Pneumatic controllers
- 1. Prepared by: Bestin V Kallely Karunya University M.Tech Mechanical Engg. PR11ME1008
- 2. • Pneumatic controls are powered by compressed air. • Pneumatic Process control are safer than Electronic and controller's, when used in Explosive atmosphere like Chemical or Petrochemical plats.
- 3. Closed Lop Control 1. Controller 2. Actuator 3. Measuring Device (SP-Set Point, PV= Process variable)
- 4. • 1. Flapper Nozzle • 2. Volume Booster • 3. Force Balance Principle
- 6. • The heart of all pneumatic process control devices is a device to convert a small displacement into a pressure change. • This displacement is based on the Flapper Nozzle. Simple Differential Pressure Transducer
- 7. • 2. Volume Booster
- 8. • When Pressure given as input then linearly related pressure as output is obtained with an ability to supply a large volume of air.
- 9. 1. Air Relay
- 10. • An increase in input signal cause air to pas from the supply to the load, while a decreasing input signal cause air to vent from the load.
- 12. • The force from the feedback bellows match the force from the input signal bellows and output pressure directly proportional to (P1-P2)
- 13. From the figure 1, closed loop control OP = K x ERROR = K x ( SP – PV ) ( where K is Gain) Proportional only Controller ( Simplest Pneumatic Controller)
- 15. • Any output signal an error exist this error is called Offset Error.
- 17. Where D is Derivative Time ( User Adjustable)