Question

Flapper nozzle is used in following controller?

• A. Hydraulic
• B. Electric
• C. Pneumatic
• D. Electronic

Hint:

Flapper-nozzle systems are a hallmark of \textbf{pneumatic controllers} — they convert small mechanical displacements into pressure changes.

Answer 1

The Correct Option is C

The flapper-nozzle system is a fundamental component of pneumatic controllers, which are widely used in process control systems.
Here’s how it works:
- The system consists of a nozzle that emits compressed air and a flapper (a mechanical arm or plate) placed close to the nozzle.
- As the flapper moves closer to or farther from the nozzle, it changes the back pressure in the nozzle.
- This pressure variation is used to generate a control signal in a pneumatic loop.
Key Points:
- Pneumatic controllers work on compressed air or gas, not hydraulic fluids or electricity.
- They are commonly used in hazardous or explosive environments where electrical devices may pose a risk.
- Hydraulic controllers use pressurized fluids, not air.
- Electric and electronic controllers rely on voltage/current signals, not air pressure.
Therefore, the flapper-nozzle mechanism is specific to pneumatic controllers.