pneumatic air compressor

In the modern world of pneumatics, compressors are essential to the operations of factories and workshops around the globe. Air compressors are a relatively new invention in the context of machine age history.

Before the introduction of air compressors, many tools got their power from complicated wheels, belts, and other significant components. This machinery was heavy, massive, and costly and perhaps not out of reach for many small operations. Today, pneumatic air compressors are available in many shapes and sizes, and you can find them in large shop floors, auto workshops, and even garages. In this guide, we are going to look at pneumatic air compressors and how they work.

What Are Air Compressors Used For?

Pneumatic air compressors can be usedfor a wide range of tasks. They can supply air for filling up objects like tires or even supply power for operating tools. Some of the devices that run well with pneumatic air compressors are:

• Grinders
• Nail guns
• Spray guns
• Senders
• Staplers
• drills

From AC units to drills, many versatile air-powered tools and machines are responsible for the shelter, comfort, automation, and efficiency of everyday life. The compressors themselves are more lightweight and compact than other centralized power sources. They are also durable, require less maintenance, and more comfortable to relocate than other old-fashioned machinery.

Piston Air Compressor Functionality

So how does a pneumatic air compressor get air? For those that operate with pistons, it involves two parts, which are raising the pressure and reducing the volume of the air. Most compressors use reciprocating piston technology

Pneumatic air compressor parts

• An electric or gas motor
• An inlet and a discharge valve used to draw in and release air
• A pump to compress the air
• A storage tanks

The compressors suck in air and create a vacuum to reduce its volume. The vacuumforces the air out to the chamber and into its storage tank. After the storage tank reaches its maximum air pressure, the compressor turns off automatically. The process is called the duty cycle. The pneumatic air pressures turn on automatically when the pressure drops below a specific number.

Air compressors don’t need to have storage tanks. This is why there are a few smaller options in favor of portability.

What Is Air Displacement?

Air displacement is the key to each pneumatic air compressor. To compress air, the internal mechanism inside the compressor move to push air through the chamber. There are two types of displacement used:

1. Positive displacement

Most air compressors use this method, in which the air is pulled into a chamber. There, the machine reduces the volume of the chamber to compress the air. After that, it is moved into a storage tank and saved for future use.

2. Dynamic displacement:

Also called nonpositive displacement, this method uses an impeller with rotating blades to draw air into the chamber. The energy created from the motion of the blades builds up air pressure. Dynamic displacement can be used with turbo compressors since it works quickly and generates a large volume of air. Turbochargers in automobiles often use dynamic displacement air compressors.

The Mechanics of a Pneumatic Air Compressor

The way pneumatic compressors work sometimes varies according to design. Piston based air compressors can sometimes have one of the two types of compression cycles:

1. Single-stage

The piston compresses the air in just one stroke. A stroke is one full rotation of the crankshaft driving the piston.

1. Two-stage

The first piston compresses the air before moving it to a smaller cylinder, where another piston compresses it further. This way, the compressor generates higher pressures.

For many single-stagepneumatic air compressors, the pressured pressure limit is 125psi. When this limit is reached, a pressure switch automatically goes off to stop the motor and the production of compressed air. In most cases, you don’t have to reach that pressure limit, so many compressors set air lines to a regulator. The regulator helps you input the appropriate pressure level for a given tool.

When the specific pressure is reached, the regulator automatically shuts off the pump at any point of its cycle, which means the piston can be halfway through the strokes, with pressurized air in the chamber, when it stops. This air can put extreme pressure on the starting circuit, which needs more power to start the motor. An unloader valve is a simple addition that releases the trapped air to avoid this kind of problem.

What Is a Reciprocating Piston?

The parts of a reciprocating piston involve the following:

• Crankshaft
• Connecting rod
• Cylinder
• Piston
• Valve head

The reciprocating piston works similarly to a combustion engine in a car. The crankshaft rod raises the piston in the cylinder and pushes air into the compression chamber, decreasing air volume and increasing the pressure. The piston closes, forcing the compressed air into the storage tank. The piston then again opens to draw in more air, and the process starts over.

Compressors that uses pistons tend to be louder than other designs because of the way the machine components operate and generate friction. However, bet technologies and advancing designs are bringing dual and multi-piston models that can make things quitter by splitting up the workload.

In several heavy-duty industrial applications, a piston compressor just doesn’t cut it. For the higher pressures needed for complicated pneumatic and high-powered tools, professionals tend to choose rotary screw air compressors

However, while the piston air compressor uses pulsation and alternating nature of the piston mechanic, a rotating screw pneumatic air compressor is continuous. A pair of rotors mesh together to pull air in and compress it as it moves through a spiral. The rotary motion moves the air through a chamber and exits. Fat rotational rates can reduce leakage.

Many compressor types need you to take measures to minimize vibrations that can damage the machine. However, most rotary screw air compressors offer even, vibration-free performance.

Rotary screw air compressors can vary widely, with rates from 10 (CFM) to those in 4-5firgure range control schemes. They include the following:

1. Stop/start

This approach either provides power to the motor, or it does not, depending on the application.

1. Load/unload

The compressor is powered continually, with a slide valve that reduces the tank’s capacity when a specific compression demand is established. This type of scheme is more common in factory environments, and if it involves a top timer, it is called a dual-control system.

1. Modulation

Modulation also uses a sliding valve to adjust pressure by throttling/closing the inlet valve, matching the compressor capacity to the demand. These adjustments are less effective on rotary screw pneumatic air compressors than other types. Even if it is set to a zero capacity, the compressor would still consume about 70% of its full power load. Moreover, modulation is applicable for operations in which frequently stopping the compressor is not optional at all.

1. Variable displacement

This control scheme adjusts the volume of air that is sucked into the compressor. In rotary screw pneumatic air compressors, this method may be used alongside modulation inlet valve to improve pressure control accuracy and efficiency.

1. Variable speed

Variable speed is an efficient way to control a rotary compressor’s capacity though it may respond differently with different types of air compressors. It varies the speed of the motor, which affects the output. This equipment tends to be more exquisite than other designs, so it may not be appropriate forparticularly hot or dusty work environments.

One of the essential things to know aboutPneumatic air compressor maintenance is how lube works. When you are looking at oil pumps, you’re dealing with two categories:

1. Oil-lubricated air compressors

In this design, oil splashes onto walls and bearings inside the cylinder. This method is also called oil-flooded lubricants and tends to be more durable. A piston ring is a piece of metal on the piston that helps to create the seal inside the combustion chamber. This ring can help keep oil out of the compressed air, but sometimes it can still seep into the tank

2. Oil-free air compressors

Oil-free pumps receive extraordinary lasting lubrication that eliminates the need for oil. In many industries where contamination is not an option; for instance, breweries, food production, andpharmaceutical manufacturing, oil-free pumps are the best option. They ensure that no oil contaminates the air they use in their product or process.

Oil- flooded pumps are a bit of a mixed bag. For power tools that need lubrication, the presence of oil in the air stream can be advantageous. For machines that need oil, an inline source can distribute oil in even amounts. Many tools, however, can stop working correctly when even minute quantities of oil are present in the air stream

However, for painting or woodworking, oil can interrupt the entire process. It may keep coatings from drying or finishing evenly. Airborne oil can corrupt the surface of wood projects.

Luckily, there are tools to prevent oil from entering the tank, like airline filters and oil separators. Still, when oil-free air is contrary to operation, oil-free air compressors and their permanent lubrication is the best option.

Air Compressor Power Ratings: What Is CFM?

When we talk about power in a pneumatic air compressor, we generally speak in terms of horsepower. Still, there are several other ways to determine how much pressure a machine can produce. We usually use cubic feet per minute (CFM) to discuss the rate and volume by which a tool compresses air. But the rate at which air enters the cylinder is influenced by heat, humidity, and wind in the surrounding atmosphere.

To consider these external and internal factors, pneumatic air compressor manufacturers use standers cubic feet per minute (SCFM),which combines Cubic feet per minute with those outside factors of pressure and humidity.

Another rating that you might notice is displacementCFM, which looks at the efficiency of the compressor pump. It receives information from the revolutions per minute (RPM) of the motor and the volume of air the cylinder can displace. This number is more of theoretical measurements, while on the other hand, you can also measure CFM in terms of delivered air, or how it is removed. This number is called CFM FAD, which means free air delivery, and is more critical for measuring delivery to specific tools.