Basic parts of control valves

Introduction 

in this session we are gonna discuss about the parts of control valves

DIAPHRAGM CASE

Use to enclose the diaphragm to form a pressure chamber, one above the diaphragm and one at the bottom of the diaphragm.  The sealing surfaces of the slope away from the diaphragm at the outer edge to insure a pressure tight seal inside the bolt circle at the inner edge

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DIAPHRAGM

A flexible piece of material that flexes in response to the pneumatic signal from the controller.  The moulded diaphragm in combination with deep diaphragm case provides a remarkably constant effective area throughout the valve travel

DIAPHRAGM  PLATE

A metal plate that fits the moulded diaphragm and transmit the diaphragm force to the stem.

ACTUATOR SPRING

Opposes the air pressure force on the diaphragm to control the movement of the actuator. It also pushes the actuator to back up to original position when air pressure fails.

ACTUATOR STEM

A metal rod that connects the diaphragm plate to the valve stem.

SPRING SEAT

A piece of metal that holds the actuator spring in position.

SPRING ADJUSTER

A hexagon heads adjuster and is easily accessible to adjust the compression of the actuator spring.  Adjusting the tension of the actuator spring will determine the initial movement of the actuator when pneumatic signal is applied.

YOKE

A structure by which the diaphragm case or cylinder assembly is supported rigidly on the bonnet assembly.

STEAM CONNECTOR

Is a split nut threaded to engage the actuator on one end and the valve stem on the other end.  The two halves are bolted together to provide a connection that prevents loosening due to torque reactions of valve stem,

TRAVEL INDICATOR

The travel indicator is a stainless steel with its edges cupped downward to add rigidity and also provide a definite position reference.

TRAVEL INDICATOR SCALE

A graduated scale attached to the yoke for indication of valve travel.

VALVE STEM

A rod connected to the actuator stem and extended through the bonnet assembly to permit positioning the valve plug

YOKE LOCK NUT

Is a rugged lock nut use to fastened the actuator and the valve body.  The arrangement of fastening the two parts provide the correct alignment of actuator and body plus adequate strength.

PACKING FLANGE

Use to hold the packing material inside the packing box.

PACKING FOLLOWER

Use to guide and compress the packing material through the bonnet hole.

PACKING      

Use to provide seal and prevent leaks through the bonnet hole.To know more about stem packing

PACKING BOX

Enclosed the sealing components where the valve stem enters the bonnet or valve body.

BONNET 

The bonnet enclosed the valve plug in the valve body.

VALVE PLUG 

A movable part which provides a variable opening in a port.

SEAT RING

Comes in contact with the valve plug to seal the valve tight during close position.

VALVE BODY

  A housing for internal parts having inlet and outlet flow connections.  The term valve body or even just body, frequently is used in referring to the valve body together with its bonnet assembly and included trim parts.  More properly this group of components should be called the valve body assembly.

 

News Reporter

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