Final control elements are devices like valves and pumps that adjust the manipulated variable to control process parameters. Common parameters include pressure, flow, level, and temperature. Control valves have components like actuators, bodies, and trim. Actuators provide the force and include pneumatic, hydraulic, and electric types. Valves types are ball, butterfly, gate, and globe valves. Positioners maintain the correct valve position. Control valves can experience issues like leaks, sticking, or nonlinear flow. Troubleshooting addresses problems like deadband, overshoot, sizing errors, and nonlinear characteristics.

1. Prepared by,
Mujtaba Moosawi
S.Inst Technician

2. ASSESSMENT
 Mention 3 final control elements.
 What is the function of final control element?
 What are the types of actuators?
 What are the types of valves?

3. MAIN POINTS
Final Control Element:
 What is a final control element?
 Process Parameters
 Control valve components.
Actuators & Valves:
 Types of actuators
 Types of valves
 Valve Accessories.
Troubleshooting:
 Valve characteristics
 Control valves Challenges
 Control Valves Troubleshooting.

4. FINAL CONTROL ELEMENT
the final control element is a device which
adjust the value of the manipulated
variable by controlling flow of the control
agent.
The mechanism for affecting this change may
be a valve, pump, transformer, motor, variable
speed drive, etc.

5. PROCESS PARAMETERS
Parameters normally measured and controlled in a
process industry are: -
 Pressure
 Flow
 Level
 Temperature
 Speed
 pH, conductivity
 Composition
 Density
 BS & W
 Dew point
 Oxygen content (injection water), etc.

6. 12PI-001 12PC-001
12PCV-001
Transmitter
Control Room
DCS
Control
Valve
Control Room
DCS
15LI-003
15LC-003
15LCV-003
Transmitter

7. CONTROL VALVE MAIN COMPONENTS
Actuator
Valve body
Control Valve

8. CONTROL VALVE COMPONENTS

9. CONTROL VALVE COMPONENTS

10. ACTUATORS
- actuator provides the
force that actuates the
valve.
- determine the flowrate
of an agent through the
valve.
- Means used to operate
the actuator may be
• mechanical,
• pneumatic,
• electrical,
• hydraulic, or
• a combination of two of
these methods.

11. TYPES OF ACTUATORS
Air to close valve
Air to open valve

12. A CONTROL VALVE WHICH OPERATES FROM A HIGH PRESSURE TO LOW
PRESSURE, WE PREFER AN AIR FAIL TO CLOSE VALVE TO AVOID OVER
PRESSURIZING OF THE DOWN STREAM FACILITIES. THE LEVEL CONTROL
VALVE OF THE BULK SEPARATORS WILL BE AN AIR FAIL CLOSE VALVE.
THIS IS TO PROTECT SURGE TANK FROM OVER PRESSURIZING IN CASE
OF A FAILURE OF THE SEPARATOR LCV.
Bulk separator
Surge tankLCV
PRC
Gas to flare
Air fail close valve
Air fail open valve
LC
PC
Gas to Compressor

13. VALVE TYPES
 Ball Valve
 Butterfly Valve
 Gate Valve
 Globe Valve

14. BALL VALVE
Sphere with a port in a
housing, rotate to expose
channel.
 Applications: Flow control,
pressure control, shutoff,
corrosive fluids, liquids,
gases, high temp.
 Advantages – low
pressure drop, low leakage,
small, rapid opening
 Disadvantages – seat can
wear if used for throttling,
quick open may cause
hammer

15. BUTTERFLY VALVE
rotating disk on a shaft, in
a housing.
Low pressure, large
diameter lines where
leakage is unimportant
Advantages – low
pressure drop, small and
light weight
Disadvantages – high
leakage, high actuation
forces so limited to low
pressures

16. GATE VALVE
Sliding disk, perpendicular to
flow
Applications: Stop valves,
(not throttling), high
pressure and temp, not for
slurries, viscous fluids
Advantages – low pressure
drop when fully open, tight
seal when closed, free of
contamination buildup
Disadvantages – vibration
when partially open, slow
response and large
actuating force

17. GLOBE VALVE
plug moved perpendicular to
flow and closes on a ring seat
Throttling, general purpose
flow control valve
Advantages – faster than
gate, seat less wear and tear,
high pressure drop for
pressure control
Disadvantage high pressure
drop, require considerable
power to operate (gears and
levers), heavy

18. ANIMATION

19. VALVES’ SYMBOLS

20. VALVE ACCESSORIES
Control
Room
800 KPa
400 KPa

21. POSITIONER
Positioner
Input from I/P
supply air
output to valve
- keeps the valve at the
correct operating position.
- Boosts the pressure and
volume of the air coming out
from the I/P converter
before given to the valve.
- Possible to reverse the
output of the I/P before
given to the valve
diaphragm.

22. VALVE CHARACTERISTICS
 Classified by relationship
between the valve stem
position and the flow rate
 Quick Opening
 Used for full ON/full OFF
 Small motion of the stem, resulted
in maximum possible flow rate
 Linear
 Flow rate varies linearly with stem
position
 Equal Percentage
 Percentage change in stem position
equal percentage change in flow rate

23. OTHER VALVES
 Motor operated valve
 Emergency Shut down
valve
 Solenoid valve

24. CONTROL VALVES ISSUES
 Actuator:
- Diaphragm rupture
- Gland Packing
damage
- Regulator pressure
setting
 Valve:
 Passing
 Leaking
 Not opening/closing

25. CONTROL VALVES TROUBLESHOOTING
 Four problems with control valves are found at a
high frequency in poorly performing control loops.
These are:
- Dead band
- Positioner overshoot
- Incorrect valve sizing
- Nonlinear flow characteristic

26. CONCLUSION
Final Control Element:
 What is a final control element?
 Process Parameters
 Control valve components.
Actuators & Valves:
 Types of actuators
 Types of valves
 Valve Accessories.
Troubleshooting:
 Valve characteristics
 Control valves Challenges
 Control Valves Troubleshooting.

27. Q
Many thanks,
Mujtaba Moosawi