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范围
本规程适用于压力(包括正、负表压力，差压和绝对压力)变送器的定型鉴定(或样机试验)、首次检定、后续检定和使用中检验。
2 引用文献
本规程引用下列文献：
JJF 1015—2002计量器具型式评价和型式批准通用规范
JJF 1016—2002计量器具型式评价大纲编写导则
JJG 875—1994数字压力计检定规程
GB/T 17614.1—1998工业过程控制系统用变送器 第1部分：性能评定方法
GB/T 17626.3—1998射频电磁场辐射抗扰度试验
使用本规程时，应注意使用上述引用文献的现行有效版本。
3概述
压力变送器是一种将压力变量转换为可传送的标准化输出信号的仪表，而且其输出信号与压力变量之间有一给定的连续函数关系(通常为线性函数)。主要用于工业过程压力参数的测量和控制，差压变送器常用于流量的测量。
压力变送器有电动和气动两大类。电动的标准化输出信号主要为0mA～10mA和4mA～20mA(或1V～5V)的直流电信号。气动的标准化输出信号主要为20kPa～100kPa的气体压力。不排除具有特殊规定的其他标准化输出信号。
压力变送器通常由两部分组成：感压单元、信号处理和转换单元。有些变送器增加了显示单元，有些还具有现场总线功能。压力变送器的结构原理如图1所示。
压力变送器按原理可分为电容式、谐振式、压阻式、力(力矩)平衡式、电感式和应变式等。
压力(或差压)信号
感压单元
显示单元
信号处理
和转换单元
现场总线
输出信号(mA、V或kPa)
图1压力变送器原理框图
4计量性能要求
4.1测量误差
压力变送器的测量误差按准确度等级划分，应不超过表1规定。
表1准确度等级及最大允许误差、回差
准确度等级 最大允许误差/％ 回差/％
电动 气动 电动 气动
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：最大允许误差和回差是以输出量程的百分数表示。
4.2 回差
首次检定的压力变送器，其回差应不超过表1规定。后续检定和使用中检验的压力变送器，其回差应不超过最大允许误差的绝对值。
4.3静压影响
静压影响只适用于差压变送器。并以输出下限值和量程的变化来衡量。
4.3.1力平衡式差压变送器的静压影响应不超过表2规定。
表2 力平衡式差压变送器静压影响要求
项目 准确度等级
0.5 1.0 1.5 2.0
指标(输出量程的％)
下限值
及量程
变化 pW≤6.4 2.0 2.5 3.0 3.0
pW≤6.4(差压量程≤6kPa) 3.0 3.5 4.0 —
6.4
JJG 882-2004 引用如下标准： |
JJG 882-2004被如下标准引用：
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