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HG/T 20507-2014 English PDF (HGT20507-2014)

HG/T 20507-2014 English PDF (HGT20507-2014)

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HG/T 20507-2014: Design code for instrument selection
HG/T 20507-2014
HG
CHEMICAL INDUSTRY STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
File No.: J 1809-2014
Replacing HG/T 20507-2000
Design code for instrument selection
ISSUED ON: MAY 06, 2014
IMPLEMENTED ON: OCTOBER 01, 2014
Issued by: Ministry of Industry and Information Technology of the People’s
Republic of China.
Table of Contents
Foreword ... 5
1 General provisions ... 7
2 Terms ... 8
3 General requirements ... 10
4 Temperature instrument ... 11
4.1 General requirements ... 11
4.2 Local temperature gauge ... 12
4.3 Temperature instrument for centralized detection ... 13
5 Pressure instrument ... 16
5.1 General requirements ... 16
5.2 Selection of pressure gauge ... 16
5.3 Selection of transmitter ... 17
6 Flow instrument ... 19
6.1 General requirements ... 19
6.2 Selection of differential pressure flowmeter ... 21
6.3 Variable area flowmeter (rotameter) ... 22
6.4 Velocity flowmeter ... 23
6.5 Positive displacement flowmeter ... 24
6.6 Magnetic flowmeter ... 24
6.7 Ultrasonic flowmeter ... 25
6.8 Coriolis mass flowmeter ... 25
6.9 Thermal mass flowmeter ... 25
6.10 Impulse flowmeter ... 25
6.11 Conveyer belt scale ... 26
6.12 Flow switch ... 26
7 Level instrument ... 27
7.1 General requirements ... 27
7.2 Liquid level and interface measuring instrument ... 28
7.3 Solid level measuring instrument ... 34
8 Online analytical instrument ... 36
8.1 General requirements ... 36
8.2 Requirements for sampling pipe ... 36
8.3 Preconditioning device ... 37
8.4 Analytical instrument for liquid service ... 37
8.5 Analytical instrument for gas service ... 38
8.6 Installation of online analytical instrument ... 39
9 Display control instrument ... 41
9.1 General requirements ... 41
9.2 Selection of display instrument ... 42
9.3 Selection of control instrument ... 44
10 Instrument panel ... 46
10.1 General requirements ... 46
10.2 Selection of instrument panel ... 46
11 Control valve ... 47
11.1 General requirements ... 47
11.2 Control valve ... 47
11.3 On-off valve ... 50
11.4 Material of control valve ... 51
11.5 Structure and material of packing box assembly of control valve ... 52
11.6 Upper valve cover type of control valve ... 52
11.7 Flow opening and closing of control valve ... 53
11.8 Control valve actuator ... 53
11.9 Accessories of control valve ... 54
11.10 Fail position of control valve ... 56
12 Other instrument ... 57
12.1 General requirements ... 57
12.2 Rotary speed measuring instrument ... 57
12.3 Axial displacement measuring instrument ... 57
12.4 Axial vibration measuring instrument ... 57
12.5 Weighing instrument ... 57
Appendix A -- Selection of flow gauge (normative) ... 59
Explanation of wording in this standard ... 61
Normative standards ... 62
Design code for instrument selection
1 General provisions
1.0.1 This Code was formulated in order to unify the technical requirements for the
selection of measurement and control instruments in the chemical industry, promote the
standardization of engineering design for the selection of chemical measurement and
control instruments, and achieve the goals of technological advancement, economical
rationality, safety and applicability.
1.0.2 This Code is applicable to the selection and design of measurement and control
instruments in new construction, expansion and renovation projects in the chemical
industry.
1.0.3 In addition to complying with the requirements of this Code, the selection and
design of measurement and control instruments shall also comply with the relevant
current national standards.
4 Temperature instrument
4.1 General requirements
4.1.1 The unit and measuring range of temperature instruments shall meet the following
requirements:
1 The unit of temperature instruments shall use Celsius (°C).
2 The measurement of temperature instruments shall use direct reading type.
3 The measuring range of temperature instruments should be consistent with the
standard series of finalized products.
4.1.2 The immersion depth of temperature detection elements shall meet the following
requirements:
1 The selection of the immersion depth of temperature detection elements shall be
based on the principle that the temperature detection element is inserted into a
representative area where the temperature of the measured medium changes
sensitively.
2 When a temperature detection element is installed vertically on a full fluid pipeline
or at an angle of 45° to the pipe wall, the length of the end of the temperature
detection element immersed in the inner wall of the pipeline shall not be less than
50 mm and should not be greater than 125 mm.
3 When a temperature detection element is installed on the equipment, the length of
the end of the temperature detection element immersed in the inner wall of the
equipment shall not be less than 150 mm. When installed on flues, furnaces and
insulating masonry equipment, it shall be selected according to actual needs.
4.1.3 The selection of protective sleeves for temperature detection elements shall meet
the following requirements:
1 The material of protective sleeve for temperature detection elements shall be
selected according to the design temperature, design pressure and anti-corrosion
requirements of the pipeline and the characteristics of the measured medium.
2 The protective sleeve for temperature detection elements should select an
integrally drilled tapered protective sleeve.
3 In situations where the temperature, pressure and flow rate of the process fluid are
high, it should perform vibration calculations on the protective sleeve.
4 The detection elements used for measurement of ambient temperature and surface
temperature shall not use protective sleeves, but should use armored temperature
detection elements or assembled temperature detection elements.
4.2 Local temperature gauge
4.2.1 The selection of the accuracy level of local temperature instruments shall meet
the following requirements:
1 It should select grade 1.5 for industrial thermometers.
2 It shall select grade 0.5 or grade 0.25 for thermometers used for precision
measurement.
4.2.2 The selection of the measuring range of local temperature instruments shall meet
the following requirements:
1 The maximum measured value shall not be greater than 90 % of the upper limit of
the instrument’s measuring range, and the normal measured value should be
around 50 % of the upper limit of the instrument’s measuring range.
2 The measured value of pressure thermometers shall be between 50 % and 75 % of
the upper limit of the instrument’s measuring range.
3 For measurements of low temperature below 0 °C, the upper limit of the
instrument’s measuring range shall cover the ambient temperature.
4.2.3 The selection of bimetal thermometers shall meet the following requirements:
1 For local temperature detection, it should select a bimetal thermometer.
2 The diameter of the bimetal thermometer shell should be φ100 mm. In places with
poor lighting conditions, high installation positions or long observation distances,
it shall select φ150 mm.
3 For the connection method between the bimetal thermometer instrument shell and
the protective tube, it should select the universal type, or it can select the axial
type or the radial type according to the principle of convenient observation.
4.2.4 For local or local panel d...
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