GB/T 42567.2-2023 in English

《GB/T 42567.2-2023工业过程测量变送器试验的参比条件和程序 第2部分：压力变送器的特定程序》由TC124（全国工业过程测量控制和自动化标准化技术委员会）归口，TC124SC2（全国工业过程测量控制和自动化标准化技术委员会控制仪表及装置、工业控制计算机系统分会）执行，主管部门为中国机械工业联合会。

GB/T 42567.2-2023 Reference conditions and procedures for testing industrial and process measurement transmitters - Part 2: Specific procedures for pressure transmitters

1 Scope

This document establishes specific procedures for testing pressure process measurement transmitters (PMT) used in measuring and control systems for industrial processes and for machinery control systems.

A pressure PMT can feature a remote seal to bring the process variable to the sensing element in the PMT. When the remote seal cannot be separated from the PMT, the complete device shall be tested.

For general test procedures, reference is made to GB/ T 42567.1-2023, which is applicable to all types of process measurement transmitters.

Note: In industrial and process applications, to indicate the process measurement transmitters, it is common also to use the terms "industrial transmitters", or "process transmitters".

2 Normative references

The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

GB/T 42567.1-2023 Reference conditions and procedures for testing industrial and process measurement transmitters - Part 1 : General procedures for all types of transmitters (IEC 62828-1 : 2017, IDT)
IEC 62828-1 Reference conditions and procedures for testing industrial and process measurement transmitters - Part 1 : General procedures for all types of transmitters

3 Terms and definitions

For the purposes of this document, the terms and definitions given in IEC 62828-1 and the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

- IEC Electropedia : available at http://www.electropedia.org/

- ISO Online browsing platform: available at http://www.iso.org/obp

3.1 General

3.1.1
absolute pressure
pabs
pressure using absolute vacuum as the datum point

Note: The CDD code of this entry for Electronic Data Exchange is ABB181.

3.1.2
ambient atmospheric pressure
pamb
pressure exerted by the atmospheric air at a given altitude and temperature

Note: The atmospheric pressure decreases with the altitude by about 10 Pa/m (Pascal per metre).

3.1.3
differential pressure
△p
p1, 2
difference between the two (absolute) pressures that act simultaneously on opposite sides of a membrane or a primary element

Note: The CDD code of this entry for Electronic Data Exchange is ABB995.

3.1.4
gauge pressure
pg
pressure using atmospheric pressure as the datum point

Note 1: Gauge pressure assumes positive values when the absolute pressure is greater than the ambient atmospheric pressure; it assumes negative values when the absolute pressure is less than the ambient atmospheric pressure.

Note 2: In certain industrial environments, "gauge pressure" may be referred to as "pressure".

Note 3: The term "relative pressure" to indicate gauge pressure is obsolete and conceptually wrong, so it should be avoided.

Note 4: The CDD code of this entry for Electronic Data Exchange is ABB182.

3.1.5
line pressure
static pressure
pressure applied on both sides of a differential pressure PMT

Note: For differential pressure PMTs, it is an influence factor that is bilateral and does not represent the measurand

3.1.6
leakage rate
leakage, permeation and/or diffusion effects of the medium through the PMT and/or its mounting devices over the testing period under static pressure conditions, expressed as normal volume flow rate

Note: The CDD code of this entry for Electronic Data Exchange is ABD632

3.1.7
measuring range
range related to the measurement of absolute and gauge pressure PMTs

Note 1: For a pressure PMT with variable (adjustable or programmable) span, the measuring range and associated terms are shown in Figure 1.

Note 2: See also Annex C for an example of signal current range of a 4 mA to 20 mA PMT.

3.1.8
overpressure limit
proof pressure
multiple of indicated range with which the device may be subjected to pressure without permanent damage

Note 1: The output signal at the overpressure limit is sometimes unreliable and/or not predictable. The specification applies to the maximum permitted medium temperature.

Note 2: After returning to the measuring range, the guaranteed metrological properties shall remain unchanged.

Note 3: The CDD code of this entry for Electronic Data Exchange is ABC027.

3.1.9
pressure
force per unit area applied in a direction perpendicular to a surface

Note 1: The SI unit for pressure is the Pascal (Pa), equal to one Newton per square metre (N/m² or kg·m-1·s-2).

Note 2: In Annex A, a table shows the relationship between the SI unit and other units, often used for process measurement transmitter applications.

Note 3: For the purpose of this document, a simplified definition could be accepted as follows: "Ratio of orthogonal component of the force per unit area to that unit area".

3.1.10
variable scale pressure transmitter
pressure transmitter with an adjustable measuring range (turn-down ratio)

3.2 Terms related the process conditions

3.2.1
diaphragm seal
emote seal
functional component that transfers the pressure to be measured to the PMT by hydraulic path and decouples the PMT from influence factors stemming from the process

Note 1: A remote seal is connected to the transmitter by a capillary; the diaphragm seal is usually an integral part of the transmitter.

Note 2: The primary purpose of using diaphragm/remote seals is to protect the sensing element against high process temperatures or aggressive media.

Note 3: A diaphragm made of suitable material is responsible for the separation of the measured fluids/gases and transmitter. A fluid adapted to the measurement task is responsible for the transfer of the pressure to the measuring element.

Note 4: The diaphragm seal is included in the treatment of the total measurement error (e.g. temperature influence, step response time, vacuum stability, etc.).

3.2.2
manifold
pipe fitting or similar device, such as a flanged joint, that connects multiple inputs or outputs, allowing differential pressure PMTs to connect to the process

4 General description of the device and overview

The general description outlined in Clause 4 of GB/T 42567.1-2023 is applicable.

For the scope of this document, see a more detailed description of the functional blocks of an intelligent pressure PMT in Annex B.

5 Reference test conditions

To verify the influence of external quantities on accuracy as well as the mechanical and electrical conditions which a device can withstand and still work within specification, Clause 5 of GB/T 42567.1-2023 applies, both for standard reference test conditions and for operating reference test conditions.