Page 44 - APPLIED PROCESS DESIGN FOR CHEMICAL AND PETROCHEMICAL PLANTS, Volume 1, 3rd Edition

Process Planning, Scheduling and Flowsheet Design 29

Table 1-4
Instrumentation Nomenclature-Complete General Identification*

I
MODIFICATION OF ISA STANDARDS
FIRST LETTER SECOND AND THIRD LETTERS
Controlling Devices Measuring Alarm Devices
Devices
* Process Cl Cl .,
cu
u
u"C ..
VC!riable ·.E ] I "' cu .s ·- c
>
'6�
�o·.:
0
Cl
tD
tn
or .s .s c� c CIJ � .s Cl Cl tD C:, C
..
u"C
c
c
c
.2 >
·- c
... c
Actuation "'CJ '6 ·- c Ill <c >, "C '6 i '6 "C ·- >,; ... -� �
"C·-
...
c-
c- c cu
cu
• _ al
EE qj .. "'
....
c�
() u c- > z> Gi 0 .!:! 0 .!:! ·-al ... _ "' "'> cu
u -=o 0 u "C u "C 0 ·- cu c '-..a
c
cu
cu
c
0,
a� .s z > qj If) "' .s "' .s z ll-W � 5-Eo
If)
RC IC c CV v sv R I RA IA A E w G
Flow F FRC FIC FV FR Fl FRA FIA FA FE FG
Level L LRC UC LC LCV LV LR LI LRA LIA LA LE LG
Pressure p PRC PIC PC PCV PV PSV PR Pl PRA PIA PA PE
Speed s SRC SIC SC scv ssv SR SI SRA SIA SA
f--.
Weight w WRC WJC WR WI WRA WIA WE
Analysis A ARC AIC AC ACY ASV AR Al ARA AIA AA AE
Hand H HIC HC HCV
Temperature T TRC TIC TC TCV TV TSV TR Tl TRA TIA TA TE TW
I , pe 101 x XRC XIC xc xcv xsv XR XI XRA XIA XA XE I
-
NOTE: Blank spaces are impossible or improbable combinations.
I
By permission, D.J. Oriolo, 0. & G.Jour., Nov. 17, 1958; Also see ISA Stds. Latest edition.
Thermocouples carry the same designation as the sheet, but here again the use of detail which does not con-
recorder or indicator to which they are connected. Sequen- tribute to the communication function of the sheets is
tial point numbers are indicated thus (see Table 1-4): avoided. Such detail can be time consuming when consid-
ered over the entire set of sheets for a process. Figures 1-8
RTM-&---4, Thermocouple connected to point No. 4 and 1-9 are typical of reasonably good presentation with-
RTM instrument No. 6. Also see Figure out unnecessary detail. Such specifications as height of a
1-10.
seal leg, locked open valve, or other information not sum-
Additional symbols include: marized elsewhere must be recorded on the flowsheets.
PG-6, Pressure Gage No. 6 connected in the field
on some item of equipment. If panel board
mounted, it becomes·-6B. Working Schedules
LTA-1, Low Temperature Alarm No. 1
HTA-1, High Temperature Alarm No. 1
LPA-2, Low Pressure Alarm No. 2 As a direct companion of the completed flowsheet, the
HPA-2, High Pressure Alarm No. 2 line schedule sheet transmits the process and mechani-
LLA-6, Low Level Alarm No. 6 cally necessary details for proper interpretation of the
HLA-8, High Level Alarm No. 8 piping aspects of the Ilowsheet (see Figures l-24A, B, C,
PG- . Push Button D). These schedules are initialed by the process engineer
to further explain the requirements of the process as
Process flowsheets do not normally show companion shown on the Ilowsheets, They are often and perhaps usu-
flanges for valves unless these serve as blinds or for orifice ally cooperatively completed by other engineers, particu-
plates. This detail is sometimes shown on the piping flow- larly the piping, mechanical and instrumentation groups.