Pneumatic vs. Hydraulic – What is the difference?

What is the Difference between pneumatics and hydraulics?

Hydraulics and pneumatics are both examples of fluid power. The difference lies in the fluid used and how those fluids are used. Only fluid power systems are capable of providing constant force or torque despite speed changes.

Although these are almost the same in terms of mechanism, the main difference is in their methods of transporting power to the equipment to exert the needed pressure in performing certain tasks.

Hydraulics employ fluids, such as oils, while pneumatics utilizes compressed gases. Both systems have their own distinct benefits and ideal applications, such as heavy lifting and operating costs.

The difference between pneumatics and hydraulics actually lies in the medium that is utilized to transmit power. Pneumatics use easily compressible gas like air or pure gas.

Meanwhile, hydraulics utilizes relatively-incompressible liquid media like mineral oil, ethylene glycol, water, synthetic types, or high-temperature fire-resistant fluids to make power transmission possible.

Because of this primary difference, some other aspects about these two power circuits also follow suit. Industrial applications of pneumatics utilize pressures ranging from 80–100 pounds per square inch, while hydraulics use 1,000–5,000 psi or more than 10,000 psi for specialized applications.

Moreover, a tank would be needed in order to store the oil by which the hydraulic system can draw from in cases of a deficit. In a pneumatic system, however, air can simply be drawn from the atmosphere then purified via a filter.

What does a hydraulic system do?

Instead of air, machines that use hydraulics rely on mostly incompressible liquid material under pressure to lift, hold and move goods. Examples include hydraulic or mineral oil, or water, just to name a few.

Advantages:

  • Moves heavier loads with greater force than mechanical, electrical or pneumatic fluid power systems
  • Ease and accuracy of controlling the system by levers and push buttons
  • Generates large amounts of power
  • Uses fewer moving parts than some mechanical and electrical systems, which makes it more durable and less prone to break down

What does a pneumatic system do?

Pneumatic machinery and equipment use pressurized gasses, such as air, for moving and cooling applications. Pneumatic fluid power systems compress air, so movement is not instantaneous, as it is with hydraulics.

Advantages:

  • More cost effective than hydraulics – air is free
  • Pneumatic safety – system can be used in inflammable environments and does not
  • More power in a smaller and lighter unit compared to most other technology systems
  • Cleaner technology
  • Fluid used absorbs excessive force, which means fewer threats of damage to equipment
Pneumatic Vs. Hydraulic

Pros And Cons of Hydraulics and Pneumatics

hydraulic wrenching terms of sustainability, air-pressure powered tools are typically used when performing maintenance of valves and flanges because the pressure they use is more controllable.

Pneumatics display rapid movement of gears and have the advantage of availability in very small sizes. This is mainly due to air compressor flow rates. Air is very agile and can flow through hoses very quickly and easily with little resistance, while hydraulic oil is a viscous substance and requires more energy to move.

Pneumatics offers a very clean system, suitable for food manufacturing and other processes that require no risk of contamination. Due to the risk of hydraulic oil leaks from faulty valves, seals, or burst hoses, hydraulics are generally not used in these environments.

Pneumatic tools and valves can dump their compressed air straight to the atmosphere when they need to change direction or alter their state quickly, compared with hydraulic pumps where the oil must be routed back to the reservoir.

However, pneumatics does not have the potential force that hydraulics has to offer. Typical pneumatic systems operate at around 80 to 100 pounds per square inch of pressure, with pressures greater than this restricted by the materials used within the system.

Hydraulic jacks can smoothly lift and move large loads because the hydraulic oil is not compressible. In general, a much larger pneumatic cylinder is needed to obtain the same force that a hydraulic ram can produce.

Best Uses for Hydraulics and Pneumatics

Pneumatics

Pneumatics are typically used in factory setups, construction, mills, building, and technology by using a central source of compressed air for power. Medical applications of pneumatics are likewise common including the high-powered drill of a dentist.

Practically everything could run on pneumatics including any form of transportation. That little tube in a bank’s drive-teller operates through pneumatics via a high-pressure source of compressed air.

Hydraulics

Hydraulics have varied uses in everyday life and most of them are applicable to machines. For instance, hydraulics is applied in a car’s braking system. They only require a small force as the driver steps on the car brakes but a greater force is already produced to stop or slow down a car as it equally acts on all of the 4 brake pads.

Hydraulic applications are also evident in lifting equipment such as wheelchair lifts, excavating arms on machinery like diggers, hydraulic presses for forging metal parts, and wing flaps on aircraft. The obvious uses of hydraulics are with heavy equipment.

Cost of Hydraulics and Pneumatics

When it comes to cost-effectiveness, pneumatic systems are cheaper and easier to maintain than hydraulics. Materials used when manufacturing air-powered tools tend to last longer than of oil-powered equipment.

Looking at operation cost, pneumatic is cheaper as well, and in some cases, even hydraulic power needs the assistance of compressed air to produce the needed power for hydraulic equipment to work.