valve functions and types

1. Valves
functions and types
Shivaji Choudhury

2. Valves
 Many different types of valves are
used in a industrial plants to perform
various functions.
 Valves are used for on-off service,
modulating/throttling service, to
protect components against
overpressure, and to prevent
backflow from occurring.

3. Types of Valves
In general, valves may be categorized
within the following four groups :
1. Isolation Valves:
2. Control Valves:
3. Pressure Relief Valves:
4. Check valves

4. Valve functions
And types
Isolation
Valve
Control
valve
Check
valve
Pressure
Relief valve
Gate
globe
butterfly
ball
plug
diaphragm
globe
butterfly
Ball included
Cam type
Self contained
regulators
Swing check
Lift check
Tilting disk
check
Double D
check
Silent
check
Stop
check
Self acting
relief
Self acting
safety
Power
Optd relief
VALVE FUNCTIONS AND TYPES

5. Isolation Valves
 Used for on-off service (including
throttled position) with local or
remote actuation. Depending on the
particular application and operating
conditions,

6. Isolation Valves
 Isolation valves, both manual and power
operated, are typically used to isolate a
system component or a section of the
piping system for:
 Maintenance
 Testing (for example, hydrostatic,
pneumatic, operational, or functional)
 Diversion of flow from one system
component or piping section to another to
facilitate load adjustments .

7. Gate valve- isolation functions
 A gate valve, also
known as a sluice
valve, is a valve that
opens by lifting a round
or rectangular
gate/wedge out of the
path of the fluid.
 The distinct feature of a
gate valve is the sealing
surfaces between the
gate and seats are
planar, so gate valves
are often used when a
straight-line flow of fluid
and minimum restric-tion
is desired.

8. GLOBE VALVES—ISOLATION FUNCTION
 Globe valves are normally
metal or hard-seated, but
they can be furnished with
resilient disc inserts or
seats that are suited for
compressed air,
compressed gas, or fluids
that contain small particles
of foreign material.

9. BUTTERFLY VALVES—ISOLATION
FUNCTION
Butterfly valves are
high pressure
recovery valves
(also called high
capacity and high
area ratio valves)
with relatively
small overall
pressure drop in
the fully open
position as
compared to globe
valves.

10. BALL VALVES—ISOLATION FUNCTION
 Ball valves are quarter-turn
valves, occupy less
vertical space than rising
stem valves,and can be
installed in almost any
orientation.
 Ball valves are bi-directional
except for
some eccentric or
wedged ball designs.

11. PLUG VALVES- isolation functions
 Like the ball valve,
the plug valve is a
quarter-turn valve.
It uses a
cylindrical or
conical-shaped
closure member
instead of the
spherical shape
used in the ball
valve.

12. DIAPHRAGM VALVES—ISOLATION
FUNCTION
 The diaphragm valve is
comprised of a bonnet,
body, and flexible-sealing
member. The flexible
sealing member is
available in a variety of
materials such as Buna-N,
Viton, TFE, polyethylene,
or neoprene.
 This valve is particularly
suited for corrosive fluid,
slurries, scale-forming
service, and where zero
stem leakage is
mandatory

13. Control Valves
 Used for modulating or throttling service.
Their operation is automatic in response to
continuous monitoring of some parameter
in the controlled system.
 In general, control valves require no
manual operator action.
 A control valve functions as a variable
resistance in a pipeline.

14. Control Valves
 A modulating control
valve is a device used
to automatically
throttle process fluids
as required by changes
in a variable such as
pressure, temperature,
flow, or liquid level.

15. TOP GUIDED CONTROL VALVE
Top-guided, single-ported
valves may be
used for tight shutoff
applications; however,
because these valves
are unbalanced, they can
require more force from
the actuator to achieve
shutoff if the flow is
under the plug.

16. CAGE GUIDED VALVES
 Cage-guided valves
have a cylindrical plug
guided through a guide.
 The increased guiding
area is desirable for high
pressure drop, high
noise, and anticavitation
applications
 Unbalanced types can
provide a tight shutoff if
sufficient
 For balanced styles, the
plug is vented and the
process pressure
interacts with the top
and bottom side of the
plug.

17. DOUBLE SEATED CONTROL VALVE
 Double-seated control
valves are used to a
lot of industrial
applications due to
advantages of
reduction in actuator
force, a great flow
capacity and a deal of
slurry fluids.
 Double-seated valves
cannot provide the
same shutoff capability
as the single-ported
types.

18. Pressure Relief Valves
 Used to provide protection against
excessive pressure.
 The valve opens automatically when
pressure exceeds a preset level and closes
after pressure recedes below a preset level.
 Power-operated relief valves that open or
close in response to command signals are
also utilized.

19. Pressure relief valves

20. Check valves
 Used to allow flow in the normal flow
direction and to prevent flow in the
opposite flow direction (reverse flow).
 Check valves are typically opened
and closed by the flow forces.

21. Check Valves
 Check valves are self-actuated valves whose functions
include:
 Prevention of reverse flow
 Keeping lines full of fluid
 Prevention of loss of fluid when the system is not in
operation
 Prevention of reverse rotation of pumps
 Prevention of outflow of fluid from vessel
 Prevention of water column separation
 Check functions are generally satisfied by using lift,
swing, tilting disc, double disc, or silent (nozzle) check
valves.

22. Swing Check Valves
 Swing check valves are the
most common type of check
valve currently in plants due
to their simple design, low
pressure drop, economy,
reliable sealing, relative ease
of repair, and availability in a
wide range o f sizes.
 Swing check s consist of a
heavy disc suspended from a
hinge pin located above the f
low stream . They rely on
gravity force for clo sure. The
disc and h inge arm can be of
one piece o r two piece
construction .

23. Tilt Disc Check Valves
 Tilt check valves differ from the swing check
valves in that the hinge pin is located in the
flow stream , just above the center line of the
disc .
 The pressure loss, the flow rate at which the
disc fully opens, and the speed o f closure are
controlled primarily by the mass of the disc ,
the maximum angular rotation of disc, and the
amount that the hinge pin is offset from the
disc centerline.

24. Check valves
 Tilt Disc Check
Valves
 Lift check valve

25. Valve End Connections
Valves can be connected to pipes in
several ways, including:
 · Threads
 · Welding
 · Brazing
 · Soldering
 · Flanges and bolts
 · Flared or hub ends

26. Valve Symbols

27. THANKING YOU