All of about control valve

 CONTROL VALVE

> Control valve is the final control element which is used to regulate material flow in the process.  

                          OR

> control valve it used to control the flow of pipelines.

Company: Fisher

                     Masoneilan

                      Ratark

                      Demla

                      Samson

                      Valtek

                      Mil control

Types of control valve depending on body

1.Single seated valve

2.Double seated valve

3.Angle valve

4.globe valve

5.Butterfly valve

6.Ball valve

7.three way valve

8.Needle valve

9.Pinch valve

Depending on action

1.Air to open ( fail to close) 

2.Air to close ( fail to open) 

Types of Actuator

1.Pneumatic ( single acting & double acting) 

2.Pneumatic piston Actuator

3.Hydraulic Actuator

4.Electric Actuator

Parts of control valve

1.positioner

2.Actuator

3.diaphragm ( rubber) 

4.spring

5.stem

6.yoke

7.scale

8.Travel indicator ( indicating edge) 

9.feedback link 

10.valve body

11.plug

12.plug seat

13.gland packing

14.gland pusher

15.gland nut

16.Bonnet

17.stem connector

18.stem nut

19.cage

Accessory of control valve

1.Positioner

2.Air filter regulator

3.Solenoid valve

4.Volume Booster

5.Hand wheel

6. Limit switch

7.Air lock Relay 

8.I to P converter

Types of valve positioner

1.Pneumatic positioner

2.Electro Pneumatic positioner ( E/P) 

3.Electro pneumatic smart positioner

Control valve with positioner

Use of valve positioner

1.zero and span can be adjust using positioner

2.quicj action of control valve stem traveling will be fast

3.valve Hydterisis will be zero ( error zero) 

4.valve can be used for viscous liquid

5.if line pressure change there will be no effect on control valve. 

6.valve action can be change from Fc to found Fo to Fc

Calibration of control valve

> Connect ma source at (+) and (-) terminal of positioner

> Apply Air supply to positioner

>Apply 4.00 ma and check 0℅ at control valve. If it disturbed than adjust is using positioner. 

> Apply 8.00 ma and check 25℅ at control valve. 

> Apply 12.00 ma and check  50℅ at control valve. 

> Apply 16.00 ma and check 75℅ at control valve. 

>Apply 20.00 ma and check 100℅ at control valve. If it disturbed than adjust it using positioner. 

In field /online calibration

> Take a work permit. 

> Take a loop manual from dcs

> Take control valve by pass from line. 

>Remove cable which is coming from dcs. 

>connect ma source at positioner. 

>Apply 4.00 ma and check 0℅  at control valve. If it is dusturbed adjusted using positioner. 

>Apply 8.00 ma and check 25℅ at control valve

> Apply 12.00 ma and check 50℅ at control valve. 

> Apply 16.00 ma and check 75℅ at control valve. 

> Apply 20.00 ma and check 100 ℅ at control valve. If it disturbed than adjust by using positioner. 

> Take loop  in auto from dcs