Instrument Identification Number or Tag Number is an alphanumeric codes that provides specific information about an instrument or its function.
Note: A typical tag number contains two types of information, The Function Identification and Loop Identification.
FUNCTION IDENTIFICATION
A functional identification is a series of letters or letter code that identifies the function of instrument.
The first letter identifies the measured of initiating variable.
The succeeding letter designate one or more readout or passive function and/ or output function.
Example 1: Function Identifier/ Typical Tag Number
F I C A – 101 (what does FICA means?)
F = flow initiating variables
I = indicating function
C = control function
A = alarm function
LOOP IDENTIFICATION:
Loop Identification Numbers indicates the loop in which the instrument belongs. The loop identification number is assigned to all instruments included in the loop regardless of their function or location.
TAG PREFIX AND SUFFIX:
A prefix maybe added to the tag no. to denote area or plant location.
A suffix maybe added to the loop number in loops that contain more than one instrument with the same functional identification.
LOOP NUMBERING:
Loop numbering maybe parallel or serial. With parallel numbering, a numerical sequence is started for each new first letter. Ex. TIC-100, FRC-100, LIC-100
Serial numbering uses a single sequence of numbers for a project or for large sections of project regardless of the first letter of the loop identification. Ex. TIC-100, FRC-101, LIC-102
Roldan B. Sebastian 