Pneumatic Valves and Actuators

Chapter: 12

Pneumatic Valves and Actuators

"The ultimate measure of a man is not where he stands in moments of comfort and convenience, but where he stands at times of challenge and controversy"

- Martin Luthur King, Jr.

"Yesterday I dared to struggle. Today I dare to win"

- Bernodette Devlin

"Patience and persever- ence have a magical effect before which difficulties disappear and obstacles vanish."

– John Quincy Adams

Learning Objectives

While reading and after studying this chapter, you will be able to:

• Identify, understand, and appreciate the various air control valves required for proper functioning of the pneumatic systems.

• Understand and explain the construction, operation, and application of various directional control valves (such as check valves, two-way, three-way, four- way DC valves, shuttle valves, and quick exhaust valves).

• Understand and explain the construction, operation, and application of air pressure regulator and flow control valve.

• Identify and describe the construction, operation, and application of various types of pneumatic cylinders.

• Identify and describe the costruction, operation, and application of various types of air motors.

INTRODUCTION

Like in hydraulic systems, pneumatic systems also require control valves to direct and regulate the flow of air from compressor to the various load devices. As we know, in order to control the movement of pneumatic actuators, the compressed air has to be regulated, controlled, and reversed with a predetermined sequence. Also one has to control the pressure and flow rate of the working medium (compressed air) to produce the desired level of force and speed of actuators. These functions are achieved with the use of pneumatic valves.

We need to convert the pressure energy of air (called pneumatic energy) into mechanical energy to perform useful works. This function is accomplished by the devices known as pneumatic actuators. Like in hydraulic systems, pneumatic actuators also use both pneumatic cylinders and air motors. The pneumatic cylinders generate motion in a straight line to perform the work. The air motors generate rotary output motion to perform the work.

In this chapter, we shall discuss the principle, construction, and application of various control valves and actuators employed in a pneumatic system.