Page 316 - CITS - Electronic Mechanic - TT - 2024

ELECTRONICS MECHANIC - CITS

LESSON 188 - 198 : Electronic pnuematic

Objectives

At the end of this exercise you shall be able to
• state various types of pneumatic actuator & their priciple.

Pneumatic Actuator is a device that converts the energy of compressed air or gas into mechanical motion. Here,
depending on the motion obtained by the actuator, the actuator can be rotary or linear type. “Pneumatic actuators
are known to be a highly reliable, efficient and safe source of motion control.”
A pneumatic actuator diagram is given below showing different configurations-

Pneumatic actuator Valve
A pneumatic actuator converts pneumatic energy into mechanical energy which controls a final control element
such as a control valve according to the received control signal. The pneumatic actuator used to operate the con-
trol valve is called pneumatic actuator valve. Normally in industries, pneumatic systems use air pressure of (80 to
100) PSI for their operation. Actuator valves primarily consist of a diaphragm or a piston surrounded by a metallic
enclosure and a stem attached to the diaphragm or piston which can be connected to the valve stem through a
coupling. They can have either a single pneumatic signal port with a spring return mechanism which is referred to
as a single acting actuator or it can have a double pneumatic signal port which is referred to as a double acting
actuator. Apart from this, according to the valve type, linear or rotary actuator is connected. The diagram of a simple
pneumatic actuator valve is shown below-

Push button switches
• Momentary push buttons return to their unactuated position when they are released.
• Maintained (or mechanically latched) push buttons has a latching mechanism to hold it in the selected position.
• The contact of the push buttons, distinguished according to their functions,

• Normally open (NO) type
• Normally closed (NC) type
• Change over (CO) type.
Normally open type
• In the NO type, the contacts are open in the normal position, inhibiting the energy flow through them.
• But in the actuated position, the contacts are close

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