzhong, Li Baokang, and Yang Shuitai. People's Republic of China
Machinery Industry Standard
Digital Pressure Gauge
JB/T7392-94
7392-94
Published by the Instrument and Instrument Technology and Economic Research Institute of the Ministry of Machinery Industry; Beijing Machinery Enterprise Association Printing and Financial Service Department Printing
Published by the Instrument and Instrument Technology and Economic Research Institute of the Ministry of Machinery Industry*
First edition in March 1996
Print run: 240 copies
First printing in March 1996
Cost: RMB 9.00
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