1.1: Fluid Power

We use Fluid Power in all things around us. Almost all mechanical devices are either operated by Fluid Power or produced by Fluid Power. One of the easiest to think of is the brakes of a car to allow the car to stop. When you press the brake pedal in a car, it sends a liquid to the brakes, helping the car stop. In factories, machines might use air to move parts or lift heavy things. Even water flowing from a higher point to a lower point, like in a hydroelectric dam, is Fluid Power at work.

What Is Pneumatics and What Is It Used For?

Pneumatics is a way of using air to make things move or work. Similar to how the brakes are applied in a car, in pneumatics we use air.

Imagine a balloon. When you blow air into it, it gets bigger and can even move the balloon around if you let the air out quickly. This is how pneumatics work. Allow high air pressure to escape to a lower air pressure. 

So, pneumatics is basically using air power to do different tasks, like moving things or making machines work.

Figure \(\PageIndex{1}\): A man using a pneumatic jackhammer to break up asphalt. Original file by Josh Parris. Licensed under the Creative Commons Attribution 2.0 Generic license.

The Basic Components of a Pneumatic System

A pneumatic system typically consists of several basic components:

• Power Unit:
  • Compressor: This is like the heart of the pneumatic system. The compressor takes in air from the surroundings and compresses it, making it pressurized. Think of it as the pump that fills up a balloon with air.
  • Storage Tank: Once the air is compressed, it's stored in a tank called a storage tank or air receiver. This tank holds the pressurized air until it's needed. It's like a reservoir that keeps air ready for use.
  • Pressure Regulator: Uses mechanical devices and pressure fighting against those mechanical devices to open and close a gateway.  When the gateway opens, the air that is at a high pressure can escape to the lower-pressure area. When it does this, the lower pressure area increases in pressure until that pressure is used for work.
• Control Valve: The control valve regulates the flow of pressurized air. It can open to let air flow or close to stop it. By controlling the valve, we control how fast the air can move through the system, which helps control the movement of pneumatic devices. Think of a large and a small doorway. The large doorway allows a lot to flow out of it, whereas a small doorway allows less.
• Actuators: These are the parts of the system that actually do the work. Actuators can be cylinders or motors that use the pressurized air to move things. For example, a pneumatic cylinder might push or pull something when air is directed into it. It's like the muscles of the system that make things move.
• Piping and Tubing: These are the pathways that carry the pressurized air from the compressor to the actuators and back. They're like the veins and arteries of the system, ensuring that air flows where it's needed.
• Power Fluid: A gas, typically air.  Overall, compressed air serves as the primary "fluid" in pneumatic systems, providing the power necessary to operate various pneumatic components and perform tasks. Compressed air is preferred for several reasons:
  • Availability: Air is abundant and readily available in the environment, making it easy to obtain and use.
  • Cleanliness: Air is clean and doesn't leave behind residue or contaminate the environment like hydraulic fluids might.
  • Safety: Air is generally considered safer to use than liquids, especially in environments where there's a risk of leakage or spills.
  • Flexibility: Air is compressible, which allows for more flexibility in controlling the system's pressure and flow compared to liquids.

Figure \(\PageIndex{2}\): A pneumatic schematic showing the basic components of a pneumatic system (ISO 1219).