Hydraulic & Pneumatic Systems – Understanding The Similarities & Differences

Hydraulic & Pneumatic Systems - Understanding The Similarities & Differences

Hydraulic and pneumatic systems both use kinetic motion to move heavy loads. Hydraulics use confined water or oil, and pneumatics use a confined gas, typically air, to generate kinetic motion to drive cylinders and rams. Motion and pressure are converted and multiplied through confinement and precise direction into an intense push.

While the two processes may appear very similar, there are several important differences in how they operate in practice and the tasks they can be used for.
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Hydraulic Power: Pros & Cons

Hydraulics use liquid under pressure to create movement the instant a trigger cylinder is depressed. A pump pressurises hydraulic oil to high levels of PSI (pounds per square inch), allowing hydraulics to lift, suspend, and push far heavier loads than similarly sized pneumatic systems. For that reason, hydraulics are commonly found in cranes, industrial presses, loaders, vehicle maintenance platforms, diggers, and saws.

A hydraulic push system is less energy-intensive than a pneumatic one, as more kinetic energy is translated directly into confined force, thanks to the sealed hydraulic liquid. Hydraulics are better at actuating, too, as the flow of liquid into the system is easier to regulate to a steady pace. The smaller, sealed nature of hydraulics also means that they can feasibly be transported by vehicle and used in difficult environments, such as underwater or in bad weather, with the right adjustments.

However, hydraulic machines often generate intense heat, vibration, and pressure as they do so. Hydraulic machines run a higher risk of outside contamination and breakdown. Hydraulic oil is also toxic, difficult to work with, and highly sensitive to environmental factors.

For this reason, hydraulics are rarely used for medical applications or in food preparation. Hydraulics also take longer to power down and reset than pneumatic mechanisms, as the hydraulic fluid used must be returned to a reservoir by valves and a reverse motor pump.

Pneumatic Power: Pros & Cons

Pneumatics use compressed air to generate bursts of movement by pushing cylinders. They can be powered by both finite (canned) air supplies and renewable compression intakes. The compressed air is released from a reservoir, equalising pressure and generating motion. Pneumatics can generate equal levels of PSI to hydraulics, but this usually requires larger, slower, static pneumatic systems.

The process is more energy-intensive than hydraulics, due to kinetic energy generated by the compressor being wasted as heat. Pneumatic systems also take longer to activate, due to the time it takes to generate and release compressed air. The airflow is less predictable, as well, meaning that they’re not great for applications that need an exact, steady flow of motion. Despite these drawbacks, pneumatics can prove more efficient when working with tasks that require less intense, more precise applications of short-term pressure.

They’re also inherently safer than hydraulics. There’s no risk of toxic contamination, and pneumatic transfer creates far less of a risk of overpressurisation. Pneumatic machines are also considered to be slightly more durable and robust than their hydraulic equivalents.

They’re ideal for heating systems that require the slow transfer of air, machines used with the human body (such as dental drills), low-pressure, low-weight transfer mechanisms (such as pneumatic postal tubes), power tools that require short, intense bursts of motions (such as nail guns), and musical instruments (such as pipe organs).

How Do I Choose The Right Option For My Application?

It depends on the task you want to complete and the risks you’re willing to take and mitigate. If you’re looking at a high-pressure, heavy load to be moved in an industry such as construction or vehicle maintenance, a hydraulic solution might be the better option. If you need smaller, less stable, yet intense and powerful bursts of motion, a pneumatic system might be for you.

You’ll also need to factor in the risks of using high-temperature, high-pressure hydraulic oil, and establish maintenance schedules for each option when budgeting and building your system.

Hydraulic & Pneumatic Systems From Hydrastar

Whether your application requires a hydraulic or pneumatic system, Hydrastar is ready to give you the advice you need to build the machinery that’s right for you. Ask us today about our dedicated components and fully-integrated systems.

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