How to create a instrumentation loop drawing, say for instrument air vessel ?
Piping and Instrumentation (P&ID) diagram shows the several instrumentation loops connected with particular equipment.
P&ID shows signal path of instruments and gives overall picture of the connected loops in the system, whereas Instrument loop diagram gives clear idea of instrument connected with the system.
How-to Create Instrument Loop Diagram
- Instrument loop diagram (ILD) represents a connection from field instrument to Control Room.(vice versa)
- Instrument loop diagram is divided in to two basic sections. One is field side and other is Control Room side.(vice versa)
- Field side is again divided in to field area and Junction box.
- Control Room side is divided in to marshalling cabinet rear, Marshalling Cabinet Front.
Following data is required before starting drawing on paper for loop diagram
- Tag No of the instrument, JB Number, Terminal block and its termination number, Marshalling cabinet and Termination details. System card and I/O details.
Sample Instrumentation Loop Drawing (ILD)
- Pressure transmitter PIT-01 mounted field side it is connected by a single pair cable with red and black cable with red as (+) as 1 black (-) as 2.
- The cable connecting to junction box Tagged (JBA-01) is a single pair. Terminating in JB terminal block (at TB15, TB-16). The termination is square shaped cable connects at IN and OUT.
- Cable from JB is terminating in Marshalling cabinet (MXA-01) number and Terminal Block number (terminal number TB15, TB16).
- Instrument sleeve is grounded at marshalling cabinet only, need not at instrument or at junction box.
- Cable from Marshalling cabinet is connected to System I/O card.
- On the bottom right below, the details of organization name, drawn by, verified by, approved by can be seen.
R. Jagan Mohan Rao
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