What Are Compressors?

Compressors are mechanical devices designed and used to increase the pressure of various compressible fluids and gases by reducing their volumes. They are widely used to generate air that powers a range of air tools like abrasive blasting equipment and paint sprayers. Compressors are also used in air conditioning and refrigeration, as well as for gas propulsion through pipelines [1].

Typically, compressors compress gases or liquids. The most common of these gases are air. When used on liquids, a compressor works like a pump. It increases the pressure on the fluid and transports this through pipes. Thus, liquid compressors are intended for pressurising and transporting purposes.

What Are Air Compressors?

Many industries are using compressors to deliver the services they offer to their clients. The compressors they use vary in form, size and configuration. However, the most common of these are air compressors.

An air compressor converts power into energy stored in pressurised air. In most cases, this type of compressor uses an electric motor, gasoline or diesel engine. An air compressor commonly forces more air directly into its storage tank, and this mechanism increases the pressure.

When the pressure in its tank reaches the maximum limit, an air compressor automatically shuts off. The tank then holds the compressed air generated until it is put into use. The kinetic energy of the compressed air, when released from the tank, is used in various applications. When the air inside the tank is released, the pressure is reduced. When it reaches the lower limit, the compressor automatically turns on again, until the tank is fully repressurised.

How do air compressors work?

Air compressors are more powerful than regular tools, and they require no bulky motors. Their portability and versatility make them essential in many factories and workshops, being used in different situations. To choose the right air compressor for a certain need or project, the way these machines work should be understood [4, 5, 6].

Air compressors work in two phases: compression and release. A key to how they work is their air end and gas engine components. The air end is the one that compresses air. It gets atmospheric air into a container called the compression chamber, where it is then forced into a compact space. The forcing of these air molecules closer together is what compresses air. 

During compression, a power source or the gas engine turns electrical energy to kinetic energy and forces the air end to move and then compresses air. This compressed air is what’s used to help a variety of tools to work.

Air compression can be done via either positive or dynamic displacement. With positive displacement, the air is forced into a chamber where the volume is decreased to compress it, and the system needs to attain its maximum pressure. Afterwards, the air from the compression chamber is released to enter into the storage tank with force.

Some air compressors with positive displacement mechanisms are used for industrial purposes, while others are for home projects. Positive displacement is also a term used to describe air compressors that compress air through positive air displacement.

Meanwhile, with dynamic displacement, a rotating blade powered by an engine is used to generate airflow. The air is then compacted to create pressure, and the kinetic energy is stored within the compressor. This is a slight variation from the other system with the use of impellers and rotating blades. Compressors of this type provide energy from the build air pressure because the blades are constantly moving. Dynamic displacement air compressors are typically used in large-scale projects, such as in chemical plants. They can’t be used for DIY activities.

Air Compressor’s General Categories

Air compressors have various types. The main categories according to air displacement mechanisms are as follows.

Positive Displacement

A positive displacement compressor generates power through air displacement. The compressor takes in a sufficient amount of air through its inlet and forces the gas to exit through the device’s outlet.

Dynamic Displacement

A dynamic displacement compressor generates horsepower by using the blades that rotate rapidly to bring in air and then restrict this to create pressure. This mechanism produces kinetic energy, which is then stored as static energy inside the compressor.

Types of Air Compressors

  • Rotary Screw Compressor

Rotary screw compressors are equipped with a rotary-type positive-displacement system. This type of compressor is commonly used in industrial applications. It serves as the replacement for the more traditional piston compressors that use more significant amounts of compressed gas.

The gas compression process in a rotary screw is accomplished through a continuous sweeping motion. This generates a minimal amount of pulsation compared to what most piston compressors are creating. Moreover, rotary screw compressors are significantly quieter and generate lesser vibration compared to piston compressors. They are also among the most popular in the market because they require no or lesser maintenance.

Rotary screw compressors are designed for continuous use and equipped with an internal cooling system that prevents overheating. They are capable of generating power ranging from 5 hp to 350 hp.

  • Reciprocating Air Compressor

Reciprocating air compressors are created with a piston-driven mechanism. They come with pistons that compress and displace the air inside a cylinder to build pressure. This type of compressor has many moving parts that need constant lubrication to smoothen movements. Therefore, they are not suitable for long and continuous use.

The reciprocating air compressors are available in various configurations. These are marketed either as portable or stationary and single or multi-staged. They can also come with internal combustion engines or electric motors.

The smaller reciprocating air compressors can generate 5-30 hp. These are typically used for intermittent duty and a range of automotive purposes. The larger versions of these compressors are usually utilised to handle massive industrial and petroleum applications. These compressors provide outputs that are well over 1000 hp.

  • Axial Compressor

Axial compressors are regarded as dynamic rotating compressors. They are equipped with arrays of airfoils with a fan-like structure designed to compress fluids progressively. These compressors are commonly used in areas that require compressors with compact designs and can provide higher flow rates.

In axial compressors, the compressor’s airfoils are placed in rows and pairs (one is rotating and the other is stationary). These rotating airfoils (commonly referred to as rotors or blades) take charge of accelerating the fluid. The fixed rotors (also dubbed as stators or vanes) are in charge of decelerating and redirecting the fluid’s flow direction. They also prepare the fluid for the next stage’s rotor blades.

The axial air compressors are mainly used in high-speed planes, ships and engines. They are known for their high efficiency rate, and they can generate thousands of horsepower. That’s why they are pretty expensive and used in conducting aerospace research.

  • Centrifugal Compressor

Centrifugal compressors are commonly used in construction sites that require more demanding activities, such as steel manufacturing complex and chemical plants. These devices generate energy by drawing air into the centre of a radial blades-equipped rotating impeller. The air drawn is pushed into the centre by the centrifugal force, and the created movement results in an increase in pressure and generation of kinetic energy.

A centrifugal air compressor can slow and cool the air it draws and directs into a diffuser to generate potential energy. It can also perform a multi-phase compression process that allows the device to produce high amounts of power despite its relatively small size. In most cases, they can generate outputs that are more than 1,000 hp.

Furthermore, a centrifugal compressor requires lesser maintenance compared to the reciprocating or rotary screw variants. Some variants can also produce oil-free air.

How to Choose the Right Compressor

With the many available options in the market, choosing the type of compressor that best suits your needs might not be that easy. To help you in deciding which compressor to get, here are some things you may want to consider.

  • Set your goals.

Before you go out to shop for a compressor to purchase, it is best that you set specific goals. Make a comprehensive assessment of why you need to buy a compressor. Also, try to determine if buying a unit will resolve all the problems caused by not having one.

  • Set your buying criteria.

As soon as your purchasing goals are set, develop a set of realistic buying criteria. Doing this will help you focus your attention on a specific type, size and configuration of a compressor. This can also increase the chances of buying a compressor that best suits your needs.

  • Create a list of available compressors.

With buying criteria in mind, create a list of the available compressor options. You can do this by conducting online research. Limit your search on the products that match your criteria. This will help you avoid buying a compressor that does not suit your needs. List all the top products and include these in your buying options.

  • Narrow your options down.

After finishing the list of the top names and brands of compressors that best suit your needs, try to narrow your list down. Make a comprehensive assessment of the pros and cons that each product has. Select the top 3 options that provide more benefits and look for these when you go out to purchase a unit.

  • Select the best deals offered.

Shop for the top 3 products on your list. However, you can also consider looking for the best deals offered for each product. Go for the unit that is sold at a competitive price and backed by applicable warranties.

Where to Look for the Best Compressors

  • Local dealerships

Local dealerships typically have an extensive collection of compressors. This gives you an excellent chance to find the models that are on your list.

  • Online dealerships

When you search for the best dealerships online, check out sellers with the highest ratings and positive reviews. In addition to the prices of the models you are interested in buying, you should also consider the aftersales offers and the warranties that the dealerships are offering. If you are done collecting the best online deals, you can also compare these with what the local dealerships are offering. Check the overall cost of buying from both sources and opt for the one that allows you to save whilst giving you the most suitable unit.

Adaptive Air Compressors: Tailored Solutions for Your Business

Adaptive Air Compressors is a trusted provider of various solutions specifically tailored to suit our customers’ diverse needs. We offer a wide selection of air compressors and their accessories. We are also engaged in providing our customers with preventative maintenance service plans, site inspections for installing new or replacement of old compressed air systems, and aid and power usage audits.

We, at Adaptive Air Compressors, are committed to providing fast, practical solutions to all your compressed air needs. If you have any questions about our products and the services we offer, call us at (02) 4393 1865 24/7. Let’s arrange a solution that will work best for you.