ISA STANDARD 5.1 P&ID

1. GAMBARAN UMUM TENTANG ISA S 5.1 

Tujuan standar ini adalah untuk menetapkan cara yang seragam untuk menentukan instrumen dan sistem instrumentasi yang digunakan untuk pengukuran dan kontrol. Untuk tujuan ini, sistem penunjukan yang mencakup simbol dan kode identifikasi disajikan.

Cakupan Aplikasi

Cara-cara yang dibutuhkan untuk memberikan informasi mengenai operasi proses oleh berbagai pengguna bisa berbeda-beda, maka perlu mengenal standar simbol agar dapat menggambarkan dan menjelaskan apa yang diinginkan pengguna mengenai instrumentasi

-       Aplikasi Industri

Standar simbol instrumen banyak digunakan di industri chemical, petroleum, power generation, air conditioning, dan proses lndusttri lainnya seperti astronomy, navigation, and medicine, yang menggunakan instrumen yang sangat khusus

-       Applikasi untuk aktifitas pekerjaan

Standar sangat cocok untuk digunakan pada sistem control dan instrumen untuk maksud melambangkan dan identifikasi yang diperlukan pengguna seperti

• Design sketches

• Teaching examples

• Technical papers, literature, and discussions

• Instrumentation system diagrams, loop diagrams, logic diagrams

• Functional descriptions

• Flow diagrams: Process, Mechanical, Engineering, Systems, Piping (Process) and Instrumentation

• Construction drawings

• Specifications, purchase orders, manifests, and other lists

• Identification (tagging) of instruments and control functions

• Installation, operating and maintenance instructions, drawings, and records

Standar dimaksudkan untuk memberikan informasi kepada seseorang meninjau beberapa dokumen mengenai proses pengukuran dan kontrol, untuk mengetahui maksud dari pengukuran dan pengontrolan proses

-  Aplikasi untuk kelas instrumentasi dan fungsi instrumen

Metode simbol dan identifikasi dalam standar ini dapat dipakai untuk semua tingkatan pengukuran proses dan instrumen kontrol. Ini juga digunakan tidak hanya untuk menggambarkan instrumen-instrumen diskrit dengan fungsinya, tetapi juga untuk menggambarkan fungsi-fungsi sistem analog yang bervariasi misal bagian-bagian display, kontrol, distributed control, dan computer control.  

-      Tingkat identifikasi fungsional

Standar ini menyediakan identifikasi dan simbolisasi fungsi-fungsi utama suatu instrumen. Rincian tambahan dari instrumen lebih baik dijelaskan dalam spesifikasi yang sesuai, lembar data, atau dokumen lain yang ditujukan bagi mereka yang membutuhkan detail tersebut.

-       Extent of loop identification

The standard covers the identification of an instrument and all other instruments or control

functions associated with it in a loop. The user is free to apply additional identification — by

serial number, unit number, area number, plant number, or by other means.

2 DEFINISI

Untuk maksud lebih mengerti tentang standar ini berikut ini beberapa istilah yang digunakan:

Accessible: A term applied to a device or function that can be used or be seen by an operator for the purpose of performing control actions, e.g., set point changes, auto-manual transfer, or on-off actions.

Alarm: A device or function that signals the existence of an abnormal condition by means of an audible or visible discrete change, or both, intended to attract attention. It is not recommended that the term alarm switch or alarm be used to designate a device whose

operation is simply to close or open a circuit that may or may not be used for normal or abnormal interlock, start-up, shutdown, actuation of a pilot light or an alarm device, or the like. The first device is properly designated as a level switch, a flow switch, etc., because "switching" is what the device does. The device may be designated as an alarm only if the device itself contains the alarm function. [See also Table 1, note (13).]

Assignable: A term applied to a feature permitting the channeling (or directing) of a signal from one device to another without the need for switching, patching, or changes in wiring.

Auto-manual station: Synonym for control station.

Balloon: Synonym for bubble.

Behind the panel: A term applied to a location that is within an area that contains (1) the instrument panel, (2) its associated rack-mounted hardware, or (3) is enclosed within the panel. Behind the panel devices are not accessible for the operator's normal use, and are not designated as local or front-of-panel-mounted. In a very broad sense, "behind the panel" is equivalent to "not normally accessible to the operator."

Binary: A term applied to a signal or device that has only two discrete positions or states. When used in its simplest form, as in "binary signal" (as opposed to "analog signal"), the term denotes an "on-off" or "high-low" state, i.e., one which does not represent continuously varying quantities.

Board: Synonym for panel.

Bubble: The circular symbol used to denote and identify the purpose of an instrument or

function. It may contain a tag number. Synonym for balloon.

Computing device: A device or function that performs one or more calculations or logic operations, or both, and transmits one or more resultant output signals. A computing device is sometimes called a computing relay.

Configurable: A term applied to a device or system whose functional characteristics can be

selected or rearranged through programming or other methods. The concept excludes rewiring as a means of altering the configuration.

Controller: A device having an output that varies to regulate a controlled variable in a specified manner. A controller may be a self-contained analog or digital instrument, or it may be the equivalent of such an instrument in a shared-control system.

An automatic controller varies its output automatically in response to a direct or indirect input of a measured process variable. A manual controller is a manual loading station, and its output is not dependent on a measured process variable but can be varied only by manual adjustment. A controller may be integral with other functional elements of a control loop.

Control station: A manual loading station that also provides switching between manual and

automatic control modes of a control loop. It is also known as an auto-manual station. In addition, the operator interface of a distributed control system may be regarded as a control

station.

Control valve: A device, other than a common, hand-actuated ON-OFF valve or self-actuated check valve, that directly manipulates the flow of one or more fluid process streams. It is expected that use of the designation "hand control valve" will be limited to hand-actuated valves that (1) are used for process throttling, or (2) require identification as an instrument.

Converter: A device that receives information in one form of an instrument signal and transmits an output signal in another form. An instrument which changes a sensor's output to a standard signal is properly designated as a transmitter, not a converter. Typically, a temperature element (TE) may connect to a transmitter (TT), not to a converter (TY).

A converter is also referred to as a transducer; however, "transducer" is a completely general term, and its use specifically for signal conversion is not recommended.

Digital: A term applied to a signal or device that uses binary digits to represent continuous

values or discrete states.

Distributed control system: A system which, while being functionally integrated, consists of

subsystems which may be physically separate and remotely located from one another.

Final control element: The device that directly controls the value of the manipulated variable of a control loop. Often the final control element is a control valve.

Function: The purpose of, or an action performed by, a device.

Identification: The sequence of letters or digits, or both, used to designate an individual

instrument or loop.

Instrument: A device used directly or indirectly to measure and/or control a variable. The term includes primary elements, final control elements, computing devices, and electrical devices such as annunciators, switches, and pushbuttons. The term does not apply to parts (e.g., a receiver bellows or a resistor) that are internal components of an instrument.

Instrumentation: A collection of instruments or their application for the purpose of observation, measurement, control, or any combination of these.

Local: The location of an instrument that is neither in nor on a panel or console, nor is it mounted in a control room. Local instruments are commonly in the vicinity of a primary element or a final control element. The word "field" is often used synonymously with local.

Local panel: A panel that is not a central or main panel. Local panels are commonly in the

vicinity of plant subsystems or sub-areas. The term "local panel instrument" should not be

confused with "local instrument."

Loop: A combination of two or more instruments or control functions arranged so that signals pass from one to another for the purpose of measurement and/or control of a process variable.

Manual loading station: A device or function having a manually adjustable output that is used to actuate one or more remote devices. The station does not provide switching between manual and automatic control modes of a control loop (see controller and control station). The station may have integral indicators, lights, or other features. It is also known as a manual station or a manual loader.

Measurement: The determination of the existence or the magnitude of a variable.

Monitor: A general term for an instrument or instrument system used to measure or sense the status or magnitude of one or more variables for the purpose of deriving useful information. The term monitor is very unspecific — sometimes meaning analyzer, indicator, or alarm. Monitor can also be used as a verb.

Monitor light: Synonym for pilot light.

Panel: A structure that has a group of instruments mounted on it, houses the operator-process interface, and is chosen to have a unique designation. The panel may consist of one or more sections, cubicles, consoles, or desks. Synonym for board.

Panel-mounted: A term applied to an instrument that is mounted on a panel or console and is accessible for an operator's normal use. A function that is normally accessible to an operator in a shared-display system is the equivalent of a discrete panel-mounted device.

Pilot light: A light that indicates which of a number of normal conditions of a system or device exists. It is unlike an alarm light, which indicates an abnormal condition. The pilot light is also known as a monitor light.

Primary element: Synonym for sensor.

Process: Any operation or sequence of operations involving a change of energy, state, composition, dimension, or other properties that may be defined with respect to a datum.

Process variable: Any variable property of a process. The term process variable is used in this standard to apply to all variables other than instrument signals.

Program: A repeatable sequence of actions that defines the status of outputs as a fixed relationship to a set of inputs.

Programmable logic controller: A controller, usually with multiple inputs and outputs, that

contains an alterable program.

Relay: A device whose function is to pass on information in an unchanged form or in some

modified form. Relay is often used to mean computing device. The latter term is preferred.

The term "relay" also is applied specifically to an electric, pneumatic, or hydraulic switch that is actuated by a signal. The term also is applied to functions performed by a relay.

Scan: To sample, in a predetermined manner, each of a number of variables intermittently. The function of a scanning device is often to ascertain the state or value of a variable. The device may be associated with other functions such as recording and alarming.

Sensor: That part of a loop or instrument that first senses the value of a process variable, and that assumes a corresponding, predetermined, and intelligible state or output. The sensor may be separate from or integral with another functional element of a loop. The sensor is also known as a detector or primary element.

Set point: An input variable that sets the desired value of the controlled variable. The set point may be manually set, automatically set, or programmed. Its value is expressed in the same units as the controlled variable.

Shared controller: A controller, containing preprogrammed algorithms that are usually accessible, configurable, and assignable. It permits a number of process variables to be

controlled by a single device.

Shared display: The operator interface device (usually a video screen) used to display process control information from a number of sources at the command of the operator.

Switch: A device that connects, disconnects, selects, or transfers one or more circuits and is not designated as a controller, a relay, or a control valve. As a verb, the term is also applied to the functions performed by switches.

Test point: A process connection to which no instrument is permanently connected, but which is intended for the temporary or intermittent connection of an instrument.

Transducer: A general term for a device that receives information in the form of one or more

physical quantities, modifies the information and/or its form, if required, and produces a resultant output signal. Depending on the application, the transducer can be a primary element, transmitter, relay, converter or other device. Because the term "transducer" is not specific, its use for specific applications is not recommended.

Transmitter: A device that senses a process variable through the medium of a sensor and has an output whose steady-state value varies only as a predetermined function of the process variable. The sensor may or may not be integral with the transmitter.

3. SYMBOLS s

1 The examples in this standard illustrate the symbols that are intended to depict instrumentation on diagrams and drawings. Methods of symbolization and identification are demonstrated. The examples show identification that is typical for the pictured instrument or functional interrelationships.

The symbols indicating the various instruments or functions have been applied in typical

ways in the illustrations. This usage/PENGGUNAAN does not imply, however, that the applications or designations of the instruments or functions are restricted in any way. No inference should be drawn that the choice of any of the schemes for illustration constitutes a recommendation for the illustrated methods of measurement or control. Where alternative symbols are shown without a statement of preference, the relative sequence of symbols does not imply a preference.

2 The bubble may be used to tag distinctive symbols, such as those for control valves, when such tagging is desired. In such instances, the line connecting the bubble to the instrument symbol is drawn close to, but not touching, the symbol. In other instances, the bubble serves to represent the instrument proper.

3 A distinctive symbol whose relationship to the remainder of the loop is easily apparent from a diagram need not be individually tagged on the diagram. For example, an orifice flange or a control valve that is part of a larger system need not be shown with a tag number on a diagram. Also, where there is a primary element connected to another instrument on a diagram, use of a symbol to represent the primary element on the diagram is optional.

4 A brief explanatory notation may be added adjacent to a symbol or line to clarify the function of an item. For instance, the notations 3-9 psig and 9-15 psig adjacent to the signal lines to two valves operating in split range, taken together with the symbols for the failure modes, allow complete understanding of the intent. Similarly, when two valves are operated in a diverting or mixing mode from a common signal, the notations 3-15 psig and 15-3 psig, together with the failure modes, allow understanding of the function.

5 The sizes of the tagging bubbles and the miscellaneous symbols shown in the examples are the sizes generally recommended; however, the optimum sizes may vary depending on whether or not the finished diagram is to be reduced in size and depending on the number of characters that are expected in the instrument tagging designation. The sizes of the other symbols may be selected as appropriate to accompany the symbols of other equipment on a diagram.

6 Aside from the general drafting requirements for neatness and legibility, symbols may be drawn with any orientation. Likewise, signal lines may be drawn on a diagram entering or leaving the appropriate part of a symbol at any angle. However, the function block designators of Table 3 and the tag numbers should always be drawn with a horizontal orientation. Directional arrowheads should be added to signal lines when needed to clarify the direction of flow of information. The judicious use of such arrowheads, especially on complex drawings, will often facilitate understanding of the system.

7 The electrical, pneumatic, or other power supply to an instrument is not expected to be shown unless it is essential to an understanding of the operation of the instrument or the loop.

8 In general, one signal line will suffice to represent the interconnections between two instruments on flow diagrams even though they may be connected physically by more than one line.

9 The sequence in which the instruments or functions of a loop are connected on a diagram should reflect the functional logic or information flow, although this arrangement will not necessarily correspond to the signal connection sequence. Thus, an electronic loop using analog voltage signals requires parallel wiring, while a loop using analog current signals requires series interconnections.

However, the diagram in both instances should be drawn as though all the wiring were

parallel, to show the functional interrelationships clearly while keeping the presentation independent of the type of instrumentation finally installed. The correct interconnections are expected to be shown on a suitable diagram.

10 The degree of detail to be applied to each document or sketch is entirely at the discretion of the user of the standard. The symbols and designations in this standard can depict both hardware and function. Sketches and technical papers will usually contain highly simplified symbolism and identification. Process flow diagrams will usually be less detailed than engineering flow diagrams.

Engineering flow diagrams may show all in-line components, but may differ from user to user in the amount of off-line detail shown. In any case, consistency should be established for each application. The terms simplified, conceptual, and detailed as applied to the diagrams of 6.12 were chosen to represent a cross section of typical usage. Each user must establish the degree of detail that fulfills the purposes of the specific document or sketch being generated.

11 It is common practice for engineering flow diagrams to omit the symbols of interlockhardware components that are actually necessary for a working system, particularly when symbolizing electric interlock systems. For example, a level switch may be shown as tripping a pump, or separate flow and pressure switches may be shown as actuating a solenoid valve or other interlock devices. In both instances, auxiliary electrical relays and other components may be considered details to be shown elsewhere. By the same token, a current transformer sometimes will be omitted and its receiver shown connected directly to the process — in this case the electric motor.

12 Because the distinctions between shared display/shared control and computer functions are sometimes blurred, in choosing symbols to represent them the user must rely on manufacturers' definitions, usage in a particular industry, and personal judgment.

4 TABEL

The purpose of  Tables, is to define certain of the building blocks of the identification and symbolic representation system used in this standard in a concise, easily-referenced manner.

Table 1, Identification Letters, together with the Notes for Table 1, define and explain the

individual letter designators used as functional identifiers in accordance with the rules of  Functional Identification.

1 Notes for Table 1

1) A "user's choice" letter is intended to cover unlisted meanings that will be used repetitively in a particular project. If used, the letter may have one meaning as a firstletter and another meaning as a succeeding-letter. The meanings need to be defined only once in a legend, or other place, for that project. For example, the letter N may be defined as "modulus of elasticity" as a first-letter and "oscilloscope" as a succeeding-letter.

2) The unclassified letter X is intended to cover unlisted meanings that will be used only once or used to a limited extent. If used, the letter may have any number of meanings as a first-letter and any number of meanings as a succeeding-letter. Except for its use with distinctive symbols, it is expected that the meanings will be defined outside a tagging bubble on a flow diagram. For example, XR-2 may be a stress recorder and XX-4 may be a stress oscilloscope.

3) The grammatical form of the succeeding-letter meanings may be modified as required.

For example, "indicate" may be applied as "indicator" or "indicating," "transmit" as "transmitter" or "transmitting," etc.

4) Any first-letter, if used in combination with modifying letters D (differential), F (ratio), M (momentary), K (time rate of change), Q (integrate or totalize), or any combination of these is intended to represent a new and separate measured variable, and the combination is treated as a first-letter entity. Thus, instruments TDI and TI indicate two different variables, namely, differential-temperature and temperature. Modifying letters are used when applicable.

5) First-letter A (analysis) covers all analyses not described by a "user's choice" letter.

It is expected that the type of analysis will be defined outside a tagging bubble.

6) Use of first-letter U for "multivariable" in lieu of a combination of first-letters is optional.

It is recommended that nonspecific variable designators such as U be used sparingly.

7) The use of modifying terms "high," "low," "middle" or "intermediate," and "scan" is optional.

8) The term "safety" applies to emergency protective primary elements and emergency protective final control elements only. Thus, a self-actuated valve that prevents operation of a fluid system at a higher-than-desired pressure by bleeding fluid from the system is a back-pressure-type PCV, even if the valve is not intended to be used normally. However, this valve is designated as a PSV if it is intended to protect against emergency conditions, i.e., conditions that are hazardous to personnel and/or equipment and that are not expected to arise normally.

The designation PSV applies to all valves intended to protect against emergency pressure conditions regardless of whether the valve construction and mode of operation place them in the category of the safety valve, relief valve, or safety relief valve. A rupture disc is designated PSE.

9) The passive function G applies to instruments or devices that provide an uncalibrated view, such as sight glasses and television monitors.

10) "Indicate" normally applies to the readout—analog or digital—of an actual measurement. In the case of a manual loader, it may be used for the dial or setting indication, i.e., for the value of the initiating variable.

11) A pilot light that is part of an instrument loop should be designated by a first-letter followed by the succeeding-letter L. For example, a pilot light that indicates an expired time period should be tagged KQL. If it is desired to tag a pilot light that is not part of an instrument loop, the light is designated in the same way. For example, a running light for an electric motor may be tagged EL, assuming voltage to be the appropriate measured variable, or YL, assuming the operating status is being monitored. The unclassified variable X should be used only for applications which are limited in extent.

The designation XL should not be used for motor running lights, as these are commonly numerous. It is permissible to use the user's choice letters M, N or O for a motor running light when the meaning is previously defined. If M is used, it must be clear that the letter does not stand for the word "motor," but for a monitored state.

12) Use of a succeeding-letter U for "multifunction" instead of a combination of other functional letters is optional. This nonspecific function designator should be used sparingly.

13) A device that connects, disconnects, or transfers one or more circuits may be either a switch, a relay, an ON-OFF controller, or a control valve, depending on the application. If the device manipulates a fluid process stream and is not a hand-actuated ON-OFF block valve, it is designated as a control valve. It is incorrect to use the succeeding-letters CV for anything other than a self-actuated control valve. For all applications other than fluid process streams, the device is designated as follows:

• A switch, if it is actuated by hand.

• A switch or an ON-OFF controller, if it is automatic and is the first such device in a loop.

  The term "switch" is generally used if the device is used for alarm, pilot light, selection,

   interlock, or safety.

• The term "controller" is generally used if the device is used for normal operating control.

• A relay, if it is automatic and is not the first such device in a loop, i.e., it is actuated by a

  switch or an ON-OFF controller.

14) It is expected that the functions associated with the use of succeeding-letter Y will be defined outside a bubble on a diagram when further definition is considered necessary. This definition need not be made when the function is self-evident, as for a solenoid valve in a fluid signal line.

15) The modifying terms "high," and "low," and "middle" or "intermediate" correspond to values of the measured variable, not to values of the signal, unless otherwise noted. For example, a high-level alarm derived from a reverse-acting level transmitter signal should be an LAH, even though the alarm is actuated when the signal falls to a low value. The terms may be used in combinations as appropriate.

16) The terms "high" and "low," when applied to positions of valves and other open-close devices, are defined as follows: "high" denotes that the valve is in or approaching the fully open position, and "low" denotes that it is in or approaching the fully closed position.

17) The word "record" applies to any form of permanent storage of information that permits

retrieval by any means.

18) For use of the term "transmitter" versus "converter," .

19) First-letter V, "vibration or mechanical analysis," is intended to perform the duties in machinery monitoring that the letter A performs in more general analyses. Except for vibration, it is expected that the variable of interest will be defined outside the tagging bubble.

20) First-letter Y is intended for use when control or monitoring responses are eventdriven

as opposed to time- or time schedule-driven. The letter Y, in this position, can also signify presence or state.

21) Modifying-letter K, in combination with a first-letter such as L, T, or W, signifies a time rate of change of the measured or initiating variable. The variable WKIC, for instance, may represent a rate-of-weight-loss controller.

22) Succeeding-letter K is a user's option for designating a control station, while the succeeding-letter C is used for describing automatic or manual controllers.