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Instrument Abbreviations Used in Instrumentation Diagrams (P&IDs) III

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To further understand instrument abbreviations used in instrumentation and process diagrams, we have presented more examples of the common combinations of instrument abbreviations you may likely come across. They include abbreviations for switches and alarm devices, transmitters, solenoids, relays, computing devices, primary elements, test points, well or probe, viewing devices e.g glass, safety devices as well as final elements. 

The main objective of bringing many possible combinations of these process instruments is to drive home the understanding of how they are formed such that once you see them being used in a process or instrumentation diagram or even conceptual or flow diagrams, you will immediately be in a position to identify them and know what they are being used for.

First Letters
Initiating,  Measured, Variable
Switches & Alarm Devices*
Transmitters
Solenoids,
Relays,
Computing
Devices
Primary
Element
Test Point
Well or Probe
Viewing
Device,
Glass
Safety
Device
Final
Element
High**
Low
Comb
Recording
Indicating
Blind
A Analysis ASH ASL ASHL ART AIT AT AY AE AP AW

AV
B Burner/
Combustion
BSH BSL BSHL BRT BIT BT BY BE
BW BG
BZ
C User's Choice












D User's Choice












E Voltage ESH ESL ESHL ERT EIT ET EY EE



EZ
F Flow Rate FSH FSL FSHL FRT FIT FT FY FE FP
FG
FV
FQ Flow Quantity FQSH FQSL

FQIT FQT FQY FQE



FQV
FF Flow Ratio FFSH FFSL




FE




G User's Choice











H Hand

HS








HV
I Current ISH ISL ISHL IRT IIT IT IY IE


IZ
J Power JSH JSL JSHL JRT JIT JT JY JE



JV
K Time KSH KSL Cell KSHL KIT KT KY KE



KV
L Level LSH LSL LSHL LRT LIT LT LY LE
LWLG
LV
M User's Choice











N User's Choice










O User's Choice











P Pressure/
Vaccum
PSH PSL PSHL PRT PIT PT PY PE PP

PSV, PSEPV
PD Pressure,
Differential
PDSH PDSL
PDRT PDIT PDT PDY PE PP


PDV
Q Quantity QSH QSL QSHL QRT QIT QT
QE



QZ
R Radiation RSH RSL RSHL RRT RIT RT RY RE
RW

RZ
S Speed/
Frequency
SSH SSL SSHL SRT SIT ST SY SE



SV
T Temperature TSH TSL TSHL TRT TIT TT TY TE TP TW
TSE TV
TD Temperature,
Differential
TDSH TDSL
TDRT TDIT TDT TDY TE TP TW

TDV
U Multivaraible





UY




UV
V Vibration/
Machinery
Analysis
VSH VSL VSHL VRT VIT VT VY VE



VZ
W Weight/
Force
WSH WSL WSHL WRT WIT WT WY WE



WZ
WD Weight/
Force,
Differential
WDSH WDSL
WDRT WDIT WDT WDY WE



WDZ
X Unclassified











Y Event/State/
Presence
YSH YSL



YY YE



YZ
Z Position/
Dimension
ZSH ZSL ZSHL ZRT ZIT ZT ZY ZE



ZV
ZD Gauging/
Deviation
ZDSH ZDSL
ZDRT ZDIT ZDT ZDY ZDE



ZDV

*A, Alarm, the annuciating device, may be used in the same way as S, switch, the switching device.
** The letters H and L may be omitted in the undefined case.
The table above is a guide. It does not cover all possible combinations of  instrument abbreviations that one may encounter in the process industry.

Note that apart from the combinations above, there are some other possible combinations when it comes to instrument abbreviations. Some combinations which might not be common in your process plant are shown in the table below:

Instrument Abbreviation
Meaning or Designation Used to Qualify Instrument
FO
Restriction Orifice
FRK, HIK
Control Stations
FX
Accessories
TJR
Scanning Recorder
LLH
Pilot Light
PFR
Ratio
KQI
Running Time Indicator
QQI
Indicating Counter
WKIC
Rate-of-Weight-Loss Controller
HMS
Hand Momentary Switch




Instrument Abbreviations Used in Instrumentation Diagrams (P&IDs) II

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We have already seen how the letters A – Z are combined in instrumentation diagrams to give process instruments unique function and identification in Instrument Abbreviations Used in Instrumentation Diagrams (P&IDs). Since the subject of process instrumentation diagrams is versatile and at the heart of understanding key industrial processes, we present further examples of instrument abbreviations as defined in the ISA 5.1 standard for symbols used in P&IDs. In the table presented below, we have:
(a) A column for the first letter denoting the process variable
(b) A second column denoting the initiating or measured variable
(c) A third column for controllers of various degrees – recording, indicating, blind (denotes a controller without a modifying function such as recording or indicating) and self-actuated control valves designed to regulate diverse process variables
(d) A fourth column for readout devices which can either be recording or indicating as the case maybe.

The table for instrument abbreviations shows many possible combinations for any kind of instrument measuring the defined variables as denoted by the first letter in the first column.

First Letter
Initiating or Measured Variable
Controllers
Read out Devices
Recording
Indicating
Blind
Self-Acutated Control Valves
Recording
Indicating
A Analysis ARC AIC AC
AR AI
B Burner/Combustion BRC BIC BC
BR BI
C User's Choice





D User's Choice





E Voltage ERC EIC EC
ER EI
F Flow Rate FRC FIC FC FCV, FICV FR FI
FQ Flow Quantity FQRC FQIC

FQR FQI
FF Flow Ratio FFRC FFIC FFC
FFR FFI
G User's Choice





H Hand
HIC HC


I CurrentIRC IIC

IR II
J Power JRC JIC

JR JI
K Time KRC KIC KC KCV KR KI
L Level LRC LIC LC LCV LR LI
M User's Choice





N User's Choice





O User's Choice





P Pressure/Vacuum PRC PIC PC PCV PR PI
PD Pressure, Differential PDRC PDIC PDC PDCV PDR PDI
Q Quantity QRC QIC

QR QI
R Radiation RRC RIC RC
RR RI
S Speed/Frequency SRC SIC SC SCV SR SI
T Temperature TRC TIC TC TCV TR TI
TD Temperature, Differential TDRC TDIC TDC TDCV TDR TDI
U Multivariable





V Vibration/Machinery Analysis





W Weight/Force WRC WIC WC WCV WR WI
WD Weight/Force, Differential WDRC WDIC WDC WDCV WDR WDI
X Unclassified Cell Cell Cell Cell Cell Cell
Y Event/State/Presence
YIC YC
YR YI
Z Position/Dimension ZRC ZIC ZC ZCV ZR ZI
ZD Gauging/Deviation ZDRC ZDIC ZDC ZDCV ZDR ZDI




Common Symbols Used in Pneumatic Systems and Instrumentations

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Pneumatic Systems are still popular in older plants and even in modern plants where their use is inevitable. Pneumatic diagrams representing pneumatic systems have defined ways they are represented. They are commonly represented with symbols. These symbols needs to be understood before you can correctly interpret pneumatic drawings and diagrams. These common symbols are shown below:

Pneumatic Directional Control Valves Symbols
Symbols of Directional Control Valves (Photo Credit: AutomationDirect.com)




















Symbols of Simple Pneumatic Valves
Pneumatic Valve Symbols (Photo Credit: AutomationDirect.com)















Line Symbols Used in Pneumatic Drawings
Line Symbols in Pneumatic Symbols (Photo Credit: AutomationDirect.com)



















Symbols of Common Equipment Used in Pneumatic Drawings and Systems
Symbols of Common Pneumatic Equipment. (Photo Credit: AutomationDirect.com)

Common Actuator Symbols Used in Pneumatic Drawings
Actuator Symbols (Photo Credit: AutomationDirect.com)