1. Presentation by Clifford T. Johnson, PE, Control Systems Engineer
Loop Diagrams Chapter 7
Honeywell Chapter 3
Instrumentation
and Control Systems
Documentation
Loop Diagrams are most important for technicians
Presentation by Clifford T. Johnson, PE, Control Systems Engineer
Today
Instrumentation
ELC-213

2. Control Modes, Proportional. Reset & Rate
Assignment , Lab & video
Loop Diagrams
Control Modes, Proportional. Reset & Rate
Today
Assignment & Lab
ELC-213

3. ISA Definitions
These are excepts from the ISA Comprehensive Dictionary of
Instrumentation and Control
page 168 covering LOOP
ISA
Loop Definition
ELC-213

4. ICSD Chapter 7 Loop Diagrams
A better definition is:
A single stand alone device is NOT a loop
ICSD
Loop Diagrams
ELC-213

5. Instrument Loop Identification
Chapter 7, Pg. 141 details
The P&ID is where the actual loops are defined and receive their tagging and Loop numbers. The devices are then entered into the Instrument Index, the the specification sheet is created, the IOM is received and it would be at this point that the loop sheet can be developed
ICSD
Loop Identification
ELC-213

6. left up to the designer and engineer as they see fit
Loop Diagram Symbols
Instruments
ISA symbols are generally used to depict Instruments and control devices with the addition of terminals or ports
Other devices
Tanks, piping, etc are
left up to the designer and engineer as they see fit
ICSD
Loop Symbols
ELC-213

7. Energy Supply
Electrical, Pneumatic, and other requirements for operating the instrumentation and control devices must be clearly identified by the sources such as electrical breakers and air supplies. Not just what it is, but where is it coming from.
ICSD
Loop Energy
ELC-213

8. Instrument Action
ICSD
Instrument Action
ELC-213

9. Loop Diagram Field Area
ICSD
Loop area
ELC-213

10. Loop Diagram most common
ICSD
Loop Diagram
ELC-213

11. Loop Diagram complex
ICSD
Complex Diagram
ELC-213

12. You must show solenoid operation
Loop Diagram SIS
You must show solenoid operation
Download from Resources and Fill in Tags,
correct the symbols as necessary,
Show actual wiring with numbers and colors
and Fill in Title Block
Lab
SIS Loop Sheet
ELC-213

13. Loop Diagram for a fieldbus
ELC-213

14. Summary: Loop Diagrams
Next to the the P&ID, the Loop Diagram (or Sheet) is the most Important document for the Instrument Technician.
Do not let the contractor create the loop sheets. He does not have the proper experienced people to do a good job.
There are a few good Instrument Database software applications that make the job easier with fewer errors
Properly developed they will greatly assist the technician to troubleshoot a control problem.
Cliff T Johnson, PE, Control Systems Engineer
Instructor, CPCC, ELC-213 & PCI-162
Summary
Loop Diagram
ELC-213

15. Honeywell Chapter 3 Modes of Control
ELC-213

16. Honeywell Chapter 3 On-Off ( HVAC)
ELC-213

17. Honeywell Chapter 3 Propotional Band 100%
ELC-213

18. Honeywell Chapter 3 Propotional Band 20%
ELC-213

19. Honeywell Chapter 3 Propotional Band 200%
ELC-213

20. Honeywell Chapter 3 Reset (Integral) Action
ELC-213

21. Homework ASSIGNMENT Web Link
Find an example of a Loop Diagram on the web, web page LINK only to me, do NOT images or web pages
All s Subjects and File names must have
Subject:Your last Name-Subject-Assignment Date (AD)
subjects Ex: Johnson-LoopLink-AD
File name Ex: Johnson-Loop- AD.vsd
You will lose 1-3 points for incorrect subject
Subjects
Assignment
ELC-213

22. The End
End
Instrumentation
ELC-213