In essence, a compressor is a machine that increases any gas’s pressure by decreasing its volume. Similarly, air compressor machines condense normal atmospheric air to increase its pressure. The invention of air compressor machines cannot be attributed to any single person or company.
It was developed and improved gradually over several years before it was perfected. A typical air compressor performs three functions, air intake, air condensation and then air release. An air compressor device’s flow is measured in ACFM (actual cubic feet per minute) or SCFM (Standard Cubic Feet Per Minute). However, the total output produced by the machine is measured in horsepower.
Uses of Air Compressor
Air compressor machines are standard in both industry and household appliances. They are generally responsible for powering heavy tools used in manufacturing and construction, including conveyor belts, jackhammers, grinders and even for drilling. Air compressors are also used to fill gas cylinders used in underwater diving, medical appliances, heating, ventilation, and air conditioning.
Different types of Air Compressor Machines
There are two distinct technologies used in air compressor machines,
- Positive Displacement Compressors
- Dynamic Compressors
1. Positive Displacement Compressors
Positive Displacement Compressors are the most common form of compressors used in the industry. They work by first capturing air in a compression chamber. Once the chamber is full of air, it is gradually decreased in size to compress the air until it reaches the build-in pressure ratio. After the air is completely compressed and pressurized it is released into an outlet.
Some common forms of Positive Displacement Compressors include the scroll compressor, tooth compressor, screw compressors, and the piston compressor.
2. Dynamic Compressors
While the basic functions are the same, a Dynamic Compressors very differently. Instead of reducing the volume of air that has captured in a chamber, dynamic compressors increase the velocity of the air and then block its passage. With a sudden reduction in velocity, the air compresses and becomes pressurized. They can produce very high horsepower which makes them useful for a lot of industrial tasks. Axial and centrifugal compressor are both forms of a dynamic displacement compressor.
Different types of Air Compressor Machines
There are two distinct technologies used in air compressor machines,
- Positive Displacement Compressors
- Dynamic Compressors
- Positive Displacement Compressors
Positive Displacement Compressors are the most common form of compressors used in the industry. They work by first capturing air in a compression chamber. Once the chamber is full of air, it is gradually decreased in size to compress the air until it reaches the build-in pressure ratio. After the air is entirely compressed and pressurized, it is released into an outlet.
Some common forms of Positive Displacement Compressors include the scroll compressor, tooth compressor, screw compressors, and piston compressor.
- Dynamic Compressors
While the basic functions are the same, Dynamic Compressors very differently; instead of reducing the volume of air captured in a chamber, dynamic compressors increase the air’s velocity and then block its passage. With a sudden reduction in speed, the air compresses and becomes pressurized. They can produce very high horsepower, which makes them useful for a lot of industrial tasks. Axial and centrifugal compressor are both forms of a dynamic displacement compressor.
Where are air compressors used?
The earliest use of an ‘air compressor’ are the pre-historic bellows, used for the first time over 4,000 years ago in metallurgy. Not much changed until the industrial revolution, when more advanced compressors became staples in manufacturing and the military. With the growth of suburban life post World War, air compressors became common in household appliances.
Today, air compressor machines have become an essential component of modern life and have industrial and domestic uses. Some of these include:
Construction
The construction industry uses air compressor machines in various ways, depending on the task at hand. Rotary screw air compressors are commonly used in nail guns, jackhammers, compactors, and similar equipment.
Rotary screw air compressors are one of the most efficient ways for large scale infrastructure development. They form the basis for heavy lifting, drilling, demolition, and even building new roads. Air compressors are also found in mobile construction equipment. They do not overheat and can meet the strict safety standards required on a construction site.
Manufacturing
Air compressor machines are at the core of multiple manufacturing processes. From food and beverages to plastics, metal, and pharmaceuticals, air compressors have entirely changed how we manufacture and made possible what was once not.
For plastics and metals, air compressor machines provide a steady airflow for shaping and finishing. In the food packaging industry, air compressors are critical for clean seals and to ensure hygiene.
Agriculture
Agriculture requires the use of heavy machinery that needs to work for hours at an end. Some standard tools and equipment include the humble tractor, sprayers, conveyors, and pumps. All of these use some form of air compressors. Greenhouses and dairy farms also use compressors to provide a better quality of air and stabilize temperatures.
In colder regions such as Canada and Russia, compressed air helps to ‘winterize’ critical equipment and keep it running during harsh weather. It helps to improve efficiency and goes a long way in maintaining the quality of essential tools. Air compressors also power crop sprayers and automatic dairy machinery.
Energy Sector
Air compressor machines are responsible for heavy and very powerful drilling. It has made them quite valuable for coal mining and oil rigs, both of which need safe and efficient drilling. Without air compressors, even the most minor malfunctioning parts can put expensive machines’ functionality and the working people’s lives at risk. They are unique in providing stable output and spark-free deliveries that are imperative for such delicate operations.
Pharmaceutical and the Medical Industry
Air compressors help in delivering oxygen to patients in clinics and hospitals. They are also used in operation theatres since they do not disrupt electronic equipment. In pharmaceutical packaging, air compressors are essential in ensuring air-tight seals and maintaining high hygiene standards.
Domestic use
Air Compressor machines form the basis of several household appliances, including HAVC systems. Basic air conditioning units, heating systems, and even refrigerators and freezers use a compressor.
Other Uses
Air compressor machines are used in dry cleaning and power laundry presses, cleaning guns, and steam cleaners. They are most visibly seen when they are used to inflate car tires and other items. They form the basis of spraying cans and hence make spray paints and similar items possible. In amusement parks, compressed air is used to run roller coasters and animatronics. They are also responsible for air brakes, a powerful braking system used in trucks and buses. Other uses of air compressors can be found in paintball guns, snow machines, pressure washers, sandblasting, air sanders, and air-blow guns.
How Do Air Compressor Machines Work?
The basic principle behind air compressor machines is to collect atmospheric air to reduce its volume and increase its pressure. It allows for more accessible storage of gas and helps to transport it and use it where required. Depending on the kind of technology and compressor, they all work slightly differently to provide the same results – a compressed gas supply at the desired pressure.
Air compressor machines have two important parts, a power source and a compressing system. The power source can be an electric motor, diesel or any other source. The compressor system either be a vane, rotating impeller or a piston.
Reciprocating Air Compressor
A reciprocating air compressor machines use pistons to compress air and store it in a chamber or a tank. There are further variations that include a single-stage and a double-stage version.
A single-stage compressor uses just one piston, while in a double-stage unit, the air is compressed twice and stored at a much higher level. Second-stage compressors are widely used in marine equipment. Due to the high pressure created, they often require higher safety precautions.
Rotary Screw Air Compressor
These can consist of either a screw or a vane air compressor. These require a lot of power to function and have multiple stages of compression. Hence, they can replace a piston compressor by providing huge volumes of high-pressure air. Due to the constant leakage that occurs with this system, they are not suitable for low-volume applications.
Centrifugal Compressor
A centrifugal compressor is a type of dynamic compressor that works at a constant pressure. It is also easily affected by external conditions such as temperature changes etc. The system works by drawing in into a rotating impeller, pushing the air towards a chamber’s centre through centrifugal force—this flow of air results in an increase in pressure. Interestingly, depending on the amount of pressure required, the system can be arranged in several stages to achieve the desired result.
These air compressors are best suited for steady functioning in the industries such as chemical and petrochemical plants, oil extraction plants, and natural gas extraction.
How to Choose the Best Air Compressor Machines
The kind of air compressor machine you have to buy will depend on your needs and specific requirements. However, regardless of the kind of air compressor you are looking for, there are some common features you will need to carefully look at to make the best decision.
Air Filter
Before buying, check the kind of air filter that is installed in air compressor machines. Dry and clean air is necessary to keep equipment and tools protected. Air-dryers help to reduce moisture and contamination, while air filters clean air by blocking dangerous particles.
A flawed air filtering system might gradually damage a compressor tank and even internal parts. In smaller units, air filters are usually disposable, while in larger machines, they are fixed and need regular cleaning. Hence, if you are looking for a unit for industrial use, you will need to check the filter’s quality.
Noise Level
Air compressor machines can be noisy machines and are not always comfortable to work with. Today, you can find all kinds of compressors ranging from quite ones that produce as little as 40 decibels of noise to louder ones that can have more than 92 decibels.
This vast range is a result of the different technologies involved in compressors. For example, a reciprocating compressor has a lot of moving parts which naturally creates friction and noise. However, rotary screw compressors are far more quite.
Having said this, you will still face quite a few limitations. For a start, there are no industry standards to describe a ‘quite’ machine. Also, depending on your need, you might have to use a very loud air compressor. If you have to buy a very noisy unit, use specialized sound dampening pads and rubbers to make things more bearable.
Pumping System
Air compressors come with either a single-stage pump or a double-stage pump. The former compresses gas in a single stroke while the latter compresses air twice. Hence, single-stage pumps have a higher CFM value, but a double-stage pump has a higher PSI. Double-stage pumps are far more efficient, especially when high pressures are required. Thus, when buying air compressor machines, check the pumping system to make sure it meets your needs.
Air Pressure (PSI)
PSI (pounds per square inch) is the unit of measurement for pressure. The higher the pounds per square inch, the higher the pressure of a gas. Light air compressor machines have a PSI of around 90-130. It is sufficient for domestic uses and is suitable for carpenters and hobbyist. These units are also light-weight and mobile.
Even smaller air compressor machines exist with 30 PSI that is mostly used for airbrushing. However, industrial models come with a two-stage system. At the first stage, they can produce up to 150 PSI. In the second stage, they can produce upwards of 200 PSI.
With such a system, it is easier to control the output of pressure and provide sustained pressure. The kind of machine you buy will depend on the PSI you require. Domestic uses will naturally require mobile air compressor machines that you can carry along. If you are buying air compressor machines for use in the industry, you will need more power and a higher PSI.
Standard Cubic Feet Per Minute (SCFM)
Every air compressor machine needs a particular amount of air volume to keep it running. The air volume generated is measured in CFM (cubic feet per minute). It is important to know the SCFM of a machine you are buying as it lets you gauge a unit’s performance. You will find different measurements for CFM based on the speed and size of the pump. At zero pressure, this measurement doesn’t matter because it doesn’t count the pump’s inefficiencies.
Weight of air compressor machines
The weight of air compressor machines naturally affects their portability. Oil compressors are heavy machines due to more features and complex design. However, the oil-free versions are simple and weigh less that makes them easy to carry around.
However, the weight of a unit alone does not determine portability. Many small air compressors can be difficult to carry due to a bulky design. If portability is your primary concern, look at both the weight and design of a machine.
Lifespan
When buying air compressor machines, you need to get the most out of your investment. A cheaper model might break down quickly and cost you far more. It is better to buy a machine that will last you for years to come. However, judging the lifespan of an air compressor unit is complex. It does not always depend on the price or the brand.
You will need to look closely at other features to determine how long it will last. Air compressors with air-cooling systems naturally have a longer life. If they come with an adjustable exhaust, it can protect the unit even further by redirecting exhaust from the working area.
Thermal protection is also necessary and protects air compressor machines by automatically stopping the motor before it overheats. Thermal protection guards the internals of the machine, which can save you tons of money and improve your unit’s longevity.
Tank Size
A compressor tank’s capacity determines how long you can run an air tool before the compressor has to switch on again to create more compressed air. The bigger the tank, the longer a unit can work before making more pressurized air.
Tanks come in varying capacities, from less than 1 gallon to as much as 60 gallons. The size you choose only depends on your usage. For small tasks at home, such as inflating balloons, tires or other equipment, anywhere from 1-3 gallons is more than enough. Suppose you require an air compressor to operate a nail gun or carry out any additional carpentry work. In that case, 8-10 gallons is an excellent capacity to have.
However, professional carpenters and car mechanics require something more long-lasting in the range of 11-25 gallons. It helps to ensure long hours of work without interruption. For light construction work such as grinding, cutting, drilling or painting, a 60-gallon tank should do the job.
Price
The price of air compressor machines can vary depending on the type and the features. The quality of air filter, pumps, and pressure systems all significantly impact the overall price. The total price of an air compressor machine will also include transport and installation costs. Again, this can vary considerably depending on the type and size of the machine. For example, a small hand-held air compressor would not have any installation costs.
You will also need to look at the running costs of air compressor machines. Many latest models are capable of energy efficiency rebates that make them cheaper to use.
Maintenance
The proper maintenance is crucial if you want to use your air compressor machine for a long time. However, the maintenance cost can vary depending on the model and your purpose for the machine. Oiled units need an oil change at least once a year. It can slightly increase or decrease based on how much the machine is used. Even so, regular oil changes can get expensive. However, oil-free air compressors do not need a lot of maintenance. You not only save on frequent oil changes but due to less friction and a more straightforward internal system, there is less need for repair and damage.
Recommendations
We also want to make a couple of recommendations that will help you buy an excellent air compressor machine that is long-lasting and versatile. Make sure to buy a unit that has multiple couplers. It helps you efficiently manage several tasks at a time. It is also better to buy a belt-drive than a direct-drive compressor, as the former are less noisy.
If you are going to use a compressor for hours on end, invest in a compressor with a roll-cage. Air compressor machines are prone to wear and tear when in heavy use, and simple accidents can damage the machine. A roll cage will help to lower the chances of damage and protect the unit.
It is also a good idea to buy a cord wrap. The power cord is the most vulnerable part of the unit and is easily crushed. A broken cord can be very dangerous, and it is better to buy a wrap that will make it easier to carry and store the cord.
Almost every air compressor machine comes with a drain. Still, the old-fashioned cock design is challenging to use and requires pliers. A ball valve design is a better drain system and is far more convenient.
We also recommend that you buy an air compressor that comes with a warranty. These machines can break down quickly when roughly used. You want a sturdy machine, but you also want to work with a company that can provide a warranty on their product. A company that offers an after-sales service will be an even better option. It is especially true if you are buying an expensive air compressor where you might need regular maintenance, repairs, and simple check-ups.
Lastly, buy a machine that is certified by a national body. In the United States, the American Society of Mechanical Engineers or the AMSE certifies compressors. It ensures that the machine is a high-quality product and meets minimum safety standards. There is no reason to buy a non-certified unit, even if it is cheaper.
Conclusion
Before buying a unit, it is better to understand the terminologies and how these machines function. One type of compressor is not better than the other, and it all boils down to your budget, use, and requirements.
Just make sure that the machine you buy is safe to use, meets all necessary industry standards, and does exactly what you want it to do. As a simple rule, buy something better than what you had in mind and make sure it is an energy-efficient model.
