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    Difference Between Hydraulics and Pneumatics

    Difference Between Hydraulics and PneumaticsHydraulics and pneumatics are frequently discussed in fluid power applications. Two different power circuits are similar in many ways, including the use of fluid to channel mechanical energy and their execution, terminology, and components. Similarly, both systems need a specific type of pump and some valves for velocity and force control. As a result, their differences reveal how and where each can be most useful to you.

     

    What is Pneumatics?

    According to fluid dynamics and pressure, pneumatics is a branch of engineering that uses pressurized gas or air to affect mechanical motion. When it comes to the field of pneumatics, it has evolved from small handheld devices to large machines that serve different purposes. As a general rule, pneumatic systems use compressed air or inert gases to power them up. In addition to a gas compressor and transition lines, the system also includes an air tank and hoses as well as standard propane cylinders (atmosphere).

    Through a series of hoses, compressed air is delivered from the compressor. A solenoid valve controls the air flow, and a pneumatic cylinder converts the compressed gas’s energy into mechanical power through the pneumatic cylinder. Cylinders, air motors, and other pneumatic devices are powered by a centrally located, electrically powered compressor. On/Off switches or valves control pneumatic systems.

    550 to 690 kPa is the most common pressure used in pneumatic applications in industrial settings. In receiver tanks, compressed air is stored and then sent to its final destination for use. Compression ratios restrict the compressor’s capabilities to compress the gas.

    Difference Between Hydraulics and Pneumatics
    An illustration of the basic components of a pneumatic system (Reference: library.automationdirect.com)

    Applications of Pneumatics

    There are a variety of industries that use pneumatic systems. Some of the most common include construction, robotics and food manufacturing, and distribution, as well as material conveyance. As a result of the compressibility of gas, pneumatic systems are originally utilized for shock absorption.

    Various applications of pneumatic systems are:

    • Vacuum pumps
    • HVAC control systems
    • Air compressors
    • Compressed-air engines and vehicles
    • Pressure sensor, switch, and pump
    • Air brakes utilized by buses, trucks, and trains
    • Conveyor systems in pharmaceutical and food industries
    • Precision drills used by dentists
    • Nail guns
    • Tampers utilized to pack down dirt and gravel
    • Manufacturing and assembly lines
    • High-pressure bank’s drive-teller tubes
    • Pneumatic motor, tire, and tools

    Difference Between Hydraulics and Pneumatics
    Various applications of pneumatic systems in industry (Reference: smcworld.com)

    Advantages and Disadvantages of Pneumatics

    Because of the system’s reduced cost, flexibility, and superior safety levels, pneumatic systems are preferred over hydraulic systems. Because they provide a very clean environment for businesses like biotech, dentistry, pharmaceuticals, and food providers, pneumatic systems are ideally suited for applications that require no danger of contamination. The technology can move goods swiftly because it uses clean, dry compressed air. The straight and basic form reduces maintenance and eliminates clogging. Installing and transporting pneumatic systems is simple. They are dependable and have a low initial setup cost because they work with low-pressure and affordable components, lowering operating costs.

    Because the compressed air is pulled from the surrounding atmosphere and purified, there is no need for a container to keep it (optional). Standard cylinders and other components are used throughout the system. The air or gas utilized in a pneumatic system is usually dry and moisture-free to avoid causing problems with internal components.

    Because of the high flow rates of the air compressor, pneumatic systems allow cylinders to move quickly. Air is incredibly nimble, and it can readily and quickly move through pipes with little resistance. Pneumatic systems come in a wide range of sizes, from little to large. Because no exhaust is emitted into the atmosphere, the pneumatic systems are clean and pollutant-free. The pneumatic system is more adaptable because its simple design and control enable operators to alter the system rapidly and without causing environmental damage.

    Because air is cheap, plentiful, and easy to collect and store, pneumatic systems are less expensive than hydraulic systems. Because gas is compressible and the equipment is less susceptible to shock damage, pneumatic systems have a long operational life and need less maintenance. Gas absorbs excessive force, unlike hydraulic systems that employ liquids to transfer force.

    Pneumatic systems provide a number of advantages, one of which is safety. When compared to the explosion or fire threat of pressurized hydraulic oil, pneumatic systems have a very low possibility of catching fire. It also requires less maintenance because filters are rarely replaced.

    Because pneumatic systems do not generate as much force as hydraulic systems, it is critical to establish the amount of force required for your application. Because pneumatic systems do not have the same force potential as hydraulic systems, they should not be used for lifting or moving heavy weights. Because compressed air is subject to air pressure changes, movement while moving or lifting loads can be jerky or spongy at times. To create the same force as a hydraulic ram, a larger cylinder is required. Because of the amount of energy wasted through heat produced while compressing air, pneumatic systems are more expensive than hydraulic systems in terms of energy expenses. Another major issue with pneumatic systems is the noise they produce. It is the obligation of the owners to protect their staff from hearing loss if hearing aids are utilized.

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    What is Hydraulics?

    The mechanical properties of gases are the subject of pneumatics, a discipline of physics or technology. Pneumatics is a field of fluid power that uses gas as a fluid. Compressed air and nitrogen are the two main types of gases utilized in pneumatic systems.

    Compressed air is a blend of all the gases found in the atmosphere. Compressed air is the most extensively utilized fluid for pneumatic systems due to its infinite supply and ease of compression.

    Difference Between Hydraulics and Pneumatics
    An illustration of the basic principle of hydraulics (Reference: smithshydraulic.com)

    Applications of Hydraulics

    Hydraulic applications do not refer to anything that might be eaten, such as food and medical applications, due to the risk of possible hydraulic oil spills from malfunctioning valves, seals, or hoses. They’re employed in a range of common machine applications, including:

    • Elevators
    • Machine tools: hoppers, hydraulic presses, cylinders, and rams
    • Turbines
    • Dump truck lift
    • Excavating arms for diggers
    • The hydraulic braking system in cars
    • Dams
    • Wheelchair lift
    • Hydraulic presses for forging metal parts
    • Wing flaps on aircraft
    • Lift cars using a hydraulic lift
    • Amusement parks
    • Jaws of life

    Difference Between Hydraulics and Pneumatics
    Various applications of hydraulics systems (Reference: goldhydraulics.com)

     

    Advantages and Disadvantages of Hydraulics

    Due to the incompressibility of liquids, hydraulic systems are better capable of transferring larger loads and producing stronger forces. Hydraulic systems serve multiple functions at once, such as lubrication, cooling, and power transmission. Hydraulic machines use higher pressures (1500 to 2500 psi) to generate more force from small-scale actuators. It is critical to select a suitably sized component to match the flow when using a hydraulic system.

    Hydraulic systems are more complex and larger than mechanical systems. Hydraulic oil, for example, is viscous and requires more energy to move. A tank is also needed to store the oil so that the system can draw from it when the oil supply is low. Because power must be included in the machine, the initial expenses are higher than with pneumatic systems.

    Any leakage in a hydraulic system might lead to major issues. Due to the significant potential of hydraulic oil leaks from broken seals, valves, or burst hoses, this system is not suitable for food applications. At each location, proper plumbing techniques, preventative and routine maintenance, and having the right materials on hand are required to reduce potential leaks and rapidly resolve any difficulties. Finally, pneumatic devices are best suited for low-scale engineering and mechanical activities, whereas hydraulic systems are better suited for applications requiring more force and heavy lifting.

     

    Significant Differences Between Hydraulics and Pneumatics

    The distinction between pneumatics and hydraulics is the medium via which power is transmitted. Pneumatics use a gas that is easily compressed, such as air or pure gas. Hydraulics, on the other hand, rely on generally incompressible liquid media such as mineral oil, ethylene glycol, water, synthetic varieties, or high-temperature fire-resistant fluids to transmit power.

    Some other elements of these two power circuits follow suit as a result of this major difference. Pneumatics uses pressures of 80-100 pounds per square inch in industrial applications, while hydraulics uses 1,000-5,000 pounds per square inch or more than 10,000 pounds per square inch in specialized applications.

    Furthermore, a tank would be required to store the oil from which the hydraulic system may draw in the event of a shortage. However, with a pneumatic system, the air is simply collected from the atmosphere and filtered using a filter.

     

    Optimizing Strengths

    Pneumatic systems are known for their ease of design and inexpensive startup costs. This is due to the fact that air-operated circuits operate at low pressure, and components can be manufactured of low-cost materials, reducing secondary machining costs and processes.

    On the other hand, because hydraulic circuits demand a power unit that should be part of your machine, this isn’t something you can’t expect from them at first. As a result, if you’re looking for a low-cost way to get started, air circuits might be the way to go.

    In the meanwhile, in the long run, cost situations will be different. In terms of operational costs, pneumatic circuits could be 5-10 times more expensive.

    To compress atmospheric air into its typical working pressure, it appears that tons of horsepower are necessary. As a result, air motor components are extremely expensive to operate. In the case of hydraulics, the higher initial cost is frequently offset by lower operational costs due to higher efficiency. Hydraulic machines use higher pressures, ranging from 1500 to 2500 psi, to generate more force from small-scale actuators.

    When a manufacturing company has a lot of hydraulic machinery, it’s a good idea to set up central power units to get the most out of them. Machine noise will be decreased significantly, machine uptime will be increased, and backup pumps will be provided in the event that a functioning pump fails.

    In comparison to their hydraulic equivalents, pneumatic systems are easier to maintain in terms of housekeeping. Because the force transmitter is atmospheric air, air-operated circuits are cleaner. There will be no problems if there are any leaks.

    However, this can be extremely costly, as providing air to a common portable blow-off nozzle and maintaining 100 psi requires roughly five compressor horsepower.

    As a result, even if hydraulics housekeeping is a problem, the problem can be resolved by taking the appropriate steps. Hydraulic leaks can be minimized with proper plumbing practices, preventive maintenance, and suitable materials.

     

    Best Uses for Hydraulics and Pneumatics

    Pneumatics

    By utilizing a central supply of compressed air for power, pneumatics are commonly employed in industrial setups, construction, mills, building, and technology. Pneumatics are also commonly used in medical applications, such as a dentist’s high-powered drill. Pneumatics could be used to power almost anything, including transportation. That small tube in a bank’s drive-teller works using pneumatics and a high-pressure compressed air source.

     

    Hydraulics

    Hydraulics have a wide range of applications in everyday life, with the majority of them being machine-related. Hydraulics, for example, is used in a car’s braking system. They only require a tiny amount of effort when the driver applies the brakes, but a larger force is already generated when a car is stopped or slowed down since it operates evenly on all four brake pads.

    Hydraulic uses can also be found in wheelchair lifts, hydraulic presses for forging metal parts, excavating arms on machines such as diggers, and aircraft wing flaps. Hydraulics are most commonly associated with large machinery.

    In what follows, you can see a summary table of the difference between hydraulic and pneumatic systems:

     

    Hydraulic systems Pneumatic systems
    Hydraulic oil is used as the operating fluid. Compressed air is the working fluid.
    Oil may be pressurized to extremely high pressures because it is incompressible. (500 bar or above) Because air is compressible, it can be pressured to lower pressure. (Only up to about 10 bar.)
    Because of the tremendous pressure, the force created is also very high (thousands of tonnes). Because the pressure is low, the force created is also low (up to 1 ton)
    Because of the tremendous pressure, the components are composed of steel and are very heavy. The pneumatic system’s components are lower in weight and constructed of aluminum.
    Oil cannot flow quickly due to its higher viscosity. As a result, hydraulic systems are slower to operate. Air has a low viscosity and can flow quickly. As a result, pneumatic systems are more efficient.
    The temperature of the oil rises as a result of continual recirculation. It operates cooler the harder it runs. The cooling effect is caused by the free expansion of air in cylinders and motors.
    Hydraulic oils are petroleum-based fluids that are combustible and can cause fire danger if not handled properly. There is no risk of fire. As a result, pneumatic equipment is preferred within mines with combustible vapors.
    Oil leakage results in a soiled and slick surface. Surroundings that could cause an accident. The environment is kept very clean and dry.
    A pressure relief valve is required because the pump is a positive displacement pump. A pressure relief valve isn’t required.
    Because the hydraulic fluid is a lubricant, there is no need for a separate lubrication system. A lubricant is required. In the lubricator, oil is combined with compressed air before being sent to the system.
    CNC, machine tools, earth-moving machinery, vehicles, aircraft, and other applications Material handling systems, hand tools, mining operations, automation, cars, and other applications.

     

    Conclusion

    Hydraulic systems are best used for large lifting applications like the jaws of life, elevators, aviation wing flaps, and hydraulic presses and arms in heavy equipment because they work at greater pressures (1500 to 2500 psi) and generate more force from small-scale actuators. Pneumatic systems are recommended for moving or processing products, particularly food and pharmaceuticals, because there is no risk of contamination from broken pipes or oil leaks.

     

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