CONTROL VALVE

NAME : RESHVHIN RAJ JEEWA

DATE : 28/06/2016

Contents

1. WHAT IS CONTROL VALVE ?.....................................................................................32. CONTROL VALVE CLASSIFICATION.......................................................................43. LINEAR MOTION (CONTROL VALVE).....................................................................54. GLOBE VALVE - (LINEAR MOTION)........................................................................65. DIAPHRAGM VALVE - (LINEAR MOTION).............................................................96. PINCH VALVE - (LINEAR MOTION).......................................................................107. ROTARY MOTION.......................................................................................................118. BALL VALVE (ROTARY MOTION)............................................................................128. BUTTERFLY VALVE (ROTARY MOTION)...............................................................139. ACTUATORS................................................................................................................1410. PNEUMATIC ACTUATOR........................................................................................1411. ELECTRIC ACTUATOR...........................................................................................18

1. WHAT IS CONTROL VALVE ?

A Control Valve is a power -operated device used to modify the fluid flow rate in a process system.

There are two basic types of control valves:- TYPE A : Rotary motion valve having ball, butterfly or plug type closures.- TYPE B : Linear motion valve having globe, diaphragm or pinch type closures.

Control valve is controls and distributes pressure , flow, level, temperature and etc.

2. CONTROL VALVE CLASSIFICATION

Reference: Control Valve Classification.

3. LINEAR MOTION (CONTROL VALVE)

TYPES OF CLOSURE :

Globe : - Single Seated- Double Seated- Three way

Diaphragm Pinch

LINEAR VALVE FEATURES :

Tortuous flow path. Low recovery. Can throttle small flow rates. Offers variety of special tri designs. Suited to high-pressure application. Usually flanged or threaded. Separable bonnet.

4. GLOBE VALVE - (LINEAR MOTION)

Single Seated Globe Valve

Features :

Large amount of force required to drive the stem. Tight shut off. Used in small diameter applications.

Application :

Used for controlling large range of process parameters hance used in oil and gas production, power generation.

Double Seated Globe Valve

Features :

Steam can be driven with small amount of force. Can not achieve perfect closure resulting in leakage. Used in larger diameter application. Body parts wear out due to erosion and cavitations which result in

annoying noises.

Application :

Used for high flow and high pressure services.

Three Way Valve

Features :

High flow capacity. Valve used for mixing and diverting liquids. High rangeability. Leakage capability consistent with normal single seated globe valve.

Application :

Used in textile industries.

5. DIAPHRAGM VALVE - (LINEAR MOTION)

Features :

Consists of a saddle or seat upon which the diaphragm closes the valve. Can handle corrosive fluids.

Application :

Used as shut off valves in food and beverage, pharmaceutical and biotech industries.

6. PINCH VALVE - (LINEAR MOTION)

Features :

Tight shut off. The flexible sleeve allows the valve to close drop tight around solids,

solids that would typically be trapped by the seat or stuck in crevices in globe, diaphragm, butterfly, gate, or ball valves.

Application :

Best used in controlling corrosive fluids, steam and high pressure.

7. ROTARY MOTION

TYPES OF CLOSURE :

Ball Butterfly Plug

ADVANTAGES AND DISADVANTAGES OF ROTARY MOTION :

ADVANTAGES DISADVANTAGES Low weight. Generally not suitable below 1 to 2

inches. Simple design. Operating shaft must be designed to

support a fairly heavy side-thrust. High relative . Leakage problem. More reliable. Low initial cost. Friction-free packing.

8. BALL VALVE (ROTARY MOTION)

Features :

Tight shut off. Minimum obstruction for the flowing media. High flow capacity. Can withstand high pressure and temperatures.

Application :

Used for hazardous and corrosive fluids.

8. BUTTERFLY VALVE (ROTARY MOTION)

Features :

High flow capacity. Unlike ball valve the disc is present in the flow of the liquid and hence a

pressure drop is always induced in the flow. Tight shut off.

Application :

Used in steel, suger and textile industries.

9. ACTUATORS

An actuator is a component of machines that is responsible for moving or controlling a mechanism or system. An actuator requires a control signal and source of energy.

The control signal is relatively low energy and may be electric voltage or current, pneumatic or hydraulic pressure, or even human power.

THE MAJOR TYPES OF ACTUATOR ARE :

1. Pneumatic type2. Electric type

10. PNEUMATIC ACTUATOR

BASICALLY HAVE TWO TYPES :

1. Piston actuator.2. Diaphragm actuator.

PISTON ACTUATOR

They can withstand higher input pressure. Can offer small cylinder volumes. They are generally used where the stroke of a diaphragm actuator would

be too short or the thrust is too small.

DIAPHRAGM ACTUATOR

Compressed air applied to a flexible membrane called the diaphragm. This actuator is a single acting because air is supplied from single side of

the diaphragm.

11. ELECTRIC ACTUATOR

Electric actuators use an electric motor with voltage requirements in the following range: 230 Vac, 100 Vac,24 Vac and 24 Vdc.

There are two types of electric actuator :

1. VMD (valve motor drive).2. Modulating.

VMD (Valve Motor Drive)

Electric actuator has three stages :I. Driving the valve open.

II. Driving the valve closed.III. No movement.

MODULATING

In order to position the control valve in response to the system requirements a modulating actuator can be used.

It has positioning circuit . This actuator also has position sensor.