Unit SixUnit Six

Control of Pneumatic EnergyControl of Pneumatic EnergyPneumatic energy must be controlled in order to Pneumatic energy must be controlled in order to accomplish useful work and be safe.accomplish useful work and be safe.

There are three quantities that must be controlled.There are three quantities that must be controlled.

PressurePressure

DirectionDirection

FlowFlow

ValvesValves

As stated earlier, there are three quantities that must be As stated earlier, there are three quantities that must be controlled and they are all controlled by valves.controlled and they are all controlled by valves.

All valves consist of basically the same parts. They each All valves consist of basically the same parts. They each have a body, internal moving part, and ports to connect have a body, internal moving part, and ports to connect the valve to the system.the valve to the system.

Control of PressureControl of Pressure

In most cases, the pressure generated at the compressor In most cases, the pressure generated at the compressor and what is required by the system are different so and what is required by the system are different so pressure has to be controlled at two locations.pressure has to be controlled at two locations.

Pressure Control SwitchPressure Control Switch

Maximum pressure control in pneumatics is usually accomplished Maximum pressure control in pneumatics is usually accomplished by the use of an electrical switch although some large systems use by the use of an electrical switch although some large systems use mechanical devices. With the switch, contacts are opened or closed mechanical devices. With the switch, contacts are opened or closed to stop an electric motor.to stop an electric motor.

Pressure Control ValvePressure Control Valve

Safety ReliefSafety Relief

If for some reason the electrical switch or mechanical If for some reason the electrical switch or mechanical device should fail to stop the compressor at the right device should fail to stop the compressor at the right time, a fail safe device opens to permit the escape of air.time, a fail safe device opens to permit the escape of air.

Pressure Control ValvePressure Control Valve

Pressure RegulatorPressure Regulator

The pressure regulator valve controls pressure in branch legs of The pressure regulator valve controls pressure in branch legs of a pneumatic system such as drop legs for individual machines.a pneumatic system such as drop legs for individual machines.

Directional Control ValveDirectional Control Valve

Fluid must be directed to different points in order to Fluid must be directed to different points in order to control an actuator. The DCV controls where the fluid control an actuator. The DCV controls where the fluid goes.goes.

Flow Control ValveFlow Control Valve

The basic operation of the flow control valve is to The basic operation of the flow control valve is to “pinch” off flow to adjust the speed of an actuator.“pinch” off flow to adjust the speed of an actuator.

Simple Pneumatic SystemSimple Pneumatic System

This type of drawing is referred to as a “pictorial”diagram.This type of drawing is referred to as a “pictorial”diagram.

Simple Hydraulic SystemSimple Hydraulic System

This illustration is called a “schematic” diagram and This illustration is called a “schematic” diagram and is commonly used in industry.is commonly used in industry.

Hydraulic SymbolsHydraulic Symbols

These are some of the most often used symbols you will see in These are some of the most often used symbols you will see in industry and this course. Make a point to become familiar with industry and this course. Make a point to become familiar with them.them.