Pooyan Hydraulics - Basic Symbols - 1.1

Nov 1, 2026

Pooyan Hydraulics provides a structured reference for ISO fluid power graphic symbols, describing basic and functional symbol sets and how to interpret their line styles, shapes, and annotations. It defines dash length, line thickness, and spacing relationships, and explains the meaning of circle, square/rectangle, and diamond forms. The document also covers functional elements such as triangles for flow direction and fluid type, arrows indicating direction, rotation, and valve flow paths, and sloping arrows that represent regulation or progressive variability, followed by equipment symbol usage for pumps, compressors, motors, and pump/motor units.

LanguageEnglish

CategoryTechnology

FormatPDF

Pages20

Reading Time50 min

AccessFree to download

Basic Symbols

Line styles and dash parameters

Circle and semicircle symbols

Square and rectangle symbols

Diamond conditioning apparatus symbols

Functional Symbols

Triangles for hydraulic and pneumatic flow

Arrows for direction and valve paths

Sloping arrows for regulation variability

Pumps and Compressors

Fixed capacity hydraulic pumps

Variable displacement hydraulic pumps

Fixed capacity compressors

Motors

Fixed capacity hydraulic motors

Variable displacement hydraulic motors

Displacement pneumatic motors

Pump/Motor Units

Pooyan Hydraulics DESCRIPTION SYMBOL APPLICATION | 1.1 | BASIC SYMBOLS | | | | --- | --- | --- | --- | | 1.1.1
1.1.1.1
1.1.1.2
1.1.1.3
1.1.1.4
1.1.1.5 | Line
—continuous
—long dashes
—short dashes
—double
—long chain thin (optional use) | 2)
| } flow lines
mechanical connections (shafts, levers, pistonrods)
Enclosure for several components assembled in one unit | | 1.1.2 | Circle, semi-circle | | | | 1.1.2.1 | | | As a rule, energy conversion units (pump, compressor, motor) | | 1.1.2.2 | | | Measuring instruments | | 1.1.2.3 | | | Non-return link, roller, etc | | 1.1.2.4 | | | Mechanical link, roller, etc. | | 1.1.2.5 | | | Semi-rotary actuator | 2) L= Length of dash, E = Thickness of line, D = Space between lines I S O F L U I D P O W E R G R A P H I C S Y M B O L S DESCRIPTION SYMBOL APPLICATION | 1.1.3 | Square, rectangle | | | As a rule, control valves (valve) except for nonreturn valves | | --- | --- | --- | --- | --- | | | |
| | | | 1.1.4 | Diamond | | | Conditioning apparatus (filter, separator, lubricator, heat exchanger) | | 1.1.5
1.1.5.1
1.1.5.2
1.1.5.3
1.1.5.3.1
1.1.5.3.2 | Miscellaneous symbols | 3)

d ≈ 5E

| | Flow line connection Spring
Restriction:
— affected by viscosity
— unaffected by viscosity | | 1.2 | FUNCTIONAL SYMBOLS | | | | | 1.2.1
1.2.1.1
1.2.1.2 | Triangle:
—solid
—in outline only | | | The direction offlow and the nature of the fluid Hydraulic flow
Pneumatic flowor exhaust to atmosphere | | 1.2.2
1.2.2.1
1.2.2.2
1.2.2.3 | Arrow | | | Indication of:
— direction
— direction of rotation
— path and direction offlow through valves. For regulating apparatus as in 3.4 both representations, with or without a tail to the end of the arrow, are used without distinction As a general rule the line perpendicular to the head of the arrow indicates that when the arrow moves, the interior path always remains connected to the corresponding exterior path | | 1.2.3 | Sloping arrow | | | Indication of the possibility of a regulation or a progressive variability | I S O F L U I D P O W E R G R A P H I C S Y M B O L S DESCRIPTION SYMBOL USE OF THE EQUIPMENT OR EXPLANATION OF THE SYMBOL | 2.1 | PUMPS AND COMPRESSORS | | To convert mechanical energy into hydraulic or pneumatic energy. | | | --- | --- | --- | --- | --- | | 2.1.1
2.1.1.1 | Fixed capacity hydraulic pump:
—with one direction of flow | | | OUTLET | | | | | |
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| | | | | | | | 2.1.2
2.1.2.1 | Variable displacement hydraulic pump:
—with one direction of flow | | The symbol is a combination of [2.1.1.1](2.1.1.1)[ ](2.1.1.1)and 1.2.3 (sloping arrow) |

U
| | 2.1.2.2 | —with two directions of flow | | The symbol is a combination of [2.1.1.2](2.1.1.2)[ ](2.1.1.2)and 1.2.3 (sloping arrow) |

FAQs

What do dash length (L), line thickness (E), and spacing (D) represent in the symbols?

They define how line-and-dash proportions are used in the graphic symbols, with d approximately equal to 5E.

How are triangle and arrow symbols used to indicate fluid flow?

Triangles indicate the direction of flow and the nature of the fluid (hydraulic flow or pneumatic flow/exhaust). Arrows indicate direction, direction of rotation, and the path/direction through valves.

What is the meaning of sloping arrows in ISO fluid power symbols?

Sloping arrows indicate the possibility of regulation or progressive variability.

Nov 1, 2026

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