7 Main Difference Between Hydraulics and Pneumatics | The Engineers Post

Difference Between Hydraulic and Pneumatic

Hydraulics and Pneumatics

The basic concept of hydraulics and pneumatics.

Fluid mechanics is that branch of science which deals with the behaviour 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.

Let’s start with hydraulics.

1. Hydraulics

Fluid can define as a substance which 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 surrounding removed.

In physics, a fluid is a substance that continually deforms under an 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 using for the conversion of hydraulic energy into mechanical energy to do some useful work.

In the heating, ventilation, and air-conditioning industry (HVAC), the liquid such as water is using for transmission of heat from one area to another.

Fluid is a primary element of a hydraulic system, which obeys Pascal’s law to give the fluid power.

Example 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.

Classification of Fluid:

Some of the important types of fluid as follow:

  1. Ideal fluids
  2. Real fluids
  3. Newtonian fluids
  4. Non-Newtonian fluids
  5. Ideal plastic fluids.

Properties of Fluids:

Some of the main properties of the fluid as follow:

  1. Density or mass density or specific mass
  2. Specific weight
  3. Specific volume
  4. Surface tension
  5. Viscosity
  6. Surface tension
  7. Capillarity
  8. Compressibility
  9. Specific gravity

2. Pneumatics

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 in which use a 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 contains 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 as follow:

  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 compare to other systems.
  9. Fire-proof characteristic of the medium.
  10. Possibilities of easy but reliable in remote controlling.

Applications of Pneumatic systems:

some of the important applications of the pneumatic systems as follow:

  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. Using for breaking system 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.

Examples of pneumatic systems and components:

  • Air compressors and air brakes
  • Air engines for pneumatically powered vehicles
  • Compressed-air engine 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

3. Difference between Hydraulics and Pneumatics

Difference between hydraulics and pneumatics

In hydraulics and pneumatics, hydraulics is liquid and pneumatics is gas.


The main difference between these two is, 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 have less maintenance cost.

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