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 utilize 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 of 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 in cases of a deficit. In a pneumatic system, however, air can simply be drawn from the atmosphere and then purified via a filter.
To better understand the difference between hydraulic and pneumatic system options, let’s start with the basics.
What is Pneumatics?
Pneumatic cylinders are a branch of engineering that uses pressurized gas or air to affect mechanical motion. Today, pneumatic systems are utilized for several devices, from small handhelds to large machines, and serve a range of functions.
Typically, these pneumatic systems are powered by compressed air or inert gas and consist of interconnected sets of components including a gas compressor, transition lines, hoses, gas, air tanks, and standard cylinders.
With these pneumatic cylinders, the airflow is regulated by a manual or automatic solenoid valve, while the pneumatic cylinder transfers energy from the compressed gas to mechanical energy.
Commonly today, pneumatic applications use pressures between 80 to 100 pounds per square inch. With this system, the compressor’s ability to compress gas is limited by the compression ratios.
How Does a Pneumatic System Work?
Pneumatics operate similarly to hydraulics but use gas—usually compressed air—instead of liquid. The air is typically drawn directly from the environment and filtered to remove moisture before entering the system to prevent internal corrosion.
Using a compressible and easily obtainable medium changes the design of pneumatic systems, including adding a compressor, which hydraulic systems do not require.
Some older systems may need oil to lubricate their cylinders, which vaporizes into mist to keep components from wearing. However, newer systems use cylinder and valve seals made from materials like nitrile to avoid using lubricants entirely.
Since pneumatic systems compress air before use, startup can have a slight delay. However, once the gas is compressed, it can operate more quickly.
Pneumatic systems are generally smaller and more straightforward than hydraulic systems and are suited for applications requiring lower pressure, typically operating at 80-100 psi.
Advantages of pneumatic System
- More cost-effective than hydraulics – air is free
- Pneumatic safety – the 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
- The fluid used absorbs excessive force, which means fewer threats of damage to equipment
Applications of Pneumatic System
Pneumatic systems are typically used in construction, robotics, food production and distribution, material handling, medical applications (dentistry), pharmaceutical and biotechnology, mining, mills, buildings, and tools in factories.
Pneumatic systems are primarily used for shock absorption applications because gas is compressible and equipment is less prone to shock damage.
Applications of pneumatic systems include:
- Air compressors
- Vacuum pumps
- Compressed-air engines and vehicles
- HVAC control systems
- Conveyor systems in the pharmaceutical and food industries
- Pressure sensor, switch, and pump
- Precision drills used by dentists
- Air brakes used by buses, trucks, and trains
- Tampers used to pack down dirt and gravel
- Nail guns
- High-pressure bank’s drive-teller tubes
- Manufacturing and assembly lines
- Pneumatic motor, tire, and tools
What is Hydraulics?
On the other side of the hydraulic vs pneumatic systems, debate is the hydraulic system.
Hydraulic systems are used for the control, generation, and transmission of power with pressurized liquids. This technology involves mechanical properties and the use of liquids to function.
With hydraulic cylinders, there are many components involved, including a pump, plus valves to control the force and velocity of actuators. This makes a powerful system, with hydraulic cylinders utilized in industrial applications with 1,000 to 5,000 psi, or more than 10,000 psi for a more specialized application.
Unlike a pneumatic system, hydraulic systems are often large and complex. The hydraulic cylinders require more room, and a container is required to hold hydraulic fluid that flows through the system, making it a less portable option.
With this in mind, hydraulic cylinders also tend to be more expensive, though they can lift and move much larger materials.
How Does a Hydraulic System Work?
Hydraulics systems rely on fluid power: hydraulic oil or water is used to transfer pressure from one point to another. Hydraulic fluid includes mineral oil, ethylene glycol, synthetic liquid, and water.
Hydraulic systems typically include reservoir tanks to store the fluid. Although these systems are bulkier and take up more space, they provide substantially more power.
They usually operate in the 1,000-5,000 psi range, and specialized systems can operate at 10,000 psi or more.
Hydraulic systems vary in complexity and size, but several core components are common to every system. These include:
- A reservoir to store the hydraulic or mineral oil.
- Pipes to transport the fluid.
- A pump with a motor to circulate the fluid.
- Valves to control the speed, direction, and pressure of the hydraulic fluids.
- An actuator that converts the fluid’s energy into mechanical force.
Advantages of a Hydraulic System
- 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
Applications of Hydraulic System
Due to the risk of potential hydraulic oil leakage from faulty valves, seals, or hoses, hydraulic applications do not apply to anything that would be ingested, such as food and medical applications. They are used in a variety of everyday machine applications:
- Elevators
- Dams
- Machine tools: hydraulic presses, hoppers, cylinders, and rams
- Amusement parks
- Turbines
- Dump truck lift
- Wheelchair lift
- Excavating arms for diggers
- Hydraulic presses for forging metal parts
- Wing flaps on aircraft
- A hydraulic braking system in cars
- Lift cars using a hydraulic lift
- Jaws of life
Pros And Cons of Hydraulics vs. Pneumatics
In 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.
What is the Difference between pneumatics and hydraulics?
The biggest difference between the two systems is what substance you use to operate them. Pneumatics uses gases, and hydraulics uses liquids. Both have many practical applications, and it is up to the design team and engineers to make the machines as to which system is will be best.
Because of this primary difference, some other aspects of 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 in cases of a deficit. In a pneumatic system, however, air can simply be drawn from the atmosphere and then purified via a filter.
Best Uses for Hydraulics and Pneumatics
Pneumatics
Pneumatics are typically used in factories, construction, mills, buildings, and technology by using a central source of compressed air for power supply. Medical applications of pneumatics are also widespread, including a dentist’s heavy-duty drill.
Practically everything could run pneumatically, including all means of transport. The small tube in a bank’s bank teller operates pneumatically from a source of high-pressure compressed air.
Hydraulics
Hydraulics has many uses in everyday life and most of them are applicable to machines. Hydraulics are used, for example, in the braking system of a car.
They only require a small amount of force when the driver applies the brakes, but a greater force is already generated to stop or slow a car because it acts equally on all 4 brake pads.
Hydraulic applications are also found in hoists such as wheelchair lifts, excavator arms on machines such as excavators, hydraulic presses for forging metal parts, and wing flaps on airplanes. Obvious applications of hydraulics are with heavy equipment.