Fluid power

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Fluid power is the technology that deals with the generation, control, and transmission of pressurized fluids.

As the term fluid refers either to gases or to liquids, fluid power is also subdivided into the categories of hydraulics and pneumatics. The differences being that with hydraulics the medium used is a liquid (ie mineral oil or water) and for pneumatics it is a gas (ie air or another inert gas).

Contents 1 Practical use 1.1 Transport fluid 1.2 Transport energy 2 Application 3 References 4 See also 5 External links

[edit] Practical use

In practice fluid power is used to achieve one of two generic tasks:

[edit] Transport fluid

Delivering the fluid from one location to another to achieve a useful purpose.
An example of this in the case of hydraulics in a lube oil or grease system to provide oil or grease to lubricate bearings on heavy equipment.

[edit] Transport energy

In this case the fluid flow is used to actuate a device specifically designed to operate from the flow provided. In general, these actuators fall into the following categories:

• Cylinder (hydraulic or pneumatic): Provides force in a linear fashion
• Motor (hydraulic or pneumatic): Provides continuous rotational motion
• Rotary actuator: Provides rotational motion of less than 360 degrees.

[edit] Application

Hydraulics and pneumatics are similar in many ways, but there are clear reasons for using one over the other.

• Cost: Pneumatics are considerably cheaper to build and operate. For one, air is used as the compressed medium, so no reservoir is needed to store fluid, nor is there any need to provide means to drain or recover fluid. With increasing working pressures, pneumatics require larger parts than hydraulics.
• Precision: Unlike liquids, gases change volume significantly when pressurized making it difficult to achieve precision.
• Safety: Gases tend to want to expand at high velocities when compressed, thus pneumatics are typically limited in utilities with a working pressure up to around 100 psi (7 bar).

[edit] References

• Esposito, Anthony, Fluid Power with Applications, ISBN 0-13-010225-3

[edit] See also

• London Hydraulic Power Company
• Pneumatics
• Pneumatic circuit
• Pneumatic actuator

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[edit] External links

• Information about Fluid Power is also available on the National Fluid Power Association web-site nfpa.com
• Using Equivalent Lengths of Valves and Fittings