How does an Air Compressor work? (Compressor Types) - Tutorial Pneumatics

Summary

This video explains the working principles of different types of air compressors. Focusing on positive-displacement compressors, it details how a reciprocating compressor operates, highlighting its piston-driven mechanism and limitations due to heat buildup. It also covers multi-stage compressors for higher pressure and diaphragm compressors used in specialized industries like food and diving. The video contrasts these with rotary or vane compressors, which offer pulsation-free flow, low noise, and high dirt tolerance, making them ideal for applications like wastewater treatment and vacuum packing.

Takeaways

• 😀 Air compressors consist of an electric motor that compresses air into a storage tank, which can later be released at a chosen pressure.
• 😀 Positive-displacement compressors are commonly used in automation and workshops, where pressure is generated by reducing the volume of a chamber.
• 😀 Reciprocating compressors feature a crankshaft that drives a piston, which moves within a cylindrical housing to compress air.
• 😀 The inlet valve (suction valve) allows atmospheric air into the cylinder, while the outlet valve releases the compressed air during the compression stroke.
• 😀 Air heating during compression is a challenge for compressors, as it can decrease efficiency and create the risk of explosions if flammable substances come into contact with heated air.
• 😀 A single-stage compressor is limited to pressures of about 10 bars (145 psi) due to the risks of overheating and reduced efficiency.
• 😀 Multi-stage compressors, such as two-stage compressors, can achieve higher pressures (over 20 bars or 290 psi) by cooling the air between stages.
• 😀 Large power multistage compressors may use water cooling to prevent overheating during the compression cycle.
• 😀 Reciprocating compressors typically deliver pulsed compressed air, which is why they are often used with an air tank for smoother operation.
• 😀 Diaphragm compressors, like piston compressors, have a diaphragm separating the piston from the air, making them ideal for oil-free compressed air, commonly used in the food industry or for filling diver's bottles.
• 😀 Rotary (vane) compressors use rotating vanes inside a cylindrical housing to create chambers of variable size, delivering pulsation-free airflow. They are quieter, more resistant to dirt, and ideal for applications such as wastewater treatment and dust collection.

Q & A

What is the primary function of an air compressor?

The primary function of an air compressor is to compress air into a storage tank, allowing the air to be released at a chosen pressure when needed.

How do positive-displacement compressors work?

Positive-displacement compressors work by drawing air into a chamber and reducing the volume of the chamber to increase the pressure of the air.

What is the basic operating mechanism of a reciprocating compressor?

In a reciprocating compressor, as the crankshaft turns, a piston reciprocates within a cylindrical housing. Atmospheric air enters during the suction stroke, and high-pressure air is discharged during the compression stroke.

Why is air heated during the compression process in a compressor?

Air is heated during compression because compressing air causes it to increase in temperature. This can reduce efficiency and pose a danger, especially if combustible substances come into contact with overheated air.

What is the limitation of a single-stage compressor regarding output pressure?

A single-stage compressor is typically limited to an output pressure of about 10 bars (145 psi) due to the risk of overheating.

How do multi-stage compressors differ from single-stage compressors?

Multi-stage compressors, like a two-stage compressor, can achieve higher pressures (over 20 bars or 290 psi) by cooling the air between stages to prevent overheating.

What are the advantages of using a diaphragm compressor?

Diaphragm compressors prevent the compressed air from contacting the lubricated piston, keeping it oil-free. They are ideal for applications where clean, oil-free air is needed, such as in the food industry or to fill diver bottles.

What is the main disadvantage of a diaphragm compressor?

The main disadvantage of a diaphragm compressor is the limited elasticity of its membrane, which can reduce the compressor's longevity and efficiency over time.

How does a rotary or vane compressor operate?

A rotary compressor uses adjustable rotary vanes that are mounted on an offset drive shaft. As the shaft rotates, the vanes create chambers of varying sizes, where air is compressed and discharged in a pulsation-free manner.

What are some typical applications of a rotary compressor?

Rotary compressors are used in applications such as wastewater treatment, fish breeding aeration, dust collection, and vacuum packing due to their pulsation-free flow and resistance to dirt.