Difference between Pneumatic and Hydraulic Systems

Pneumatic Valve System

Pneumatic and hydraulic systems are both used to transmit mechanical energy. You’ll often see them used in power tools, heavy machinery and vehicles. In terms of components, these systems also have a few similarities. They typically have filters, actuators, solenoid valves and/or other forms of directional control valves.

But what makes them different from each other? What would be the reasons you would choose one over the other? In this blog, we’re going to discuss the main differences between pneumatic and hydraulic systems as well as their most common applications.

Pneumatics vs. Hydraulics

Pneumatics refers to the use of air (or other forms of compressible gas) to channel mechanical energy within a particular system. The air that’s used for pneumatic systems is typically taken directly from the atmosphere via a filtered inlet. After that, the air then runs through a compressor, along the pipeline, and through to a directional control valve. Here you can control where the compressed air goes. It can be released via an exhaust or taken to the actuator where the compressed air energy is converted into motion.

In contrast, hydraulics refers to the use of non-compressible liquids like oil and water to control kinetic energy. In a hydraulic system, you’ll typically need a lot more components than a pneumatic system. For one, a hydraulic system often requires a large reservoir for the non-compressible liquid. Due to the risk of the liquid becoming contaminated, it is important that this reservoir is protected and maintained properly. A motor and a pump are also required to carry the liquids through the pipes against the pull of gravity.

Towards the other end of the hydraulic circuit, the system becomes similar to the pneumatic circuit. The liquid will run through a directional control valve, where you can redirect its flow. Finally, it will reach the actuator where the pressurised liquid energy is turned into mechanical energy.

Differences in performance and application

Solenoid Valve

Pneumatic systems

  • Cleaner circuits

Since pneumatic systems use clean air, you won’t have to worry about contamination. Because of this, pneumatic systems are typically used in settings where hygiene and cleanliness are paramount. This includes the pharmaceutical industry, food processing plants and various medical facilities.

  • Repetitive movements

Taking air directly from an atmosphere is an economical method of harnessing energy. That said, compressible air simply can’t be used to support heavy loads or produce as much force as hydraulic systems.

As a result of this, pneumatic systems are more suitable for simple, repetitive mechanical movements like punching, clamping, pressing and stamping. You’ll often see these such mechanisms in the mining and manufacturing industries.

  • Environmentally friendly

After the compressed air has been used, it can simply be released back into the atmosphere via an exhaust port. Not only does this make the process more efficient, it’s also of great benefit to the environment. Indeed, you won’t have to worry about releasing polluting fluids into the air or into a water system.

Hydraulic systems

  • Can lift heavier loads

Since the force transmitters for hydraulic systems are non-compressible liquids, they can usually withstand much heavier loads when compared to pneumatic systems. This makes hydraulic systems suitable for applications that require a lot of lifting. This includes elevators, excavators and dump truck lifts.

  • More controllable

Pneumatic systems tend to rely on a quick release of compressed air energy to generate motion. Hydraulic systems, on the other hand, can release energy at a slow and stable pace, giving you more control over the movements.

A great example of this is your car’s braking system. Hydraulic braking systems use the pressure applied to the brake pad turning it into a greater force that slows the vehicle’s wheels. By varying the pressure applied to the pedal, the braking force can be controlled.

  • Suitable for long-term use

Hydraulic systems tend to be a more expensive option up-front. This is because a hydraulic circuit typically operates at higher pressure levels than a pneumatic system. Therefore, it will need to use high-grade materials that won’t break down easily. Unfortunately, such materials are often very costly.

The upside of using expensive materials is that the system tends to last for a long time. If your business is planning to keep a hydraulic system for the long haul, it could save you a significant amount of money on running and maintenance costs.

Hopefully, this gave a little bit more insight on the pneumatic and hydraulic systems. Though they are similar in many ways, they do have key differences that make them suitable for various purposes. Make sure you do your research and choose the power circuit that’s right for you and your business.