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)
1范圍
本規程適用于壓力(包括正、負表壓力，差壓和絕對壓力)變送器的定型鑒定(或樣機試驗)、首次檢定、后續檢定和使用中檢驗。
2 引用文獻
本規程引用下列文獻：
JJF 1015—2002計量器具型式評價和型式批準通用規范
JJF 1016—2002計量器具型式評價大綱編寫導則
JJG 875—1994數字壓力計檢定規程
GB/T 17614.1—1998工業過程控制系統用變送器 第1部分：性能評定方法
GB/T 17626.3—1998射頻電磁場輻射抗擾度試驗
使用本規程時，應注意使用上述引用文獻的現行有效版本。
3概述
壓力變送器是一種將壓力變量轉換為可傳送的標準化輸出信號的儀表，而且其輸出信號與壓力變量之間有一給定的連續函數關系(通常為線性函數)。主要用于工業過程壓力參數的測量和控制，差壓變送器常用于流量的測量。
壓力變送器有電動和氣動兩大類。電動的標準化輸出信號主要為0mA～10mA和4mA～20mA(或1V～5V)的直流電信號。氣動的標準化輸出信號主要為20kPa～100kPa的氣體壓力。不排除具有特殊規定的其他標準化輸出信號。
壓力變送器通常由兩部分組成：感壓單元、信號處理和轉換單元。有些變送器增加了顯示單元，有些還具有現場總線功能。壓力變送器的結構原理如圖1所示。
壓力變送器按原理可分為電容式、諧振式、壓阻式、力(力矩)平衡式、電感式和應變式等。
壓力(或差壓)信號
感壓單元
顯示單元
信號處理
和轉換單元
現場總線
輸出信號(mA、V或kPa)
圖1壓力變送器原理框圖
4計量性能要求
4.1測量誤差
壓力變送器的測量誤差按準確度等級劃分，應不超過表1規定。
表1準確度等級及最大允許誤差、回差
準確度等級 最大允許誤差/％ 回差/％
電動 氣動 電動 氣動
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
注：最大允許誤差和回差是以輸出量程的百分數表示。
4.2 回差
首次檢定的壓力變送器，其回差應不超過表1規定。后續檢定和使用中檢驗的壓力變送器，其回差應不超過最大允許誤差的絕對值。
4.3靜壓影響
靜壓影響只適用于差壓變送器。并以輸出下限值和量程的變化來衡量。
4.3.1力平衡式差壓變送器的靜壓影響應不超過表2規定。
表2 力平衡式差壓變送器靜壓影響要求
項目 準確度等級
0.5 1.0 1.5 2.0
指標(輸出量程的％)
下限值
及量程
變化 pW≤6.4 2.0 2.5 3.0 3.0
pW≤6.4(差壓量程≤6kPa) 3.0 3.5 4.0 —
6.4
JJG 882-2004 引用如下標準： |
JJG 882-2004被如下標準引用：
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