Fluid Power Symbols

Chapter: 7

Fluid Power Symbols

"True knowledge exists in knowing that you know nothing. And in knowing that you know nothing, that makes you the smart- est of all."

- Socrates

"Any one who has never made a mistake has never tried anything new.”

- Albert Einstein

"Men have become the tools of their tools."

- John Tudor

Learning Objectives

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

• Appreciate the need for fluid power symbols. 

• Have a knowledge of fluid power symbols. 

• Apply the proper graphic symbols while designing the fluid power system.

1. INTRODUCTION

• Due to the rapid development of fluid-power applications, standard fluid power symbols and specifications are developed to facilitate communication and to provide a universal means of representing fluid-power systems.

• Graphic fluid power symbols, similar to symbols used in electrical circuit diagrams, are now widely used both for preparing hydraulic and pneumatic circuit diagrams and as an aid in circuit design and analysis.

• The fluid power symbols illustrate flow paths, connections, and component functions. But they do not indicate operating parameters and/or construction details.

Therefore it is mandatory for any fluid power designer or engineer to have a thorough knowledge of fluid power symbols so that he/she can read, understand, design, analyse, and apply the fluid power systems. In this chapter, we shall discuss about the various graphic symbols used in hydraulic and pneumatic systems.

1. Fluid Power Symbols

• As discussed above, symbols are used to represent individual components in fluid power circuit diagrams, which identify components and their functions uniquely.

• The symbols, however, do not provide any of their construction details and operating parameters.

• The symbols explained in this chapter are based on the International Organisation for Standardisation [Standard DIN ISO 1219]. Also these symbols conform to the American National Standards Institute (ANSI).

• The various fluid power symbols used in fluid power circuits are explained below under the eleven basic symbol classifications. †  They are:

1. Pumps and motors;

2. Cylinders;,

3. Directional control valves;

4. Pressure valves;

5. Flow control valves;

6. Non-return valves;

7. Operation/actuation methods; 

8. Energy transmission; 

9. Measuring devices;

10. Couplings, and

11. Combination of devices.

• This chapter presents only the graphic symbols for the various fluid power components. However, other details such as function, design, construction, and working of these components will be presented in the preceding chapters.

Readers need not bother too much about the fluid power symbols right now. Because the symbols can be better understood while studying along with their respective topics in subsequent chapters.

Now, we shall explain the above symbols, one by one, in the following sections.