Verification Regulation of the Pressure Transmitter
1 Scope
This Regulation is applicable to type appraisal (or prototype test), initial verification, subsequent verification and in-service inspection of pressure transmitter (including positive/negative gauge pressure, differential pressure and absolute pressure).
2 References
The following documents are referenced in this Regulation:
JJF 1015-2002 General Norm for Pattern Evaluation and Pattern Approval of Measuring Instruments
JJF 1016-2002 The Rules for Drafting Program of Pattern Evaluation of Measuring Instruments
JJG 875-1994 Verification Regulation of Digital Pressure Gauges
GB/T 17614.1-1998 Transmitters for Use in Industrial-Process Control Systems—Part 1: Methods for Performance Evaluation
GB/T 17626.3-1998 Electromagnetic Compatibility—Testing and Measurement Techniques—Radiated Radio-Frequency Electromagnetic Field Immunity Test
While applying this Regulation, attention shall be paid to that the currently valid versions of the above references are applied.
3 General
The pressure transmitter refers to an instrument which converts the pressure variables into standardized transmissible output signals; where, both show a continuous function relationship as specified (linear function in general). It is mainly used for measurement and control of pressure parameters in industrial process; differential pressure transmitter is generally used for flow measurement.
Pressure transmitter is classified into electric and pneumatic ones. For electric type, the standardized output signal is mainly DC signal of 0mA~10mA and 4mA~20mA (or 1V~5V). For pneumatic type, the standardized output signal is mainly gas pressure of 20kPa~100kPa. Other standardized output signals of special requirements may be available.
Pressure transmitter generally consists of pressure sensing unit, signal processing and conversion unit. Some transmitters are additionally installed with display unit or with fieldbus function. The structure principle of pressure transmitter is shown in Figure 1.
Pressure transmitter may be classified into capacitive, resonant, piezoresistive, force/moment-balance, inductive and strain ones by principle.
Figure 1 Functional Block Diagram of Pressure Transmitter
4 Metrological Performance Requirements
4.1 Measurement Error
The measurement error of pressure transmitter is classified according to accuracy grade and shall not exceed those specified in Table 1.
Table 1 Accuracy Grade, Maximum Permissible Error and Return Difference
Accuracy grade Maximum permissible error/% Return difference/%
Electric Pneumatic Electric Pneumatic
0.05 ±0.05 — 0.05 —
0.1 ±0.1 — 0.08 —
0.2(0.25) ±0.2(±0.25) — 0.16(0.20) —
0.5 ±0.5 ±0.5 0.4 0.25
1.0 ±1.0 ±1.0 0.8 0.5
1.5 ±1.5 ±1.0 1.2 0.75
2.0 ±2.0 ±2.0 1.6 1.0
2.5 — ±2.5 — 1.25
Note: The maximum permissible error and return difference are expressed by the percentage of output range.
4.2 Return Difference
For pressure transmitter subject to initial verification, the return difference shall not exceed those specified in Table 1. For pressure transmitter subject to subsequent verification and in-service inspection, the return difference shall not exceed the absolute value of maximum permissible error.
4.3 Influence of Static Pressure
The influence of static pressure is only applicable to differential pressure transmitter and is measured according to the lower limit of output and changes of range.
4.3.1 The influence of static pressure of force-balance differential pressure transmitter shall not exceed those specified in Table 2.
Table 2 Requirements for Influence of Static Pressure of
Force-balance Differential Pressure Transmitter
Item Accuracy grade
0.5 1.0 1.5 2.0
Index (percentage of output range)
Lower limit and range change pW≤6.4 2.0 2.5 3.0 3.0
pW≤6.4 (Range of differential pressure ≤6kPa) 3.0 3.5 4.0 —
6.4
Foreword i
1 Scope
2 References
3 General
4 Metrological Performance Requirements
4.1 Measurement Error
4.2 Return Difference
4.3 Influence of Static Pressure
5 General Technical Requirements
5.1 Appearance
5.2 Leak Tightness
5.3 Insulation Resistance
5.4 Insulation Strength
6 Control of Measuring Instrument
6.1 Type Appraisal (or Prototype Test)
6.2 Initial Verification, Subsequent Verification and In-service Inspection
Annex A Equipment Connection Mode during Verification of Pressure Transmitter
Annex B Test Items and Method of Type Appraisal (or Prototype Test)
Annex C Verification Record Format of Pressure Transmitter
Annex D Uncertainty Analysis Examples
Annex E Format of Verification Certificate and Result Notification (Inside Pages)
