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7 Difference Between Hydraulics and Pneumatic [PDF]

In this article, you’ll learn what is the Difference Between Hydraulics and Pneumatic system. And also you can download the PDF file of this article at the end of it.

Difference Between Hydraulics and Pneumatic:

First, let’s start with hydraulics and pneumatic definitions.

Fluid mechanics is that branch of science that deals with the behavior of the fluids at rest as well as in motion. Pneumatics is a branch of engineering that makes use of gas or pressurized air.

Both hydraulics and pneumatics are the application of fluid power. In its fluid power applications, hydraulics is used for the generation, control, and transmission of power by the use of pressurized liquids.

What is Hydraulics?

Fluid can define as a substance that is capable of flowing and does not maintain its shape for a long time. Fluids have the ability to take the shape of the container depending on the surroundings and flow in a large area when the surroundings is removed.

In physics, a fluid is a substance that continually deforms under applied shear stress. Fluids are a subset of the phases of matter and include liquids, gases, plasmas, and to some extent, plastic solids. Fluid such as water is used for the conversion of hydraulic energy into mechanical energy to do some useful work.

In the heating, ventilation, and air-conditioning industry (HVAC), liquid such as water is used for the transmission of heat from one area to another. The fluid is a primary element of a hydraulic system, which obeys Pascal’s law to give fluid power.

Examples of Hydraulics systems: Jaws of Life, dump truck lifts, water guns, forklifts, cranes, etc.

Advantages of Hydraulics

  • In general, it is simple, safe and economically easier to maintain. Hydraulic systems use fewer moving parts in comparison with mechanical and electrical systems.
  • Compared to pneumatics it is highly responsive and supplies more power than pneumatics.
  • The liquid does not absorb any of the supplied energy.
  • By the use of simple levers and push buttons, it can be easily controlled.  The operator of a hydraulic system can easily start, stop, speed up and slow down.

Application of Hydraulic Systems

  1. They are utilized in gasoline pumps, which suck fuel from the storage tank into the car using hydraulics.
  2. A car’s brakes are controlled by a hydraulic braking circuit.
  3. The ability to raise and lower an extremely heavy car for maintenance is made possible by a hydraulic system.
  4. Hydraulics is used in dishwashers to raise water pressure for better cleaning.
  5. Hydraulics is used by machinery like cranes, forklifts, jacks, pumps, and fall arrest safety belts to raise and lower objects.
  6. The control panels of airplanes are operated by hydraulic mechanisms.
  7. Certain elevator models employ a hydraulic mechanism to drive the movement of the elevator cars and bring them to a stop when necessary.

Read also:

What is Pneumatic?

Pneumatic is the branch of physics or technology concerned with the mechanical properties of gases. Pneumatic can also be defined as a branch of fluid power that uses gas as a fluid. There are two types of gases are used in pneumatic systems such as compressed air and Nitrogen.

Compressed air is a mixture of all gases contained in the atmosphere. The unlimited supply of air and the ease of compression make compressed air the most widely used fluid for pneumatic systems.

Advantages of the Pneumatic System

Some of the main advantages of pneumatic systems are as follows:

  1. Availability of air.
  2. The compressibility of air.
  3. Compressed air is easy to transport in pressure vessels, containers, and pipes.
  4. Simple in construction and easy to handle.
  5. Controlling the ability to pressure, speed and force is high.
  6. Maintenance is low.
  7. Explosion-proof characteristic of the medium.
  8. Cost is low as compared to other systems.
  9. Fire-proof characteristic of the medium.
  10. Possibilities of easy but reliable remote controlling.

Applications of Pneumatic Systems

Some of the important applications of pneumatic systems are as follows:

  1. Using for packing.
  2. Using for filling.
  3. In drilling, hoisting, punching, clamping, assembling, riveting.
  4. Opening and closing the doors.
  5. Used in industrial robots.
  6. For power hammers and nut runners.
  7. Used in riveting hammers.
  8. Used for breaking systems in automobiles, railway coaches, wagons, and printing presses.
  9. Used in metal forming processes.
  10. Used in material handling types of equipment and logic controlling operations.

Difference between Hydraulics and Pneumatics

Following are the 7 main differences between hydraulics and pneumatic:

In hydraulics and pneumatics, hydraulics is liquid and pneumatics is gas. And, the main difference between these two is that hydraulic systems use liquids like water and oil to transmit power. Where pneumatic systems use air to transmit power.

In hydraulics, liquids are relatively incompressible. Liquids have high specific mass and have a free surface. A tank is used to store the oil. In pneumatics, gases are readily compressible.

They have a very low specific mass and gases do not have a free surface. In a pneumatic system, air can simply be drawn from the environment and purified using a filter.

Hydraulic systems are used for high force and where stiffness in position is necessary. They move relatively slowly but can handle higher loads. The installation is complex and the maintenance cost is high.

Pneumatic systems are used for relatively lower forces, faster motion, and where stiffness isn’t required. They have a very controlled force, regardless of stroke or load resistance. Installation of this system is less complicated and has less maintenance cost.

Difference between hydraulics and pneumatic

Examples of Pneumatic Systems and Components

  • Air compressors and air brakes
  • Air engines for pneumatically powered vehicles
  • Compressed-air engines and compressed-air vehicles
  • Pneumatic anti-aircraft weapon
  • HVAC control systems
  • Pneumatic actuator, air gun, Cylinders, motor and tire
  • Pneumatic tools: Jackhammer, nailgun
  • Pressure regulator, sensor, switch
  • Vacuum pump

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Read more:

  1. How Centrifugal Pump Works
  2. What are Flow Control Valves? Diagram, Types, Working & Uses [PDF]
  3. What are the Different Properties of Fluids? [Explained with Calculations]
About Saif M

Saif M. is a Mechanical Engineer by profession. He completed his engineering studies in 2014 and is currently working in a large firm as Mechanical Engineer. He is also an author and editor at www.theengineerspost.com

4 thoughts on “7 Difference Between Hydraulics and Pneumatic [PDF]”

  1. Dear Sir,

    Welldone Sir, kindly provide me a comprehensive and well arranged lecture note on Hydraulic and Pneumatic System as applied to Civil Engineering.

    Warmest regards.

    Yours Sincerely,

    Engr. Ogunjemilua .I. Oluwatato

    • Sure! thanks for the comment, we will provide you the detailed notes through email 🙂


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