MOTORISED VALVE ACTUATORS - SANTHIRAJ

1. MOTOR OPERATED
VALVE
MOV

2. Manual Operation
The following valves are all “manual” valves, requiring
the intervention of a human operator

3. Motor
Operated
Valve

4. 1. Looks much like a threaded fastener,
with its “threads” properly pitched to
engage with the teeth of the worm
wheel gear.
2. As the worm screw turns, it slowly
pushes or pulls the circumference of
the worm wheel, resulting in a large
gear ratio (i.e. many turns of the
screw are required to produce a single
turn of the wheel).
3. This slow-turning wheel moves a
sliding-stem valve by means of a
threaded shaft (another screw) or
4. Turn a rotary valve (e.g. butterfly,
ball, plug).
Motor Operated Valve

5. Motor Operated Valve

6. Motor Operated Valve

7. Motor
Operated
Valve

8. BALL VALVE

9. Ball Valve
Clutch
• Hand crank for manual operation, if the electric
motor (or the power provided to it) fails.
• A clutch mechanism to engage or disengage the
valve mechanism from the electric motor and the
hand wheel.
• This clutch “selects” either the motor or the hand
wheel as the prime mover for the valve, to avoid
having the hand wheel spin as the motor turns.
• Unless this lever is first moved to the “manual”
position, turning the hand wheel accomplishes
nothing.

10. Butterfly
Valve

11. Electric valve
actuator
coupled to a
large butterfly
valve.

12. Motor Operated Valve

13. Motor Operated Valve
•Forced Air
Cooled Motor
•S2-15 Duty

14. Motor Operated Valve
• Valve position Indicator
• limit switches to indicate when
the valve is fully shut and fully
open.
• For throttling services, 4-20 mA
position transmitter signal
output

15. Motor
Operated
Valve

16. MOV –
TERMINAL
BOX

17. MOV – WIRING

18. MOV –
MOUNTING

19. MOV –
Mounting on
Valve

20. Motor Operated Valve

21. •Open / close valves : Used to automate manual open and closed valves
some example given below
•Examples :
• Pump discharge and suction valves,
• Boiler feed water isolation valve,
• Drum vent valves
• Process steam line valves
• Inching valves : Used were some degree of control , gradual opening and
closing is required application example.
1.Re-flux lines
2.Boiler start up vent
3.Boiler IBD valves
4.Boiler main steam valves
• Precision flow valves : This is a precision inching valve the motor
operates in steps configured in controller example 10 % 15 % opening steps
. in precision flow valves , a continues control is enabled using proper
feedback from the field to the controller which is not usually found in other
motor operated valves .
MOV – Types

22. MOV – Inching
• More precise flow control compared
to the on/off valves.
• Facilitates gradual opening and
closing of the valve enabling some
degree of control over the flow.
• Examples include, reflux lines,
boiler start up vent, boiler IBD
valves, boiler main steam valves
etc.

23. MOV – O/C

24. MOV – Modulating
• Solid-state reversing starter with
fast-response remote control
circuits for rapid control.
• Positional control, optimized by
an electronic motor ‘brake'
feature.

26. Valve Actuator Functional Requirements -1/2
•Moving the valve closure member to the appropriate location.
A closure member is typically a plug, disc, or ball, and an actuator must have enough
force to move it even in difficult or undesirable conditions. Additionally, it has to be fitted
with the necessary controls to direct it.
•Holding the valve closure member in position.
Once in the desired position, a valve actuator must be able to hold it in place. In some
applications, such as throttling applications, this requires a robust spring or fluid power or
mechanical stiffness to keep the closure member securely in place.
•Seating the valve with enough torque to meet desired shutoff specifications.
Some types of valves may require special accessories for actuator sizing to sustain
enough torque to maintain closed positions.

27. •Having a failure mode.
A failure mode needs to occur in the event of a system failure. Depending on
the application, failure mode may be as-is, fully closed, or fully open.
•Having the proper rotational value.
Some valves require a certain amount of rotation, often 90 or 180 degrees.
Multi-ported valves often require more than 90 degrees of rotation, and
electric actuators are usually preferred for applications requiring rotation of
greater than 180 degrees, as they’re not limited in rotation mechanically.
•Providing the right operating speed.
The cycle speed of an actuator can be regulated with control circuit
elements, but cycle speeds less than half of the typical actuator cycle time
require careful valve selection. Specially prepared pneumatic actuators may
be required for high cycle speeds without risking damage to valve parts.
Valve Actuator Functional Requirements -2/2

31. • Electrical power is relatively inexpensive.
• Electrical actuators provide good accuracy on
valve movement and functioning, and it is
possible to monitor the opening percentage of
the valve.
• All control components are integrated into the
actuator, unlike pneumatic and hydraulic
actuators.
• Electrical actuators are cheaper, more compact,
and lighter than pneumatic and hydraulic
actuators.
MOV – Advantages

32. • Cannot maintain fail safe positions unless they are
combined with hydraulic power (electrical-hydraulic
actuators).
• Contain more complex and sensitive components
compared to pneumatic and hydraulic actuators.
• Not as economical as pneumatic or hydraulic actuators
above certain sizes.
• Require more certifications in hazard areas with explosive
fluids such as ATEX. ATEX stands for atmospheres
explosive, and it is a European Union Directive covers
equipment and protective systems for use in potentially
explosive atmosphere.
MOV – Disadvantages

34. Ladder Logic Diagrams-MOV
Instrumentation & Control Design

35. MOV – RDOL
Starter at
MCC

36. MOV –
Starter

37. Interface

38. Wiring Diagram

40. Ttotal = Tprocess + Tseat + Tpacking + Tmiscellaneous where
Ttotal = total toque required to open, close, or throttle valve
Tprocess = toque to overcome process pressure unbalance
Tpacking = toque required to overcome packing friction
Tseat = toque to provide correct seat load
Tmiscellaneous = toque to overcome special design factors, weight,
etc. Individual sizing equations to determine actuator size vary widely
Sizing Considerations

41. •Compatibility –
What power source is available? As discussed above, electric actuators, by nature, require
electricity to operate. If there is no readily available source of electricity, a pneumatic or hydraulic
valve actuator is the logical choice. Pneumatic actuators require an air supply between 40 and
120 psi. Higher pressures can be difficult to come by, and lower pressures will require a
diaphragm or piston with a larger diameter in order to achieve the necessary torque. Electric
actuators require a power supply of 110 VAC, but valve actuators can be purchased with DC and
AC motors in other sizes.
•Temperature Range
•Hazardous Areas
Application Requirements

42. The frequency of operation (or duty) impacts mechanical drive
durability and the robustness of the controller.
Obviously, valves that operate infrequently (such as isolating or
regulating duty valves) mean less wear and tear on mechanical
components and controls.
Other valves, however, such as modulating process valves,
operate on a near-constant or continuous basis, requiring a more
durable valve and actuator assembly.
Another general rule of thumb is based on the duty cycle:
•Isolation – the valve operates only a few times per day
•Regulating – 30 to 60 starts per hour
•Modulating – 600 to 1,800 starts per hour
Frequency of Movement

43. S1 Duty

44. Short time duty (S2)
Operation at constant load
during a given time, less
than that required to reach
thermal equilibrium,
followed by a rest and de-
energized period of
sufficient duration to re-
establish machine
temperatures within 2°C of
the coolant.

45. S3 Duty

46. Intermittent periodic duty with starting (S4)

47. Non periodic duty with load and speed variations
(S9)
• Load and speed vary periodically within the
permissible operating range.
• Frequent overloading may occur.