2. 2
Introduction
INSTRUMENTATION - VALVES
What is a valve?
Any device for closing or modifying the
passage through a pipe, outlet, inlet or the
like, in order to stop, allow, or control the
flow of a fluid media.
…..continued
3. 3
Introduction
INSTRUMENTATION - VALVES
This presentation explains:
1- The main 9 types of valves used in the
Petrochemical industry. Such as; Globe Valve,
Butterfly Valve, Diaphragm Valve, Gate Valve,
etc.
2- What is an Actuator:
Air, fluid-powered or electrically powered device
that supplies force and motion to a VALVE
CLOSURE MEMBER. Called an Actuator
…..continued
4. 4
Introduction
INSTRUMENTATION - VALVES
3- Control Valves:
Process plants consist of hundreds, or even
thousands of control loops, all networked
together to produce a product to be offered for
sale. Each of these control loops is designed to
keep some important process variable such as
pressure, flow, level, temperature etc. within a
required operating range to ensure the quality of
the end product. Here the control valves job come
and that is the importance of control valves.
…..continued
6. 6
Agenda
Day 34 Introduction to control valves
Day 35 Types of Valves and their operation
Day 36
Advantages, disadvantages, selection
and specifications for valves
Day 37 Actuators, Solenoids and Positioners
Day 38 Revision & Exam
INSTRUMENTATION - VALVES
7. 7
• State the three main reasons for
controlling fluids.
• Identify different types of control valve.
• Know the specific uses of various
valves.
• Select appropriate valves for specific
tasks.
Learning Objectives
INSTRUMENTATION - VALVES
The trainee will:
…..continued
8. 8
• Understand the valve specification and
selection requirements.
• State the advantages and disadvantages
of a variety of different valves.
• State the purpose and use of actuators.
• State the purpose and use of
positioners.
Learning Objectives
INSTRUMENTATION - VALVES
The trainee will:
9. 9
What is a Control Valve?
INSTRUMENTATION - VALVES
Valves are the most common components in process piping systems.
They are the main method of fluid (liquid & gas) control for:-
Flow
Pressure
Direction
…..continued
10. 10
INSTRUMENTATION - VALVES
> Valves may be required to operate continuously e.g. control valves.
> They may be operated intermittently e.g. isolation / stop valves.
> They may be installed to operate rarely e.g. safety valves.
> A valve can be a very simple, low cost item or it may be a very
complicated, expensive item.
11. 11
INSTRUMENTATION - VALVES
1. Valves are selected for their:-
> Ability to throttle flow
> Lack of turbulence or resistance to flow when fully open
> Quick opening and closing mechanism
> Tight shut off
> Ability to allow flow in one direction only
> Opening at a preset pressure for pressure control
> Ability to handle abrasive substance without rapid wear.
12. 12
INSTRUMENTATION - VALVES
2. Flow Regulation / Throttle Valves
Many applications require the flow of the fluid to be regulated
(throttled) at some fixed level between zero and maximum
flow limits.
Valves used for this job include globe valves, needle valves &
butterfly valves.
13. 13
3. Pressure Regulation
> In many applications, especially with gases, there is a need
to reduce the supply pressure to a set fixed value.
> It may also be necessary to maintain this reduced pressure
over a range of fluid flow conditions.
> The pressure regulator valve (which has a globe valve
design) is used for this job.
INSTRUMENTATION - VALVES
14. 14
4. Non-Return or Check Valves
> In some circumstances it is important to prevent
reversed fluid flow.
> The type of valve used for this job is called a non-
return-valve (NRV) or check valve.
> Three main valve types are used for this job:
Lift Check valve
Swing Check valve
Ball Check valve
INSTRUMENTATION - VALVES
15. 15
5. Pressure Relief Valves
> Pressure Relief Valves (PRV) are used in liquid service
applications to relieve excess pressure in the system.
> All closed vessels where pressure could build up are
protected by a Pressure Relief Valve.
> An important part of the relief valve installation is the routing
of the relieved fluid.
> Normally relieved fluid is returned to a service tank or
unpressurised part of the system.
> Return lines must always be kept open.
INSTRUMENTATION - VALVES
16. 16
6. Pressure Safety Valves
> Pressure Safety Valves (PSV) are used in gas service
applications where too much pressure in the system
can cause damage or a safety risk.
> Valves used for safety applications require regular
inspections to check the settings and the operation.
> The gas released from a PSV normally goes to the
flare.
INSTRUMENTATION -VALVES
17. 17
INSTRUMENTATION - VALVES
7. Isolation/Stop Valves
Valves used for this job include gate valves, globe valves,
ball valves, plug valves & diaphragm valves.
The isolation of the downstream system from the upstream
system by use of an isolation or stop valve is a very
important function.
The main requirements of these valves are:-
> tight shut off when closed
> minimum restriction to flow when open
18. 18
8. Valve Specifications and Selection
INSTRUMENTATION -VALVES
Specifications to consider when selecting valves are;-
> Diameter
> Working pressure
> Operating temperature
> Type of fluid
> Valve material i.e. brass, bronze, copper, cast
iron, ductile iron, stainless steel, plastics
Continued…….
19. 19
9. Valve Specifications and Selection
INSTRUMENTATION -VALVES
> End configuration i.e. threaded, socket weld, butt
weld, push on, soldered ends, clamp, grooved,
flangeless, lugged, mechanical joint or flanged
> Valve actuation method i.e. electric, pneumatic,
hydraulic or manual.
> Seat features i.e. metal to metal, o-ring, soft seat.
Continued…….
20. 20
10. Valve Specifications and Selection (continued)
INSTRUMENTATION -VALVES
> Valve class i.e. class IV, V or VI, ANSI standards,
MSS specifications, UL listings, ASME standards,
and federal specification WW-V-35C.
> Applications i.e. petrochemical, chemicals,
general purpose, different oils or fuels, sanitary,
wastewater, water, fire service, refrigeration,
laboratory, medical or cryogenic.
21. 21
What three things can a valve control ?
1. Pressure
2. Flow
3. Direction
Flash Card
INSTRUMENTATION - VALVES
22. 22
Name three valves that can be used for throttling flow ?
1 Needle valve
2 Globe valve
3 Butterfly valve
Flash Card
INSTRUMENTATION - VALVES
23. 23
Name three valves that can prevent non return of a
fluid down a pipeline?
1. Lift Check Valve
2. Swing Check Valve
3. Ball Check Valve
Flash Card
INSTRUMENTATION - VALVES
24. 24
Which one of the following valves is NOT a
stop/isolation valve?
1. Gate
2. Plug
3. Ball
4. Diaphragm
5. Globe
6. Needle
The Needle Valve is NOT a stop or isolation valve
Flash Card
INSTRUMENTATION - VALVES
25. 25
Name one valve that rarely operates when in
normal service?
Pressure Relief Valve
Flash Card
INSTRUMENTATION - VALVES
26. 26
State ten considerations when selecting a valve for
use?
1. Diameter
2. Pressure
3. Temperature
4. Type of fluid
5. Valve material
6. End configuration
7. Actuation
8. Seating
9. Class of valve
10. Application
Flash Card
INSTRUMENTATION - VALVES
29. 29
PLUG VALVE
Advantages:
Cheap
Offer low resistance to flow when fully open
Open and close quickly
Give a tight seal with pressures up to 200 bar
Disadvantages:
The plug valve is mainly an on/off valve and is not
particularly good for precise regulation
Despite lubrication, the plug valve has a tendency to bind
(stick)
INSTRUMENTATION - VALVES
TYPES OF VALVES
33. 33
BALL VALVE
Advantages:
Low pressure drop when open
Can be used for gas, liquids or slurries
Open and close quickly and easily
Require no lubrication
Are suitable for handling corrosive fluids
INSTRUMENTATION VALVES
TYPES OF VALVES
34. 34
BALL VALVE
Disadvantages:
Standard Ball Valve not suitable for
regulating flow
Not suitable for tight shut-off
Can be damaged & jammed by solids
INSTRUMENTATION VALVES
TYPES OF VALVES
35. 35
GATE VALVE
> Gate valves are probably the most widely used
valve type in the Petrochemical / refining
industry
> There are two main types of gate valve:
1. Rising stem
2. Non-rising stem
INSTRUMENTATION - VALVES
TYPES OF VALVES
39. 39
GATE VALVE
(RISING STEM)
In the rising stem gate valve
the threaded (screwed) part
of the stem is outside of the
valve.
The position of the rising
stem shows if the valve is
open or closed.
INSTRUMENTATION - VALVES
TYPES OF VALVES
41. 41
GATE VALVE
(NON-RISING STEM)
In the non-rising stem
gate valve the threaded
(screwed) part of the
stem is inside the valve.
It is difficult to see if the
valve is open or closed.
INSTRUMENTATION - VALVES
TYPES OF VALVES
43. 43
GATE VALVE
Advantages:
Low pressure drop when fully open
Offer reasonable flow-rate regulation
Cheap to manufacture
Very robust (strong) construction
Disadvantages:
Sediment or dirt may stop the gate closing fully
The base of the gate is liable to wear by erosion if operated
partly open
The gate valve is difficult to operate when opening or
closing against fluids at a very high pressure.
INSTRUMENTATION - VALVES
TYPES OF VALVES
47. 47
GLOBE VALVE
Advantages:
Good flow regulation
Positive shut-off
Can be used in high pressure systems where positive shut-
off is essential for safe operation
Disadvantages:
x high pressure drop even when the valve is fully open
x The valve seats can be damaged and jammed by solids
INSTRUMENTATION - VALVES
TYPES OF VALVES
49. 49
DIAPHRAGM VALVE
Advantages:
Fairly cheap and easy to make
Provide good flow regulation
Maximum wear is located at the diaphragm which is easy
to change
Disadvantages:
X Cannot be used at very high pressures, due to the
weakness of the diaphragm
X They produce a pressure drop when open
INSTRUMENTATION - VALVES
TYPES OF VALVES
50. 50
NEEDLE VALVE
Needle valves are used to
give fine, accurate control of
flow.
The 'needle' shaped closing
element is long and comes
to a point.
The seat is also very small.
The stem threads are close
together (a fine thread)
which makes very small
adjustment of the flow
possible.
INSTRUMENTATION - VALVES
TYPES OF VALVES
52. 52
NEEDLE VALVE
Advantages:
Suitable for regulating flow
Fine control in small diameter piping
Tight shut-off
Disadvantages:
X Only for clean fluids
X Can only be used with low flows rates
X High pressure drop when open
INSTRUMENTATION - VALVES
TYPES OF VALVES
56. 56
BUTTERFLY VALVE
Advantages:
The valve can be part open in any position from fully closed
to fully opened.
Fast operation - the valve moves from full close to full open
in a quarter of a turn
The handle shows if the valve is open or closed.
They can receive flow from both sides.
Disadvantages:
X Can only be used with low flows rates
X Not suitable for tight shut-off
INSTRUMENTATION - VALVES
TYPES OF VALVES
57. 57
NON RETURN (NRV) or CHECK VALVES
Non Return Valves (NRV) and Check Valves only allow flow in one
direction.
There are several different designs.
The following slides show the three main types:
> BALL CHECK VALVE
> SWING CHECK VALVE
> LIFT CHECK VALVE
INSTRUMENTATION - VALVES
TYPES OF VALVES
63. 63
PRESSURE RELIEF VALVE (PRV)
(Review)
> Pressure Relief Valves (PRV) are used in process
applications to relieve excess pressure in the system.
> All closed vessels where pressure could build up are
protected by a Pressure Relief Valve.
> An important part of the relief valve installation is the routing
of the relieved fluid – Normally relieved fluid is returned to a
service tank or unpressurised part of the system.
> Return lines must always be kept open.
INSTRUMENTATION - VALVES
TYPES OF VALVES
68. 68
PRESSURE SAFETY VALVE (PSV)
(Review)
> Pressure Safety Valves (PSV) are used in gas service
applications where too much pressure in the system can
cause damage or a safety risk.
> Valves used for safety applications require regular
inspections to check the settings and the operation.
> The gas released from a PSV normally goes to the flare.
INSTRUMENTATION - VALVES
TYPES OF VALVES
71. 71
A bursting disc is a
non re-usable device
that is designed to
burst or rupture at a set
pressure, thus
protecting process
equipment from high
pressure or vacuum.
PRESSURE SAFETY – BURSTING DISCS
INSTRUMENTATION - VALVES
TYPES OF VALVES
75. 75
INSTRUMENTATION - VALVES
SOLENOID VALVES
Solenoid controlled valves are the most frequently used in
controlling fluids.
The task of a solenoid valve is to:-
> Shut off flow
> Release fluids
> Dose
> Distribute fluids
> Allow mixing of fluids
TYPES OF VALVES
76. 76
INSTRUMENTATION - VALVES
SOLENOID VALVES
Advantages
High reliability
Fast, safe switching
Long service life
Low control power
Compact design
Disadvantage
x Requires an electrical supply
TYPES OF VALVES
77. 77
INSTRUMENTATION - VALVES
This solenoid valve is an
electro-mechanical valve
(used with liquids or
gases) controlled by
operating an electrical
current through a
solenoid (coil of wire).
SOLENOID VALVES
TYPES OF VALVES
78. 78
Types of Solenoid Valve
> Electromechanical solenoid
An electromagnetic inductive coil wound
round a movable steel armature moves to
provide a mechanical force to the valve.
INSTRUMENTATION - VALVES
SOLENOID VALVES
TYPES OF VALVES
79. 79
> Pneumatic solenoid
These are switches which route air to a
pneumatic device (actuator). The moveable
solenoid channels the gas to an appropriate
port.
> Hydraulic solenoid
Similar to pneumatic solenoids except they
control the flow of hydraulic fluid.
INSTRUMENTATION - VALVES
SOLENOID VALVES
TYPES OF VALVES
80. 80
INSTRUMENTATION - VALVES
ACTUATORS
System actuators use
hydraulic, electronic and
pneumatic input signals to
help activate process control
equipment. Actuators are a
type of transducer or device
that turns signals into physical
motion.
TYPES OF VALVES
Electronic Actuator
81. 81
INSTRUMENTATION - VALVES
MANUAL ACTUATOR
This type of actuator
does not require an
outside power source.
They use a hand wheel
or lever to drive a series
of gears.
TYPES OF VALVES
82. 82
INSTRUMENTATION - VALVES
PNEUMATIC VALVE
ACTUATOR
Pneumatic valve
actuators adjust valve
position by converting air
pressure into linear or
rotary motion.
TYPES OF VALVES
83. 83
INSTRUMENTATION - VALVES
PNEUMATIC VALVE
POSITIONER
Valve positioners
compare a control
signal to a valve
actuator’s position and
move the actuator. They
are used with both
linear valves and rotary
valves.
TYPES OF VALVES
84. 84
Name eight types of valves used in the Petrochemical
industry?
1. Pressure Relief Valve
2. Globe Valve
3. Butterfly Valve
4. Diaphragm Valve
5. Gate Valve
6. Ball Valve
7. Plug valve
8. Needle Valve
Flash Card
INSTRUMENTATION - VALVES
85. 85
Control Valve Operation.
Complete the following statement:-
1. Some advantages of using a Solenoid Valve
are:-
high ______________ , fast and _______
switching,
________ service life,
_____ control power,
___________ design,
Flash Card
INSTRUMENTATION - VALVES
reliability safe
long
low
compact
86. 86
Control Valve Operation.
Complete the following statement:-
1. Actuators are a type of transducer that turns
____________ into ____________ motion.
Flash Card
INSTRUMENTATION - VALVES
signals physical
87. 87
Flash Card
INSTRUMENTATION - VALVES
Name these valves.
Ball Valve
Butterfly Valve
Safety Relief Valve
Control
Valve
1 2
3
4
88. 88
Flash Card
INSTRUMENTATION - VALVES
1. What does PRV stand for?
Pressure Relief Valve
2. Where are PRV’s used ?
Closed vessels e.g. Boiler
89. 89
Flash Card
INSTRUMENTATION - VALVES
1. What does SRV stand for?
Safety Relief Valve
2. What are SRV’s used for ?
Relieve excess pressure and eliminate
the risk of damage.
90. 90
Flash Card
INSTRUMENTATION - VALVES
What is the main reason for fitting ball
check valves, swing check valves and lift
check valves ?
To provide a one-way flow and non-return of
fluid up the pipeline.
91. 91
Summary
• Function of Control valves
- flow, pressure and direction
• Valve specifications and selection
INSTRUMENTATION - VALVES
- Swing check valve
- Lift check valve
- Pressure reducing valve
- Pressure safety valve
- Bursting discs
- Solenoid valves
- Actuators
- Valve positioners
- Plug valve
- Ball valve
- Gate valve
- Globe valve
- Diaphragm
- Needle valve
- Butterfly valve
- Ball check valve
• Types of Valves, operation, advantages and disadvantages
• Solenoid valves, actuators and positioners