Some standard content:
National Metrology Verification Regulation of the People's Republic of China JJG875-2005
Digital Pressure Gauges
Promulgated on 2005-12-20
Implementation on 2006-06-20
Promulgated by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China JJG875—2005
Verification Regulation of
Digital Pressure Gauges
JJG875—2005
Replaces JJG875—1994
This regulation was approved by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China on December 20, 2005, and came into effect on June 20, 2006.
Responsible unit:
Main drafting unit:
Participating drafting unit:
National Pressure Metrology Technical Committee
China Testing Technology Research Institute
Shanghai Measurement and Testing Technology Research Institute
Beijing Conster Technology Co., Ltd.
Huayang Measuring Station of Southwest Oil and Gas Field Branch
This regulation entrusts the National Pressure Metrology Technical Committee to be responsible for interpreting this regulation. Main drafter:
Li Zubin||tt ||Tu Limeng
Participating drafter:
JJG875—2005
(China Testing Technology Research Institute)
(Shanghai Institute of Metrology and Testing Technology) (China Testing Technology Research Institute)
(Beijing Conster Technology Co., Ltd.) (Huayang Measuring Station of Southwest Oil and Gas Field Branch) Scope
3 Measurement performance requirements
Maximum allowable error
Return error
Zero drift
Stability
Static pressure zero error
Additional functions
General technical requirements
4.2 Insulation resistance
5 Control of measuring instruments
Verification conditions
Verification items
Verification methods
5.4 Processing of verification results
Verification cycle
Appendix A
Appendix B
Appendix ℃
Appendix D
Verification record format of digital pressure gauge||tt| |Verification certificate (inner page) format
JJG875—2005
Verification result notice (inner page) format
Correction method for additional error caused by height difference of working medium (1)
1 Scope
JJG875—2005
Verification procedure for digital pressure gauge
This procedure applies to the initial verification, subsequent verification and in-use inspection of digital pressure gauges (hereinafter referred to as pressure gauges) with a range of (-0.1~250)MPa.
2 Overview
Digital pressure gauges are pressure gauges that use digital display to display the measured pressure value. They can be used to measure gauge pressure, differential pressure and absolute pressure. The working principle is shown in Figure 1. The measured pressure acts on the pressure sensor through the pressure transmission medium. The pressure sensor outputs the corresponding electrical signal or digital signal, which is directly displayed on the display after being processed by the signal processing unit.
Measured pressure
Sensor
Processing unit
Working power supply
Figure 1 Working principle of digital pressure gauge
Pressure gauges can be divided into integral type and separated type according to their structure. Pressure gauges can be divided into single-function type and multi-function type according to their functions: a) Single-function pressure gauges only have the function of measuring pressure; display
b) In addition to the function of measuring pressure, multi-function pressure gauges also have the additional function of measuring non-pressure parameters (such as voltage, current, etc.).
3 Metrological performance requirements
3.1 Maximum allowable error
The accuracy grade and maximum allowable error of the pressure gauge are shown in Table 1. Table 1 Accuracy grade and maximum allowable error
Accuracy grade
Maximum allowable error
(Expressed as a percentage of the range)
3.2 Return error
The return error of the pressure gauge shall not be greater than the absolute value of the maximum allowable error. 0.2
3.3 Zero drift
JJG875—2005
The zero drift of the pressure gauge (excluding absolute pressure gauge) shall not be greater than the absolute value of the maximum allowable error within 1 hour. 3.4 Stability
For pressure gauges with an accuracy level of 0.05 or above, the change in indication between two adjacent calibration cycles shall not be greater than the absolute value of the maximum allowable error.
3.5 Static pressure zero error
The static pressure zero error of the differential pressure gauge shall be the absolute value of the maximum allowable error. 3.6 Additional functions
The metrological performance of the additional functions of non-pressure parameters of the pressure gauge shall be subject to the technical documents provided by the manufacturer. 4 General technical requirements
4.1 Appearance
4.1.1 The structure of the newly manufactured pressure gauge should be firm, and the plating and coating of the exposed parts should be smooth and should not have peeling or scratches. Function keys such as switches, knobs, and connectors should be intact and firm. The pressure gauge in use and after repair should not have defects that affect its measurement performance.
4.1.2 The nameplate or appropriate position of the pressure gauge should indicate the product name, model, specification, measurement range, accuracy level, manufacturing unit (trademark), factory number, manufacturing year and month, and the mark (number) of the manufacturing measurement instrument license, etc., and they should be clearly legible.
4.1.3 The pressure input port of the pressure gauge used for differential pressure measurement should have high pressure (H) and low pressure (L) signs. 4.1.4 The pressure gauge used for absolute pressure measurement should have an absolute pressure sign or symbol. 4.1.5 The digital display should have complete strokes and no missing strokes should appear. 4.2 Insulation resistance
Under the calibration environment conditions, the insulation resistance between the power supply terminal of the pressure gauge and the housing should not be less than 20MQ. 5 Control of measuring instruments
Control of measuring instruments includes initial calibration, subsequent calibration and in-use inspection. 5.1 Calibration conditions
5.1.1 Standard instruments
5.1.1.1 The standard instruments for pressure gauge calibration can be selected from the following instruments: a) Piston pressure gauge (including single and double piston pressure vacuum gauges); b) Float pressure gauge;
c) Piston pressure vacuum gauge with balanced liquid column; d) Liquid pressure gauge;
e) Digital pressure gauge.
5.1.1.2 The measurement range of the selected pressure standard instrument should be greater than or equal to the measurement range of the pressure gauge. For digital pressure gauges above level 0.05 (including level 0.05), the maximum allowable absolute error of the selected pressure standard shall not be greater than one-half of the maximum allowable absolute error of the digital pressure gauge; for digital pressure gauges below level 0.05, the maximum allowable absolute error of the selected pressure standard shall not be greater than one-third of the maximum allowable absolute error of the digital pressure gauge 5.1.2 Auxiliary equipment 5.1.2.1 Insulation resistance meter (megohmmeter): DC 100V, DC 500V, level 10. 5.1.2.2 Pressure source: gas cylinder, manual pressure (vacuum) pump, air compressor, vacuum pump, etc. 5.1.3 Calibration environmental conditions 5.1.3.1 Ambient temperature: (20±2)℃ for pressure gauges of level 0.1 and above; (20±5)℃ for pressure gauges of level 0.2 and below.
5.1.3.2Relative humidity: not more than 85%. 5.1.3.3There should be no obvious mechanical vibration and external magnetic field (except the geomagnetic field) near the standard instrument and the pressure gauge to be tested.
5.2Verification items
The list of verification and inspection items for pressure gauges is shown in Table 2. The verification items for additional functions are determined according to needs. Table 2 List of verification and inspection items
Verification items
4.1Appearance
4.2Insulation resistance
3.3Zero drift
3.4Stability
3.5Static pressure zero
3.1Indication error
3.2Return error
First verification
Subsequent verification
Note: In the table, "+" indicates items to be inspected, and "_" indicates items that may not be inspected. 5.3 Verification method
5.3.1 Preparation and requirements before verification
5.3.1.1 The pressure gauge should be placed in the verification environment for 2 hours before verification. 5.3.1.2 The indication error of the pressure gauge should be connected as shown in Figure 2 and powered on for preheating. In-use inspection
Select the working medium for verification according to the actual working medium of the pressure gauge. When the working medium is gas, 5.3.1.3
During calibration, the pressure medium should be clean, non-corrosive gas; when the working medium of the pressure gauge is liquid, the pressure medium can be liquid or clean, non-corrosive gas during calibration; when the pressure gauge explicitly requires oil-free, oil-free measures should be taken.
5.3.1.4 Before calibration, the calibration device or pressure gauge should be adjusted to make the pressure points of the two on the same horizontal plane as much as possible. When the pressure points of the two are not on the same horizontal plane, the additional calibration error caused by the height difference of the working medium should not be greater than one tenth of the maximum allowable error of the pressure gauge. Otherwise, additional error correction should be performed. The correction method is shown in Appendix D. 5.3.1.5 Selection of calibration points and number of calibration cycles. For pressure gauges with an accuracy level of 0.05 or above, the calibration points shall be no less than 10 points (including the zero point); for pressure gauges with an accuracy level of 0.1 or below, the calibration points shall be no less than 5 points (including the zero point). The selected calibration points shall be evenly distributed within the full range; for pressure gauges with an accuracy level of 0.05 or above, the number of calibration cycles for pressure increase and pressure reduction (or evacuation and pressure increase) shall be two; for pressure gauges with an accuracy level of 0.1 or below, the number of calibration cycles shall be one.
5.3.1.6 Before the indication calibration, one or two pressure increase (or evacuation) tests shall be performed. During the verification, the pressure increase (or evacuation) and pressure reduction (or pressure increase) should be smooth to avoid shock and overpressure. At each verification point, the pressure value should be stabilized before reading, and records should be kept.
5.3.2 Appearance inspection
The requirements of 4.1.1 to 4.1.4 should be checked by visual observation, and the requirements of 4.1.5 should be checked by power-on.
5.3.3 Insulation resistance verification
Disconnect the power supply, turn on the power switch of the pressure gauge, and use an insulation resistance meter to measure the insulation resistance between the power terminal and the casing.
Note: For pressure gauges powered by AC power, use an insulation resistance meter with a DC output of 500V; for pressure gauges powered by DC power, use an insulation resistance meter with a DC output of 100V. 5.3.4 Zero drift
After power-on preheating, under atmospheric pressure, if the pressure gauge has a zero adjustment device, the initial value can be adjusted to zero, and the displayed value can be recorded every 15 minutes until 1 hour. Among the differences between each displayed value and the initial displayed value, the value with the largest absolute value is the zero drift error.
5.3.5 Stability
After power-on preheating, without any adjustment (if there is a zero adjustment device, the initial value can be adjusted to zero), the pressure gauge should be calibrated for one cycle of forward and reverse strokes, and records should be made. The forward and reverse stroke indication error △pw of each calibration point should be calculated according to formula (1). The absolute value of the difference between the indication error △pw and the indication error Ap of the corresponding positive and negative strokes of each calibration point on the calibration certificate of the previous cycle is the indication stability between two adjacent calibration cycles, which is calculated according to formula (2): △pw=PD-Ps
AW=1pw-Apl
Wherein: Apw is the difference between the indication of each calibration point of the pressure gauge and the standard value, Pa, kPa or MPa; PD
is the indication of the positive and negative strokes of each calibration point of the pressure gauge, Pa, kPa or MPa; (1)
JJG875—2005
p,——the standard indication of each calibration point of the standard instrument, Pa, kPa or MPa; △W is the indication stability of the pressure gauge between two adjacent calibration cycles, Pa, kPa or MPa; Ap is the difference between the indication of the positive and negative strokes of each calibration point on the calibration certificate of the previous cycle and the standard value, Pa, kPa or MPa.
5.3.6 Indication error
5.3.6.1 Verification of indication error
a) After the periodic indication stability verification, if the pressure gauge indication is found to be out of tolerance, increase the pressure (or evacuate) to the full scale of the pressure gauge and compare it with the standard pressure value. Adjust the pressure gauge indication to the optimal value through the manual or automatic adjustment mechanism of the pressure gauge, and then conduct the indication error verification; if the pressure gauge indication is within the qualified range, the pressure gauge indication should also be adjusted to the optimal value, and then conduct the indication error verification (the pressure gauge of grade 0.1 and below can adjust the pressure gauge indication to the optimal value during pre-pressure.
b) Calculation of indication error. The indication error of the pressure gauge is calculated according to formula (3): Ap = PR-Ps
Where: △p——indication error of each calibration point of the pressure gauge, Pa, kPa or MPa; PR—indication of the positive and negative strokes of each calibration point of the pressure gauge, Pa, kPa or MPa; p. Standard indication of each calibration point of the standard instrument, Pa, kPa or MPa. 5.3.6.2 Verification of indication error of differential pressure gauge a) Verification of static pressure zero error
Connect the high pressure end (H) and low pressure end (L) of the one-way differential pressure gauge or the two-way differential pressure gauge, apply 100% of the rated static pressure, and read the static pressure zero indication after the pressure stabilizes. Perform three consecutive verifications. b) Verification of indication error of one-way differential pressure gauge The low pressure end (L) is connected to the atmosphere, and the high pressure end (H) is connected to the verification device. The indication error verification and indication error calculation are carried out according to 5.3.6.1.
c) Verification of indication error of bidirectional differential pressure gauge: First, let the low pressure end (L) pass to the atmosphere and connect the high pressure end (H) to the verification device; then let the high pressure end (H) pass to the atmosphere and connect the low pressure end (L) to the verification device. Verification of indication error and calculation of indication error shall be carried out in accordance with 5.3.6.1. 5.3.7 Verification of return error
The return error can be calculated using the data of the indication error verification. The absolute value of the difference between the forward and reverse stroke indications at the same verification point is taken as the return error of the pressure gauge. 5.3.8 Verification of additional functions
The verification of additional functions of the pressure gauge shall be carried out in accordance with the corresponding metrological verification procedures. 5.4 Handling of verification results
The pressure gauge that has been verified is qualified if its metrological performance and general technical requirements meet the requirements of this regulation, and a verification certificate (format see Appendix B); if one item does not meet the requirements of this regulation, it is unqualified, and a verification result notice (format see Appendix C) is issued, and the unqualified items and contents are noted; when the change in indication between two verification cycles is greater than the absolute value of the maximum allowable error, the pressure gauge that has passed the verification after debugging shall be issued a verification certificate, and it shall be noted that "this pressure gauge cannot be used as a standard for measurement transmission"; the pressure gauge that has been verified for the first time shall be noted as "first inspection, without verification of indication stability".
JJG875—2005
Verification cycle
The verification cycle can be determined according to the environmental conditions, frequency and working requirements of the pressure gauge, and generally does not exceed 1 year. For pressure gauges with unqualified indication stability, the verification cycle generally does not exceed half a year. 6
Appendix A
Inspection unit
Instrument information
Instrument name
Model and specification
Manufacturer
Factory number
Measuring range
Accuracy level
Appearance inspection
Insulation resistance
Indication difference:
Stability tolerance:
Verification conclusion:
Verification Staffing:
JJG875—2005
Digital pressure gauge calibration record format
Record No.
Environmental temperature:
Tested device
Zero drift
Periodic stability calibration
Indication error:
Stability:
Pressure gauge indication (
First calibration
Environmental humidity:||tt ||Standard instrument
Indication error verification
Second verification
Return error:
Static pressure zero position error:
Certificate number:
Daily inspector:
Return error:
Static pressure zero position error:
Appendix B
Appearance inspection:
Zero position drift:
Indication error:
Return error:| |tt||Static pressure zero error:
Stability:
Insulation resistance:
Verification data:
Indication of standard instrument
Note: Please bring the original certificate for the next verification.
JJG875-2005
Verification certificate (inner page) format
Verification results
Average value of pressure gauge positive stroke indication (
)Average value of pressure gauge reverse stroke indication (4 Before calibration, the calibration device or pressure gauge should be adjusted to make the pressure points of the two on the same horizontal plane as much as possible. When the pressure points of the two are not on the same horizontal plane, the additional calibration error caused by the height difference of the working medium should not be greater than one tenth of the maximum allowable error of the pressure gauge. Otherwise, additional error correction should be performed. The correction method is shown in Appendix D. 5.3.1.5 Selection of calibration points and number of calibration cycles. For pressure gauges with an accuracy level of 0.05 or above, the calibration points shall be no less than 10 points (including the zero point); for pressure gauges with an accuracy level of 0.1 or below, the calibration points shall be no less than 5 points (including the zero point). The selected calibration points shall be evenly distributed within the full range; for pressure gauges with an accuracy level of 0.05 or above, the number of calibration cycles for pressure increase and pressure reduction (or evacuation and pressure increase) shall be two; for pressure gauges with an accuracy level of 0.1 or below, the number of calibration cycles shall be one.
5.3.1.6 Before the indication calibration, one or two pressure increase (or evacuation) tests shall be performed. During the verification, the pressure increase (or evacuation) and pressure reduction (or pressure increase) should be smooth to avoid shock and overpressure. At each verification point, the pressure value should be stabilized before reading, and records should be kept.
5.3.2 Appearance inspection
The requirements of 4.1.1 to 4.1.4 should be checked by visual observation, and the requirements of 4.1.5 should be checked by power-on.
5.3.3 Insulation resistance verification
Disconnect the power supply, turn on the power switch of the pressure gauge, and use an insulation resistance meter to measure the insulation resistance between the power terminal and the casing.
Note: For pressure gauges powered by AC power, use an insulation resistance meter with a DC output of 500V; for pressure gauges powered by DC power, use an insulation resistance meter with a DC output of 100V. 5.3.4 Zero drift
After power-on preheating, under atmospheric pressure, if the pressure gauge has a zero adjustment device, the initial value can be adjusted to zero, and the displayed value can be recorded every 15 minutes until 1 hour. Among the differences between each displayed value and the initial displayed value, the value with the largest absolute value is the zero drift error.
5.3.5 Stability
After power-on preheating, without any adjustment (if there is a zero adjustment device, the initial value can be adjusted to zero), the pressure gauge should be calibrated for one cycle of forward and reverse strokes, and records should be made. The forward and reverse stroke indication error △pw of each calibration point should be calculated according to formula (1). The absolute value of the difference between the indication error △pw and the indication error Ap of the corresponding positive and negative strokes of each calibration point on the calibration certificate of the previous cycle is the indication stability between two adjacent calibration cycles, which is calculated according to formula (2): △pw=PD-Ps
AW=1pw-Apl
Wherein: Apw is the difference between the indication of each calibration point of the pressure gauge and the standard value, Pa, kPa or MPa; PD
is the indication of the positive and negative strokes of each calibration point of the pressure gauge, Pa, kPa or MPa; (1)
JJG875—2005
p,——the standard indication of each calibration point of the standard instrument, Pa, kPa or MPa; △W is the indication stability of the pressure gauge between two adjacent calibration cycles, Pa, kPa or MPa; Ap is the difference between the indication of the positive and negative strokes of each calibration point on the calibration certificate of the previous cycle and the standard value, Pa, kPa or MPa.
5.3.6 Indication error
5.3.6.1 Verification of indication error
a) After the periodic indication stability verification, if the pressure gauge indication is found to be out of tolerance, increase the pressure (or evacuate) to the full scale of the pressure gauge and compare it with the standard pressure value. Adjust the pressure gauge indication to the optimal value through the manual or automatic adjustment mechanism of the pressure gauge, and then conduct the indication error verification; if the pressure gauge indication is within the qualified range, the pressure gauge indication should also be adjusted to the optimal value, and then conduct the indication error verification (the pressure gauge of grade 0.1 and below can adjust the pressure gauge indication to the optimal value during pre-pressure.
b) Calculation of indication error. The indication error of the pressure gauge is calculated according to formula (3): Ap = PR-Ps
Where: △p——indication error of each calibration point of the pressure gauge, Pa, kPa or MPa; PR—indication of the positive and negative strokes of each calibration point of the pressure gauge, Pa, kPa or MPa; p. Standard indication of each calibration point of the standard instrument, Pa, kPa or MPa. 5.3.6.2 Verification of indication error of differential pressure gauge a) Verification of static pressure zero error
Connect the high pressure end (H) and low pressure end (L) of the one-way differential pressure gauge or the two-way differential pressure gauge, apply 100% of the rated static pressure, and read the static pressure zero indication after the pressure stabilizes. Perform three consecutive verifications. b) Verification of indication error of one-way differential pressure gauge The low pressure end (L) is connected to the atmosphere, and the high pressure end (H) is connected to the verification device. The indication error verification and indication error calculation are carried out according to 5.3.6.1.
c) Verification of indication error of bidirectional differential pressure gauge: First, let the low pressure end (L) pass to the atmosphere and connect the high pressure end (H) to the verification device; then let the high pressure end (H) pass to the atmosphere and connect the low pressure end (L) to the verification device. Verification of indication error and calculation of indication error shall be carried out in accordance with 5.3.6.1. 5.3.7 Verification of return error
The return error can be calculated using the data of the indication error verification. The absolute value of the difference between the forward and reverse stroke indications at the same verification point is taken as the return error of the pressure gauge. 5.3.8 Verification of additional functions
The verification of additional functions of the pressure gauge shall be carried out in accordance with the corresponding metrological verification procedures. 5.4 Handling of verification results
The pressure gauge that has been verified is qualified if its metrological performance and general technical requirements meet the requirements of this regulation, and a verification certificate (format see Appendix B); if one item does not meet the requirements of this regulation, it is unqualified, and a verification result notice (format see Appendix C) is issued, and the unqualified items and contents are noted; when the change in indication between two verification cycles is greater than the absolute value of the maximum allowable error, the pressure gauge that has passed the verification after debugging shall be issued a verification certificate, and it shall be noted that "this pressure gauge cannot be used as a standard for measurement transmission"; the pressure gauge that has been verified for the first time shall be noted as "first inspection, without verification of indication stability".
JJG875—2005
Verification cycle
The verification cycle can be determined according to the environmental conditions, frequency and working requirements of the pressure gauge, and generally does not exceed 1 year. For pressure gauges with unqualified indication stability, the verification cycle generally does not exceed half a year. 6
Appendix A
Inspection unit
Instrument information
Instrument name
Model and specification
Manufacturer
Factory number
Measuring range
Accuracy level
Appearance inspection
Insulation resistance
Indication difference:
Stability tolerance:
Verification conclusion:
Verification Staffing:
JJG875—2005
Digital pressure gauge calibration record format
Record No.
Environmental temperature:
Tested device
Zero drift
Periodic stability calibration
Indication error:
Stability:
Pressure gauge indication (
First calibration
Environmental humidity:||tt ||Standard instrument
Indication error verification
Second verification
Return error:
Static pressure zero position error:
Certificate number:
Daily inspector:
Return error:
Static pressure zero position error:
Appendix B
Appearance inspection:
Zero position drift:
Indication error:
Return error:| |tt||Static pressure zero error:
Stability:
Insulation resistance:
Verification data:
Indication of standard instrument
Note: Please bring the original certificate for the next verification.
JJG875-2005
Verification certificate (inner page) format
Verification results
Average value of pressure gauge positive stroke indication (
)Average value of pressure gauge reverse stroke indication (4 Before calibration, the calibration device or pressure gauge should be adjusted to make the pressure points of the two on the same horizontal plane as much as possible. When the pressure points of the two are not on the same horizontal plane, the additional calibration error caused by the height difference of the working medium should not be greater than one tenth of the maximum allowable error of the pressure gauge. Otherwise, additional error correction should be performed. The correction method is shown in Appendix D. 5.3.1.5 Selection of calibration points and number of calibration cycles. For pressure gauges with an accuracy level of 0.05 or above, the calibration points shall be no less than 10 points (including the zero point); for pressure gauges with an accuracy level of 0.1 or below, the calibration points shall be no less than 5 points (including the zero point). The selected calibration points shall be evenly distributed within the full range; for pressure gauges with an accuracy level of 0.05 or above, the number of calibration cycles for pressure increase and pressure reduction (or evacuation and pressure increase) shall be two; for pressure gauges with an accuracy level of 0.1 or below, the number of calibration cycles shall be one.
5.3.1.6 Before the indication calibration, one or two pressure increase (or evacuation) tests shall be performed. During the verification, the pressure increase (or evacuation) and pressure reduction (or pressure increase) should be smooth to avoid shock and overpressure. At each verification point, the pressure value should be stabilized before reading, and records should be kept.
5.3.2 Appearance inspection
The requirements of 4.1.1 to 4.1.4 should be checked by visual observation, and the requirements of 4.1.5 should be checked by power-on.
5.3.3 Insulation resistance verification
Disconnect the power supply, turn on the power switch of the pressure gauge, and use an insulation resistance meter to measure the insulation resistance between the power terminal and the casing.
Note: For pressure gauges powered by AC power, use an insulation resistance meter with a DC output of 500V; for pressure gauges powered by DC power, use an insulation resistance meter with a DC output of 100V. 5.3.4 Zero drift
After power-on preheating, under atmospheric pressure, if the pressure gauge has a zero adjustment device, the initial value can be adjusted to zero, and the displayed value can be recorded every 15 minutes until 1 hour. Among the differences between each displayed value and the initial displayed value, the value with the largest absolute value is the zero drift error.
5.3.5 Stability
After power-on preheating, without any adjustment (if there is a zero adjustment device, the initial value can be adjusted to zero), the pressure gauge should be calibrated for one cycle of forward and reverse strokes, and records should be made. The forward and reverse stroke indication error △pw of each calibration point should be calculated according to formula (1). The absolute value of the difference between the indication error △pw and the indication error Ap of the corresponding positive and negative strokes of each calibration point on the calibration certificate of the previous cycle is the indication stability between two adjacent calibration cycles, which is calculated according to formula (2): △pw=PD-Ps
AW=1pw-Apl
Wherein: Apw is the difference between the indication of each calibration point of the pressure gauge and the standard value, Pa, kPa or MPa; PD
is the indication of the positive and negative strokes of each calibration point of the pressure gauge, Pa, kPa or MPa; (1)
JJG875—2005
p,——the standard indication of each calibration point of the standard instrument, Pa, kPa or MPa; △W is the indication stability of the pressure gauge between two adjacent calibration cycles, Pa, kPa or MPa; Ap is the difference between the indication of the positive and negative strokes of each calibration point on the calibration certificate of the previous cycle and the standard value, Pa, kPa or MPa.
5.3.6 Indication error
5.3.6.1 Verification of indication error
a) After the periodic indication stability verification, if the pressure gauge indication is found to be out of tolerance, increase the pressure (or evacuate) to the full scale of the pressure gauge and compare it with the standard pressure value. Adjust the pressure gauge indication to the optimal value through the manual or automatic adjustment mechanism of the pressure gauge, and then conduct the indication error verification; if the pressure gauge indication is within the qualified range, the pressure gauge indication should also be adjusted to the optimal value, and then conduct the indication error verification (the pressure gauge of grade 0.1 and below can adjust the pressure gauge indication to the optimal value during pre-pressure.
b) Calculation of indication error. The indication error of the pressure gauge is calculated according to formula (3): Ap = PR-Ps
Where: △p——indication error of each calibration point of the pressure gauge, Pa, kPa or MPa; PR—indication of the positive and negative strokes of each calibration point of the pressure gauge, Pa, kPa or MPa; p. Standard indication of each calibration point of the standard instrument, Pa, kPa or MPa. 5.3.6.2 Verification of indication error of differential pressure gauge a) Verification of static pressure zero error
Connect the high pressure end (H) and low pressure end (L) of the one-way differential pressure gauge or the two-way differential pressure gauge, apply 100% of the rated static pressure, and read the static pressure zero indication after the pressure stabilizes. Perform three consecutive verifications. b) Verification of indication error of one-way differential pressure gauge The low pressure end (L) is connected to the atmosphere, and the high pressure end (H) is connected to the verification device. The indication error verification and indication error calculation are carried out according to 5.3.6.1.
c) Verification of indication error of bidirectional differential pressure gauge: First, let the low pressure end (L) pass to the atmosphere and connect the high pressure end (H) to the verification device; then let the high pressure end (H) pass to the atmosphere and connect the low pressure end (L) to the verification device. Verification of indication error and calculation of indication error shall be carried out in accordance with 5.3.6.1. 5.3.7 Verification of return error
The return error can be calculated using the data of the indication error verification. The absolute value of the difference between the forward and reverse stroke indications at the same verification point is taken as the return error of the pressure gauge. 5.3.8 Verification of additional functions
The verification of additional functions of the pressure gauge shall be carried out in accordance with the corresponding metrological verification procedures. 5.4 Handling of verification results
The pressure gauge that has been verified is qualified if its metrological performance and general technical requirements meet the requirements of this regulation, and a verification certificate (format see Appendix B); if one item does not meet the requirements of this regulation, it is unqualified, and a verification result notice (format see Appendix C) is issued, and the unqualified items and contents are noted; when the change in indication between two verification cycles is greater than the absolute value of the maximum allowable error, the pressure gauge that has passed the verification after debugging shall be issued a verification certificate, and it shall be noted that "this pressure gauge cannot be used as a standard for measurement transmission"; the pressure gauge that has been verified for the first time shall be noted as "first inspection, without verification of indication stability".
JJG875—2005
Verification cycle
The verification cycle can be determined according to the environmental conditions, frequency and working requirements of the pressure gauge, and generally does not exceed 1 year. For pressure gauges with unqualified indication stability, the verification cycle generally does not exceed half a year. 6
Appendix A
Inspection unit
Instrument information
Instrument name
Model and specification
Manufacturer
Factory number
Measuring range
Accuracy level
Appearance inspection
Insulation resistance
Indication difference:
Stability tolerance:
Verification conclusion:
Verification Staffing:
JJG875—2005
Digital pressure gauge calibration record format
Record No.
Environmental temperature:
Tested device
Zero drift
Periodic stability calibration
Indication error:
Stability:
Pressure gauge indication (
First calibration
Environmental humidity:||tt ||Standard instrument
Indication error verification
Second verification
Return error:
Static pressure zero position error:
Certificate number:
Daily inspector:
Return error:
Static pressure zero position error:
Appendix B
Appearance inspection:
Zero position drift:
Indication error:
Return error:| |tt||Static pressure zero error:
Stability:
Insulation resistance:
Verification data:
Indication of standard instrument
Note: Please bring the original certificate for the next verification.
JJG875-2005
Verification certificate (inner page) format
Verification results
Average value of pressure gauge positive stroke indication (
)Average value of pressure gauge reverse stroke indication (The calibration points of pressure gauges of level 1 and below shall be no less than 5 points (including zero 3
pressure standard
JJG875—2005
connecting pipeline
three-way joint
pressure generator
Figure 2 Diagram of calibration connection of pressure gauge indication error pressure gauge to be tested
points), and the selected calibration points shall be evenly distributed within the full range; for pressure gauges of accuracy level 0.05 and above, the number of calibration cycles of pressure increase and pressure reduction (or evacuation and pressure increase) shall be two; the number of calibration cycles of pressure gauges of level 0.1 and below shall be one.
5.3.1.6 Before the indication calibration, 1~2 pressure increase (or evacuation) tests shall be performed. During the calibration, the pressure increase (or evacuation) and pressure reduction (or pressure increase) shall be stable to avoid shock and overpressure. At each calibration point, the pressure value should be stabilized before reading, and records should be made.
5.3.2 Appearance inspection
The requirements of 4.1.1 to 4.1.4 shall be inspected by visual inspection, and the requirements of 4.1.5 shall be inspected by power-on.
5.3.3 Insulation resistance inspection
Disconnect the power supply, turn on the power switch of the pressure gauge, and use an insulation resistance meter to measure the insulation resistance between the power supply terminal and the housing.
Note: For pressure gauges powered by AC power, an insulation resistance meter with a DC output of 500V is used; for pressure gauges powered by DC power, an insulation resistance meter with a DC output of 100V is used. 5.3.4 Zero drift
After power-on preheating, under atmospheric pressure, the pressure gauge with a zero adjustment device can adjust the initial value to zero, and record the displayed value every 15 minutes until 1 hour. Among the differences between each displayed value and the initial displayed value, the value with the largest absolute value is the zero drift error.
5.3.5 Stability
After power-on preheating, the pressure gauge should be calibrated for one cycle of forward and reverse stroke without any adjustment (the initial value can be adjusted to zero if there is a zero adjustment device), and records should be made. The forward and reverse stroke indication error △pw of each calibration point should be calculated according to formula (1). The absolute value of the difference between the indication error △pw and the indication error Ap of the corresponding positive and negative strokes of each calibration point on the calibration certificate of the previous cycle is the indication stability between two adjacent calibration cycles, which is calculated according to formula (2): △pw=PD-Ps
AW=1pw-Apl
Wherein: Apw is the difference between the indication of each calibration point of the pressure gauge and the standard value, Pa, kPa or MPa; PD
is the indication of the positive and negative strokes of each calibration point of the pressure gauge, Pa, kPa or MPa; (1)
JJG875—2005
p,——the standard indication of each calibration point of the standard instrument, Pa, kPa or MPa; △W is the indication stability of the pressure gauge between two adjacent calibration cycles, Pa, kPa or MPa; Ap is the difference between the indication of the positive and negative strokes of each calibration point on the calibration certificate of the previous cycle and the standard value, Pa, kPa or MPa.
5.3.6 Indication error
5.3.6.1 Verification of indication error
a) After the periodic indication stability verification, if the pressure gauge indication is found to be out of tolerance, increase the pressure (or evacuate) to the full scale of the pressure gauge and compare it with the standard pressure value. Adjust the pressure gauge indication to the optimal value through the manual or automatic adjustment mechanism of the pressure gauge, and then conduct the indication error verification; if the pressure gauge indication is within the qualified range, the pressure gauge indication should also be adjusted to the optimal value, and then conduct the indication error verification (the pressure gauge of grade 0.1 and below can adjust the pressure gauge indication to the optimal value during pre-pressure.
b) Calculation of indication error. The indication error of the pressure gauge is calculated according to formula (3): Ap = PR-Ps
Where: △p——indication error of each calibration point of the pressure gauge, Pa, kPa or MPa; PR—indication of the positive and negative strokes of each calibration point of the pressure gauge, Pa, kPa or MPa; p. Standard indication of each calibration point of the standard instrument, Pa, kPa or MPa. 5.3.6.2 Verification of indication error of differential pressure gauge a) Verification of static pressure zero error
Connect the high pressure end (H) and low pressure end (L) of the one-way differential pressure gauge or the two-way differential pressure gauge, apply 100% of the rated static pressure, and read the static pressure zero indication after the pressure stabilizes. Perform three consecutive verifications. b) Verification of indication error of one-way differential pressure gauge The low pressure end (L) is connected to the atmosphere, and the high pressure end (H) is connected to the verification device. The indication error verification and indication error calculation are carried out according to 5.3.6.1.
c) Verification of indication error of bidirectional differential pressure gauge: First, let the low pressure end (L) pass to the atmosphere and connect the high pressure end (H) to the verification device; then let the high pressure end (H) pass to the atmosphere and connect the low pressure end (L) to the verification device. Verification of indication error and calculation of indication error shall be carried out in accordance with 5.3.6.1. 5.3.7 Verification of return error
The return error can be calculated using the data of the indication error verification. The absolute value of the difference between the forward and reverse stroke indications at the same verification point is taken as the return error of the pressure gauge. 5.3.8 Verification of additional functions
The verification of additional functions of the pressure gauge shall be carried out in accordance with the corresponding metrological verification procedures. 5.4 Handling of verification results
The pressure gauge that has been verified is qualified if its metrological performance and general technical requirements meet the requirements of this regulation, and a verification certificate (format see Appendix B); if one item does not meet the requirements of this regulation, it is unqualified, and a verification result notice (format see Appendix C) is issued, and the unqualified items and contents are noted; when the change in indication between two verification cycles is greater than the absolute value of the maximum allowable error, the pressure gauge that has passed the verification after debugging shall be issued a verification certificate, and it shall be noted that "this pressure gauge cannot be used as a standard for measurement transmission"; the pressure gauge that has been verified for the first time shall be noted as "first inspection, without verification of indication stability".
JJG875—2005
Verification cycle
The verification cycle can be determined according to the environmental conditions, frequency and working requirements of the pressure gauge, and generally does not exceed 1 year. For pressure gauges with unqualified indication stability, the verification cycle generally does not exceed half a year. 6
Appendix A
Inspection unit
Instrument information
Instrument name
Model and specification
Manufacturer
Factory number
Measuring range
Accuracy level
Appearance inspection
Insulation resistance
Indication difference:
Stability tolerance:
Verification conclusion:
Verification Staffing:
JJG875—2005
Digital pressure gauge calibration record format
Record No.
Environmental temperature:
Tested device
Zero drift
Periodic stability calibration
Indication error:
Stability:
Pressure gauge indication (
First calibration
Environmental humidity:||tt ||Standard instrument
Indication error verification
Second verification
Return error:
Static pressure zero position error:
Certificate number:
Daily inspector:
Return error:
Static pressure zero position error:
Appendix B
Appearance inspection:
Zero position drift:
Indication error:
Return error:| |tt||Static pressure zero error:
Stability:
Insulation resistance:
Verification data:
Indication of standard instrument
Note: Please bring the original certificate for the next verification.
JJG875-2005bZxz.net
Verification certificate (inner page) format
Verification results
Average value of pressure gauge positive stroke indication (
)Average value of pressure gauge reverse stroke indication (The calibration points of pressure gauges of level 1 and below shall be no less than 5 points (including zero 3
pressure standard
JJG875—2005
connecting pipeline
three-way joint
pressure generator
Figure 2 Diagram of calibration connection of pressure gauge indication error pressure gauge to be tested
points), and the selected calibration points shall be evenly distributed within the full range; for pressure gauges of accuracy level 0.05 and above, the number of calibration cycles of pressure increase and pressure reduction (or evacuation and pressure increase) shall be two; the number of calibration cycles of pressure gauges of level 0.1 and below shall be one.
5.3.1.6 Before the indication calibration, 1~2 pressure increase (or evacuation) tests shall be performed. During the calibration, the pressure increase (or evacuation) and pressure reduction (or pressure increase) shall be stable to avoid shock and overpressure. At each calibration point, the pressure value should be stabilized before reading, and records should be made.
5.3.2 Appearance inspection
The requirements of 4.1.1 to 4.1.4 shall be inspected by visual inspection, and the requirements of 4.1.5 shall be inspected by power-on.
5.3.3 Insulation resistance inspection
Disconnect the power supply, turn on the power switch of the pressure gauge, and use an insulation resistance meter to measure the insulation resistance between the power supply terminal and the housing.
Note: For pressure gauges powered by AC power, an insulation resistance meter with a DC output of 500V is used; for pressure gauges powered by DC power, an insulation resistance meter with a DC output of 100V is used. 5.3.4 Zero drift
After power-on preheating, under atmospheric pressure, the pressure gauge with a zero adjustment device can adjust the initial value to zero, and record the displayed value every 15 minutes until 1 hour. Among the differences between each displayed value and the initial displayed value, the value with the largest absolute value is the zero drift error.
5.3.5 Stability
After power-on preheating, the pressure gauge should be calibrated for one cycle of forward and reverse stroke without any adjustment (the initial value can be adjusted to zero if there is a zero adjustment device), and records should be made. The forward and reverse stroke indication error △pw of each calibration point should be calculated according to formula (1). The absolute value of the difference between the indication error △pw and the indication error Ap of the corresponding positive and negative strokes of each calibration point on the calibration certificate of the previous cycle is the indication stability between two adjacent calibration cycles, which is calculated according to formula (2): △pw=PD-Ps
AW=1pw-Apl
Wherein: Apw is the difference between the indication of each calibration point of the pressure gauge and the standard value, Pa, kPa or MPa; PD
is the indication of the positive and negative strokes of each calibration point of the pressure gauge, Pa, kPa or MPa; (1)
JJG875—2005
p,——the standard indication of each calibration point of the standard instrument, Pa, kPa or MPa; △W is the indication stability of the pressure gauge between two adjacent calibration cycles, Pa, kPa or MPa; Ap is the difference between the indication of the positive and negative strokes of each calibration point on the calibration certificate of the previous cycle and the standard value, Pa, kPa or MPa.
5.3.6 Indication error
5.3.6.1 Verification of indication error
a) After the periodic indication stability verification, if the pressure gauge indication is found to be out of tolerance, increase the pressure (or evacuate) to the full scale of the pressure gauge and compare it with the standard pressure value. Adjust the pressure gauge indication to the optimal value through the manual or automatic adjustment mechanism of the pressure gauge, and then conduct the indication error verification; if the pressure gauge indication is within the qualified range, the pressure gauge indication should also be adjusted to the optimal value, and then conduct the indication error verification (the pressure gauge of grade 0.1 and below can adjust the pressure gauge indication to the optimal value during pre-pressure.
b) Calculation of indication error. The indication error of the pressure gauge is calculated according to formula (3): Ap = PR-Ps
Where: △p——indication error of each calibration point of the pressure gauge, Pa, kPa or MPa; PR—indication of the positive and negative strokes of each calibration point of the pressure gauge, Pa, kPa or MPa; p. Standard indication of each calibration point of the standard instrument, Pa, kPa or MPa. 5.3.6.2 Verification of indication error of differential pressure gauge a) Verification of static pressure zero error
Connect the high pressure end (H) and low pressure end (L) of the one-way differential pressure gauge or the two-way differential pressure gauge, apply 100% of the rated static pressure, and read the static pressure zero indication after the pressure stabilizes. Perform three consecutive verifications. b) Verification of indication error of one-way differential pressure gauge The low pressure end (L) is connected to the atmosphere, and the high pressure end (H) is connected to the verification device. The indication error verification and indication error calculation are carried out according to 5.3.6.1.
c) Verification of indication error of bidirectional differential pressure gauge: First, let the low pressure end (L) pass to the atmosphere and connect the high pressure end (H) to the verification device; then let the high pressure end (H) pass to the atmosphere and connect the low pressure end (L) to the verification device. Verification of indication error and calculation of indication error shall be carried out in accordance with 5.3.6.1. 5.3.7 Verification of return error
The return error can be calculated using the data of the indication error verification. The absolute value of the difference between the forward and reverse stroke indications at the same verification point is taken as the return error of the pressure gauge. 5.3.8 Verification of additional functions
The verification of additional functions of the pressure gauge shall be carried out in accordance with the corresponding metrological verification procedures. 5.4 Handling of verification results
The pressure gauge that has been verified is qualified if its metrological performance and general technical requirements meet the requirements of this regulation, and a verification certificate (format see Appendix B); if one item does not meet the requirements of this regulation, it is unqualified, and a verification result notice (format see Appendix C) is issued, and the unqualified items and contents are noted; when the change in indication between two verification cycles is greater than the absolute value of the maximum allowable error, the pressure gauge that has passed the verification after debugging shall be issued a verification certificate, and it shall be noted that "this pressure gauge cannot be used as a standard for measurement transmission"; the pressure gauge that has been verified for the first time shall be noted as "first inspection, without verification of indication stability".
JJG875—2005
Verification cycle
The verification cycle can be determined according to the environmental conditions, frequency and working requirements of the pressure gauge, and generally does not exceed 1 year. For pressure gauges with unqualified indication stability, the verification cycle generally does not exceed half a year. 6
Appendix A
Inspection unit
Instrument information
Instrument name
Model and specification
Manufacturer
Factory number
Measuring range
Accuracy level
Appearance inspection
Insulation resistance
Indication difference:
Stability tolerance:
Verification conclusion:
Verification Staffing:
JJG875—2005
Digital pressure gauge calibration record format
Record No.
Environmental temperature:
Tested device
Zero drift
Periodic stability calibration
Indication error:
Stability:
Pressure gauge indication (
First calibration
Environmental humidity:||tt ||Standard instrument
Indication error verification
Second verification
Return error:
Static pressure zero position error:
Certificate number:
Daily inspector:
Return error:
Static pressure zero position error:
Appendix B
Appearance inspection:
Zero position drift:
Indication error:
Return error:| |tt||Static pressure zero error:
Stability:
Insulation resistance:
Verification data:
Indication of standard instrument
Note: Please bring the original certificate for the next verification.
JJG875-2005
Verification certificate (inner page) format
Verification results
Average value of pressure gauge positive stroke indication (
)Average value of pressure gauge reverse stroke indication (3 Insulation resistance verification
Disconnect the power supply, turn on the power switch of the pressure gauge, and use an insulation resistance meter to measure the insulation resistance between the power supply terminal and the housing.
Note: For pressure gauges powered by AC power, use an insulation resistance meter with a DC output of 500V; for pressure gauges powered by DC power, use an insulation resistance meter with a DC output of 100V. 5.3.4 Zero drift
After power-on preheating, under atmospheric pressure, the pressure gauge with a zero adjustment device can adjust the initial value to zero, and record the displayed value every 15 minutes until 1 hour. Among the differences between each displayed value and the initial displayed value, the value with the largest absolute value is the zero drift error.
5.3.5 Stability
After power-on preheating, the pressure gauge should be verified for one cycle of forward and reverse stroke without any adjustment (if there is a zero adjustment device, the initial value can be adjusted to zero), and records should be made. The forward and reverse stroke indication error △pw of each verification point should be calculated according to formula (1). The absolute value of the difference between the indication error △pw and the indication error Ap of the corresponding positive and negative strokes of each calibration point on the calibration certificate of the previous cycle is the indication stability between two adjacent calibration cycles, which is calculated according to formula (2): △pw=PD-Ps
AW=1pw-Apl
Wherein: Apw is the difference between the indication of each calibration point of the pressure gauge and the standard value, Pa, kPa or MPa; PD
is the indication of the positive and negative strokes of each calibration point of the pressure gauge, Pa, kPa or MPa; (1)
JJG875—2005
p,——the standard indication of each calibration point of the standard instrument, Pa, kPa or MPa; △W is the indication stability of the pressure gauge between two adjacent calibration cycles, Pa, kPa or MPa; Ap is the difference between the indication of the positive and negative strokes of each calibration point on the calibration certificate of the previous cycle and the standard value, Pa, kPa or MPa.
5.3.6 Indication error
5.3.6.1 Verification of indication error
a) After the periodic indication stability verification, if the pressure gauge indication is found to be out of tolerance, increase the pressure (or evacuate) to the full scale of the pressure gauge and compare it with the standard pressure value. Adjust the pressure gauge indication to the optimal value through the manual or automatic adjustment mechanism of the pressure gauge, and then conduct the indication error verification; if the pressure gauge indication is within the qualified range, the pressure gauge indication should also be adjusted to the optimal value, and then conduct the indication error verification (the pressure gauge of grade 0.1 and below can adjust the pressure gauge indication to the optimal value during pre-pressure.
b) Calculation of indication error. The indication error of the pressure gauge is calculated according to formula (3): Ap = PR-Ps
Where: △p——indication error of each calibration point of the pressure gauge, Pa, kPa or MPa; PR—indication of the positive and negative strokes of each calibration point of the pressure gauge, Pa, kPa or MPa; p. Standard indication of each calibration point of the standard instrument, Pa, kPa or MPa. 5.3.6.2 Verification of indication error of differential pressure gauge a) Verification of static pressure zero error
Connect the high pressure end (H) and low pressure end (L) of the one-way differential pressure gauge or the two-way differential pressure gauge, apply 100% of the rated static pressure, and read the static pressure zero indication after the pressure stabilizes. Perform three consecutive verifications. b) Verification of indication error of one-way differential pressure gauge The low pressure end (L) is connected to the atmosphere, and the high pressure end (H) is connected to the verification device. The indication error verification and indication error calculation are carried out according to 5.3.6.1.
c) Verification of indication error of bidirectional differential pressure gauge: First, let the low pressure end (L) pass to the atmosphere and connect the high pressure end (H) to the verification device; then let the high pressure end (H) pass to the atmosphere and connect the low pressure end (L) to the verification device. Verification of indication error and calculation of indication error shall be carried out in accordance with 5.3.6.1. 5.3.7 Verification of return error
The return error can be calculated using the data of the indication error verification. The absolute value of the difference between the forward and reverse stroke indications at the same verification point is taken as the return error of the pressure gauge. 5.3.8 Verification of additional functions
The verification of additional functions of the pressure gauge shall be carried out in accordance with the corresponding metrological verification procedures. 5.4 Handling of verification results
The pressure gauge that has been verified is qualified if its metrological performance and general technical requirements meet the requirements of this regulation, and a verification certificate (format see Appendix B); if one item does not meet the requirements of this regulation, it is unqualified, and a verification result notice (format see Appendix C) is issued, and the unqualified items and contents are noted; when the change in indication between two verification cycles is greater than the absolute value of the maximum allowable error, the pressure gauge that has passed the verification after debugging shall be issued a verification certificate, and it shall be noted that "this pressure gauge cannot be used as a standard for measurement transmission"; the pressure gauge that has been verified for the first time shall be noted as "first inspection, without verification of indication stability".
JJG875—2005
Verification cycle
The verification cycle can be determined according to the environmental conditions, frequency and working requirements of the pressure gauge, and generally does not exceed 1 year. For pressure gauges with unqualified indication stability, the verification cycle generally does not exceed half a year. 6
Appendix A
Inspection unit
Instrument information
Instrument name
Model and specification
Manufacturer
Factory number
Measuring range
Accuracy level
Appearance inspection
Insulation resistance
Indication difference:
Stability tolerance:
Verification conclusion:
Verification Staffing:
JJG875—2005
Digital pressure gauge calibration record format
Record No.
Environmental temperature:
Tested device
Zero drift
Periodic stability calibration
Indication error:
Stability:
Pressure gauge indication (
First calibration
Environmental humidity:||tt ||Standard instrument
Indication error verification
Second verification
Return error:
Static pressure zero position error:
Certificate number:
Daily
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