1、BRITISH STANDARD BS 1646-2: 1983 Symbolic representation for process measurement control functions and instrumentation Part 2: Specification for additional basic requirements UDC53.08:681.2:003.62BS 1646-2:1983 This British Standard, having been prepared under the direction of the Industrial-process
2、 Measurement and Control Standards Committee, was published under the authority of the Board of BSI and comes intoeffect on 30 November 1983 BSI 01-1999 The following BSI references relate to the work on this standard: Committee reference PCL/4 Draft for comment78/31228 DC ISBN0580136272 Committees
3、responsible for this British Standard The preparation of this British Standard was entrusted by the Industrial-process Measurement and Control Standards Committee (PCL/-) to Technical Committee PCL/4 upon which the following bodies were represented: Association of Consulting Engineers Beama Transmis
4、sion and Distribution Association British Industrial Measuring and Control Apparatus Manufacturers Association (BEAMA) Energy Industries Council Institute of Measurement and Control Institution of Gas Engineers Ministry of Defence Amendments issued since publication Amd. No. Date of issue CommentsBS
5、 1646-2:1983 BSI 01-1999 i Contents Page Committees responsible Inside front cover Foreword ii 0 Introduction 1 1 Scope and field of application 1 2 References 1 3 Definitions 1 4 Letter code 1 5 Instrument signal lines 3 6 Primary elements, correcting elements, and actuating elements 3 7 Local cont
6、rol panels 5 8 Signal modifiers, analogue 6 9 Binary logic 7 10 Action of binary signals on analogue signals 7 Table Letter code for identification of instrument functions 2 List of references Inside back coverBS 1646-2:1983 ii BSI 01-1999 Foreword This British Standard has been prepared under the d
7、irection of the Industrial-process Measurement Control Standards Committee and is technically equivalent to the International Organization for Standardization (ISO) draft international standard ISO/DIS3511/2 “Process measurement control functions and instrumentation Symbolic representation, Part2:Ex
8、tension of basic requirements”. The decision to publish now rather than await the publication of the corresponding ISO standard, recognises the urgent need of the industry for a standard with worldwide application based on an international text. It is anticipated that any differences with the finall
9、y published ISO version will be of a minor nature. This standard incorporates minor editorial corrections to the ISO draft which have been submitted by the British Member Body to the ISO Technical Committee. For ease of production the text of the draft international standard has been used for this B
10、ritish Standard; some terminology and certain conventions are not identical with those used in British Standards. The rectangular symbols in accordance with IEC117-15, referred to in clause9, are identical with those given in BS3939-21. A British Standard does not purport to include all the necessar
11、y provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Cross-reference International standard Corresponding British Standard IEC117 BS3939 Graphical symbols fo
12、r electrical power, telecommunications and electronic diagrams (Technically equivalent) Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1to 8, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have h
13、ad amendments incorporated. This will be indicated in the amendment table on theinside front cover.BS 1646-2:1983 BSI 01-1999 1 0 Introduction This British Standard has been devised to provide a universal means of communication among the various interests involved in the design, manufacture, install
14、ation and operation of measurement and control equipment used in the process industries. Requirements within the industries vary considerably; in recognition of this, this British Standard is presented in several parts, as follows: Part1: Basic requirements (directed towards the needs of those emplo
15、ying comparatively simple measurements and control means); Part2: Extension of basic requirements; Part3: Detailed symbols for instrument interconnection diagrams; Part4: Basic symbols for process computer, interface, and shared display/control functions 1) . The four parts together are intended to:
16、 a) meet the requirements of those, possibly employing more sophisticated measurement and control means, who may wish to depict such aspects as the measurement techniques embodied in a particular instrument, or the means hydraulic, pneumatic, electrical, mechanical used for its actuation; b) provide
17、 standard symbolic representation for process measurement control functions and instrumentation. These symbols are not intended to replace graphic symbols for electrical equipment as contained in IEC Publication117. 1 Scope and field of application This Part of BS1646 is an extension of Part1, which
18、 is limited to identification of instrument functions. It includes additional symbols and is intended for the communication of measurement and control functions among instrument specialists and other engineers involved with vessels, piping, layout design and operation. The symbols are used on piping
19、 and instrumentation diagrams and engineering line diagrams. 2 Reference IEC117-15, Recommended graphical symbols; graphical symbols Part15: Binary logic elements. 3 Definitions The definitions given in BS1646-1 equally apply to this Part of BS1646. The following definition also applies: 3.1 sensing
20、 element that part of an instrument loop that first senses the value of a process variable and that assumes a predetermined and intelligible state or output NOTEThe sensing element may be separate from or integral with another functional element of a loop, but should be given an individual tag numbe
21、r only if it is separate. Examples: Where a direct-connected pressure transmitter has an integral pressure-sensitive element, the combined element and transmitter assembly shall be tagged PT. Where an external pressure cell is connected to a transmitter, the pressure cell shall be tagged PE and the
22、transmitter shall be tagged PT. 4 Letter code 4.1 Identifying letters The function of the instrument shall be defined by a letter code included within the instrument symbol circle. 4.2 Basis for the letter code The letter code is built up similarly to the letter code for basic symbols given in BS164
23、6-1 but the table extends the letters available for use. 1) At present at the stage of draft.BS 1646-2:1983 2 BSI 01-1999 Table Letter code for identification of instrument functions NOTEEntries in normal type are identical with the entries in the Table of BS1646-1. Entries in italics indicate the s
24、upplementary symbols. 1 2 3 4 First letter a Succeeding letter a Measured or initiating variable Modifier Display or output functions A Alarm B Display of state (e.g., motor running) C Controlling D Density Difference E All electrical variables b Sensing element F Flow rate Ratio G Gauging, position
25、 or length H Hand (manually initiated) operated I Indicating J Scan K Time or time programme L Level M Moisture or humidity N Users choice c Users choice c O Users choice c P Pressure or vacuum Test-point connection Q Quality b for example Analysis Integrate or totalise Integrating or summating Conc
26、entration Conductivity R Nuclear radiation Recording S Speed of frequency Switching T Temperature Transmitting U Multivariable d Multifunction unit V Viscosity Valve, damper, louvre, actuating element, unspecified correcting unit W Weight or force X Unclassified variables c Unclassified functions (f
27、or example cathode-ray tube) Y Users choice c Computing relay, relay Z Emergency or safety acting a Upper case letters shall be used for the measured or initiating variable and succeeding letters for display or output function. Upper case letters are preferred for modifiers, but lower case letters m
28、ay be used if this facilitates understanding. b A note shall be added to specify the property measured. c Where a user has a requirement for measured or initiating variables to which letters have not been allocated and are required for repetitive use on a particular contract, the letters allocated t
29、o “Users Choice” may be used provided that they are identified or defined for a particular measured or initiating variable and reserved for that variable. Where a user has a requirement for a measured or initiating variable that may be used either once or to a limited extent the letter X may be used
30、 provided that it is suitably identified or defined. d The letter U may be used instead of a series of first letters where a multiplicity of inputs representing dissimilar variables feed intoa single unit. NOTEWhere it is necessary to denote HIGH or LOW, the qualifying letters H or L may be used in
31、association with the instrument symbol. Other letters may be used, for example for deviation, for rate of change, etc. but must be defined on the drawing rather than the table.BS 1646-2:1983 BSI 01-1999 3 5 Instrument signal lines 5.1 Electric (E) 5.2 Pneumatic (A) 5.3 Hydraulic (L) 5.4 Capillary 5.
32、5 Conducted radiation (radio waves, visible light) 6 Primary elements, correcting elements, and actuating elements NOTEIn cases where it is necessary to use detail symbols in functional diagrams the symbols should be as given in BS 1646-3, simplifying if possible. Examples are as follows. 6.1 Flow p
33、rimary elements 6.1.1 Orifice plate 6.1.2 Venturi tube 6.1.3 Nozzle 6.1.4 Variable area meter 6.1.5 Turbine meter 6.1.6 Volume meter generalBS 1646-2:1983 4 BSI 01-1999 6.1.7 Any other flow primary element 6.2 Level instrument connections 6.2.1 Integrally mounted instrument, for example welded-on ty
34、pe 6.2.2 Instrument with single connection, for example internal-float type 6.2.3 Instrument with two connections, for example external displacer type 6.2.4 Tank gauge-float type 6.2.5 Tank gauge-float type, top-mounted 6.2.6 Level control valve mechanical linkage 6.3 Pressure regulators, self-actua
35、ted 6.3.1 Pressure regulator with internal tap 6.3.2 Pressure regulator with external tap 6.3.3 Differential-pressure regulator with external tapsBS 1646-2:1983 BSI 01-1999 5 6.4 Actuating elements (where it is desired to show the type of actuating element) 6.4.1 Diaphragm actuator 6.4.2 Diaphragm a
36、ctuator, pressure-balanced 6.4.3 Rotary motor actuator 6.4.4 Solenoid actuator (Preferred side relationship1:2) 6.4.5 Piston actuator (Preferred side relationship1:2) 6.4.6 Solenoid actuator with reset (manual) 6.4.7 Solenoid actuator with reset (remote electrical) 7 Local control panels Instruments
37、 on local control panels can be specified by an additional horizontal line across the symbol. The particular panel can be identified by a note alongside the symbol, for example: Compressor Pressure indicator on the compressor panel Services Flow recorder on the services panelBS 1646-2:1983 6 BSI 01-
38、1999 8 Signal modifiers, analogue Lower case letter designations (for example a1, a2, etc.) are standardized values of signals, shown for descriptive purposes only. They are not part of the symbol. Other arithmetic functions may be similarly treated. Upper case letters (for exampleZ) represent signa
39、ls without specific values. 8.1 Addition For example, flow signals 8.2 Root extraction (square root) For example, flow signal 8.3 Limitation of output when a hand-set high-limit value is reached (same as selecting lower signal) For example, temperature controller signal when a1 a2 then Z = a1 8.5 Hi
40、gh-signal selector For example, pressure signals when a1 $ a2 then Z = a1 when a1 a2 then Z = a2 when a1 # a2 then Z = a1 8.7 Reversing relay For example, pressure signal Z =1 a 8.8 Volume booster For example, level controller signalBS 1646-2:1983 BSI 01-1999 7 8.9 Gain or attenuation relay For exam
41、ple, flow signals 8.10 Characterizing relay f (x) For example, flow signal 8.11 Digital-to-analogue or analogue-to-digital signal converter For example, pressure signals 8.12 On-off relay1-0 For example, temperature analogue input signal with binary output signal 8.13 Bias relay , + or , representin
42、g relays respectively for plus-or-minus adjustability, for addition, or for subtraction. For example, flow signal, with adjustable plus or minus bias, k 9 Binary logic The basic elements are “and”, “or”, “not” and “delay elements” and these shall have rectangular symbols in accordance with IEC11715.
43、 10 Action of binary signals on analogue signals When an input analogue signal A is influenced by a binary signal B, the output analogue signal Z can a) retain the last value; or b) assume a predetermined minimum value; or c) assume a predetermined maximum value; or d) assume some other predetermine
44、d value. This may occur in both the1-state and the0-state of the binary signal. Diagrams are shown with electrical signals but are otherwise typical for all signals. Where “A”, “Z”, etc., appear in the examples, they are not a part of the symbol. They are there for clarity of the symbol. 10.1 When B
45、 =1, then Z = A. When B =0, then there are four possibilities as follows: 10.1.1 Z retains the last momentary value (N)BS 1646-2:1983 8 BSI 01-1999 10.1.2 Z assumes the minimum value 10.1.3 Z assumes the maximum value 10.1.4 Z assumes a predetermined value, for example 70% 10.2 When B =0, then Z = A
46、. When B =1, then there are four possibilities, as follows: 10.2.1 Z retains the last momentary value N 10.2.2 Z assumes the minimum value 10.2.3 Z assumes the maximum value 10.2.4 Z assumes a predetermined value, for example70%BS 1646-2:1983 BSI 01-1999 Publications referred to BS1646, Symbolic rep
47、resentation for process measurement control functions and instrumentation. BS1646-1, Basic requirements. BS1646-3, Specification for detailed symbols for instrument interconnection diagrams. See also foreword.BSI 389 Chiswick High Road London W4 4AL | | | | | | | | | | | | | | | | | | | | | | | | |
48、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BSI British Standards Institution BSI is the independent national body responsible for preparing
49、 British Standards. It presents the UK view on standards in Europe and at the international level. It is incorporated by Royal Charter. Revisions British Standards are updated by amendment or revision. Users of British Standards should make sure that they possess the latest amendments or editions. It is the constant aim of BSI to improve the quality of our products and services. We would be grateful if anyone finding an inaccuracy or ambiguity while using this British Standard would inform the Secretary of the technical committee
