Air compressors have become a valuable tool within many industries over the years. From pneumatic drills to creating snowbanks for winter sports. The number of uses for air compressors may surprise you.
Direct Air created a useful guide and infographic below to give you a better understanding of how they work and what applications each type of air compressor can be used for.
Air compressors do not just have an industrial use, they are a brilliant tool for home use too. Providing you obtain the right machine for the job; you will soon wonder how you ever lived without one.
One of the earliest air compressors dates back to the prehistoric period (source) and was believed to aid in the smelting of tools. Air compressors have come a long way since then and their technology is constantly changing to suit and satisfy demand.
Below is an overview of air compressor models to help you gain an understanding of their mechanics and to ensure you are informed before making a purchase.
Low noise air compressors
Firstly, the most important thing to factor when purchasing any tool is your own safety.
Long exposure to loud noise can cause permanent damage to your hearing, anything over 85dB can be harmful. The level considered safe for air compressors is 60dB. But you can always benefit from decreasing this as much as possible.
Some models decrease the noise level to around 40dB. They achieve this by adding an acoustic chamber for containing the noise. Choosing an electric, rather than a gas-powered machine, will also decrease the noise level.
Even at 40dB, you should wear ear defenders to protect your hearing if exposure is elongated.
Oil-free and oil-based air compressors
All air compressors require lubrication in order to effectively draw in air. To manage this, there are two options: oil-free and oil-based.
Oil-free have a non-stick coating, typically Teflon, within the cylinder to ensure the piston functions properly. These machines are usually more lightweight than their counterparts as they have fewer elements to them. They require less maintenance than oil-based.
Oil-based do require regular oil checks and with added parts to the machines, there are more components that could malfunction.
Unfortunately, this non-stick coating does not last forever and will eventually wear down, meaning you may have to replace the cylinder or the entire machine eventually, depending on how much you use your air compressor.
Overall, with oil-free being more lightweight, less maintenance and most commonly cheaper, they are the type of air compressor best suited to home and DIY use.
Single phase and dual phase air compressors
These are the most common form of air compressors and they operate in fundamentally the same way.
A single phase has one chamber to compress the air. A dual phase air compressor uses two chambers to compress the air twice.
Do not confuse the number of chambers to be the same though as single phase compressors can have two cylinders. This is to compress more air rather than the number of times the air gets compressed.
With these machines, a piston travels downwards causing a change in pressure which forces the chamber door open to draw in air. As the piston travels upwards, it forces air out at a higher pressure. A dual phase will do this but send the air to be compressed one more time in its additional cylinder.
The air is then sent for cooling in a separate storage tank until it is needed.
Between these two, dual phase tends to be used in industries such as pressing factories and vehicle repairs. Choose a single phase for home use as they should suffice for most DIY jobs.
Fixed and variable air compressors
This is all about the speed in which the motor gets its power, this impacts the motor’s frequency.
A variable speed compressor, also known as a VSD (Variable Speed Drive) or VFD (Variable Frequency Drive), can adjust the motor speed automatically in accordance to air demand. This allows the amount of air that is to be compressed to be very closely controlled.
These compressors are highly energy efficient compared to their counterparts as they only use what’s needed. They are more efficient for running costs and have far less impact on the environment. Unfortunately, they are more costly to purchase and maintain.
A fixed rate air compressor sends a continuous stream of power to its motor. In turn, this provides a reliable frequency.
These are more commonly cheaper to purchase and maintain and suit jobs that require a constant stream of power.
Piston compressors, scroll compressors & rotary screw compressors
All the above-mentioned air compressors are piston operated, which is a system for a scroll compressor. The other mechanism that can be used is a rotary screw compressor which operates in a similar fashion but has slight differences.
Below is a quick overview of how these work.
These are a type of piston air compressor but can also be referred to as a reciprocating compressor. Due to their availability and affordability, they are the most common type. The piston travels downwards which causes the pressure in the internal cylinder to decrease as a vacuum is created.
Due to this sudden pressure change, the cylinder door is forced open and air is drawn in. The piston then travels back up, forcing the air out at a higher pressure. This then repeats in a ‘scroll’ pattern, giving it the name.
The great thing about scroll compressors is their ability to cool down quickly and their energy efficiency. However, they contain more complex workings and therefore can be harder to maintain.
Rotary screw compressors
Using rollers rather than a piston, a rotary screw compressor uses the same technology of creating decreasing pressure within the internal cylinder. Rollers, instead of a piston, are placed within the central shaft with one side always in contact with the wall. These then rotate at extreme speeds to create the vacuum.
Rotary screw compressors have a great power capacity and are often cheaper to purchase than a scroll compressor. Although they are easier to maintain, their maintenance checks need to be more frequent and their cooling abilities are limited.
There are many factors that need to be taken into account when choosing the right air compressor for yourself.
Consider how frequent your air compressor will be used and the length of use for each application and this will help you decide between fixed rate and variable speed compressors.
Although it may be tempting to go for the most affordable model, this may come back to burn you later. Look into costs for maintenance and repairs, it is often a better investment paying a little more for a machine that requires less care.
You should also investigate the energy efficiency of potential models, like any power tool, air compressors can use a lot of energy. Not only does this have a negative impact on the environment, it can also have you hit with a high energy bill in the future.