литература / Функциональные схемы автоматизации / ANSI_ISA 5.1 2009 - Instrumentation Symbols and Identification

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Annex B Graphic symbol guidelines (informative annex)

B.1 Graphic symbols

B.1.1 This informative annex to the standard describes the use of graphic symbols that are used to depict instrument loop devices and functions, application software functions, and the interconnections between them that is logical, unique, and consistent in application with a minimum of exceptions, special uses, or requirements.

B.1.2 Graphic symbols, when used with identification letters and numbers constructed as described in Annex A, should as a minimum describe the functionality of, and if assigned a loop number provide a unique identity for, each device and function shown.

B.2 Instrument identification applied to graphic symbols

B.2.1 Instrument identification applied to graphic symbols should include, as a minimum, an alphabetic functional identification to identify the functionality of devices and functions shown in the diagrams as described in Annex A.

B.2.2 Tables A.3.1.1 through A.3.6.2 provide examples of allowable functional identifications.

B.2.3 Brief explanatory notes or other text may be added adjacent to a symbol or in the note section of a drawing or sketch to clarify the meaning or purpose of a device or function.

B.2.4 Loop Identification Number numerals, when assigned in accordance with A.6, complete the identity of the loop being shown.

B.2.5 Lettering fonts should be similar to Arial Narrow and be a minimum of 3/32in(1.125mm) high and a maximum of 13 characters per inch wide.

B.2.6 A Loop Number prefix should:

a)Not be used with bubbles on drawings but indicated in the note section.

b)Be used with bubbles if more than one prefix is being used.

c)Be used in text.

Letters and the lower half of each symbol for Loop Numbers:

a)Five (5) characters or less:

ABCDE

98765

b)Six (6) characters or more, relieve sides of bubble or enlarge bubble as required:

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B.5.2

B.5.3

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B.6.1

It is not necessary to show a symbol or a bubble for every device or function required by a loop if the need for the device or function or its tag number is clearly understood; for example:

a)Symbols are not required, but may be used, for control valve positioners and stream sample conditioner components.

b)Bubbles are not required, but may be used, for orifice plate, thermocouple, and control valve graphic symbols.

When “smart” drawings, such as computer-generated P&IDs, that are linked to instrument indexes or data sheets are used, a bubble or graphic symbol to which an instrument tag number is attached should be used for all devices and functions that are to be indexed or require data sheets.

Instrument diagram and functional diagram example

Process Flow Diagrams (PFDs) are developed by process engineers to provide basic process data and to describe process operation. Simple instrument diagrams are used to indicate the primary process control measurements and controlled streams required to operate the process. Process monitoring and alarm points and secondary and auxiliary controls and monitors are not shown but are added during the detailed process design and P&ID development.

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B.6.4 Typical equipment and function-oriented functional diagrams developed from the PFD diagram:

B.7 Process variable measurements

B.7.1 Process variable measurement devices are inserted in or mounted on pipelines and equipment to measure a physical property or to analyze a chemical composition, and include but are not limited to:

a)Primary elements, such as orifice plates and thermocouples, that generate analog signals, position mechanical devices, or are used by transmitters to generate signals compatible with the control system.

b)Transmitters with integral primary elements, such as vortex shedding flowmeters and filled-capillary temperature devices that generate signals compatible with the control system.

B.7.2 Process measurements are indicated by:

a)Bubbles as shown in Table 5.2.1 for:

1)Generic primary elements.

2)Primary elements that do not have a graphic symbol in Table 5.2.3.

3)Users who elect not to use graphic symbols from Table 5.2.3.

b)Graphic symbols from Table 5.3.2.

B.7.3 Analyzer primary element located in a process slip stream or in a process stream or equipment with or without accessory devices, such as sample conditioners that contain components that are not normally shown, and with type of analyzer and component of interest noted at (**) and (***) respectively:

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B.7.6 Orifice meter tubes or runs that are specified and requisitioned by the instrument group should be shown on drawings and sketches by:

a)Bubble: FX

B.8 Final control elements

B.8.1 Final control elements installed in pipelines and equipment modulate or manipulate the process stream or equipment to affect the loop measured variable.

B.8.2 Final control elements include, but are not limited to, control valves, solenoid valves, louvers, dampers, motors, variable speed drives, and machine components.

B.8.3 Control valves are generally pneumatically operated and furnished with positioners that may:

b)With positioner:

1)Cross-hatches from positioner to actuator are optional.

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c)Is an integral assembly that contains a transmitter, a controller, and a control valve:

FC 101

B.9 Common instrument-to-instrument signal connections B.9.1 Pneumatic discrete instrumentation:

FV *01

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B.9.9 Fieldbus valve positioner/controller, transmitter, and indicator:

B.9.10 Fieldbus integral transmitter, controller, and valve positioner:

B.10.1 Signal processing functions should be identified by a function block symbol from Table 7.6 that is:

a)Appended to a bubble if an Instrument/Tag Number is required:

Σ

FY

*012

b)Attached tangentially to the affected bubble and in line with the signal if the function is an integral part of the affected bubble:

Σ FI *012