Air Compressor Type Advantages & Disadvantages
Which Air Compressors type is right for you?
There are several types of air compressors to choose from. Choosing the right type of air compressor is very important for your needs as it will save you money and trouble on the long run. You will learn on this page the advantages and disadvantages of the different kinds of Air Compressors.
It all depends on what you use it for! You will find here a short list of the most popular types of Air Compressors and we will discuss the pros and cons of each one, including some typical examples and ordinary uses.
After reading this page, you should have a fairly good idea what kind of compressor is best for you. The difference between these Air Compressors is both the PRESSURE and the FLOW (cubic meters per minute, or cubic feet per minute). Most common pressure is 7 to 8 bars.
Strap yourself in, because air compressors differ in many ways depending on job demands. Deciding between each option below is a matter of looking at needs, the tools being used, how many users, and budget. The major differences between air compressors are listed and explained below in terms of options, Advantages, and Disadvantages.
Mounted / Unmounted Options
The first major difference between air compressors is mobility, so, naturally, you have a choice between portable air compressors and permanent mount air compressors.
But be careful, because there are major differences when it comes to the Advantages and Disadvantages of each. The type of place where the air compressor is needed will often do the deciding for you.
The best use for mounted air compressors is obvious. Mounted compressors are typically for permanent shops, for working out of a truck, and for longer-term job sites.
Most mounted compressors are electrically powered, but mounted, gas-powered compressors can be found for trucks and job sites as well.
Permanent mount compressors aren't portable, but their list of advantages is long.
- They tend to be less expensive
- Upgrading permanent mount compressors with air filters, water filters, and in-line lubrication is easier.
- There is a much broader selection of electrical power options for mounted units.
- Generally, they are more powerful.
- Generally, they have greater air capacity (CFM output).
Unless you absolutely need a portable compressor, choosing a permanent mount is usually best.
- Not portable.
- More air hose must be run when distance is an issue, and that means some additional cost.
As expected, the real advantage to portable air compressors is their portability. The good news is that portable compressors are versatile, and most jobs that need air compression can be handled just fine by fairly-priced, portable units.
Advantages and Disadvantages for portable compressors are the reverse of the Advantages and Disadvantages for mounted compressors.
There's really no replacement for mobility when you have to have it, and that's where portable compressors shine.
- Portability and versatility.
- No additional air hose needed.
Getting mobility from a compressor is a trade-off, but, as mentioned before, this list of Disadvantages isn't an issue for most jobs.
- They tend to be more expensive (the biggest drawback).
- Upgrading for filtering and lubrication is more difficult, but usually not needed for jobs where portable units are used.
- Most portable units are designed to be electrically powered by standard wall current (but, again, that's usually plenty for mobile projects).
- Air capacity (CFM output) and overall power tend to be less.
- High powered portable units are available, but they are almost always gas-powered, heavy, and expensive.
- The general idea is that if you don't need a portable unit, buy a permanent mount compressor.
- But when mobility is a must, finding a good portable air compressor at a decent price shouldn't be hard.
Air compressors are designed with one or more "stages" (cylinders) where the pistons compress the air.
The "single" in "single stage" means that they only have one cylinder for compressing air. For most air tool jobs (requiring 120 PSI or less), especially jobs around the house, single stage air compressors perform nicely.
For pneumatic tools and jobs that need more pressure (above 120 PSI, generally), multistage compressors measure up to meet the demand. Multistage compressors have two or more cylinders. After air is compressed in the first cylinder, it is passed to the second cylinder for more compression, and so forth.
Multistage compressors create much more heat than single stage compressors, and usually require a radiator. They are needed most when more than one person will be using the same air compressor, and when high demand air tools are in use. Examples: grinders, air nailers, air sanders, and tire changers.
The Advantages and Disadvantages for these options are simple. As the air pressure (stages) and power increase, so do power requirements, cooling requirements, cost, and weight.
Bigger more powerful machines weigh more, need more cooling, cost more, and need more power. The opposite is true of smaller, single stage machines.
If you need a multistage compressor, you'll know by the tools you plan to use with it and how many people will be using it at once.. If you're not sure if a multistage compressor is for you, giving one a "test lift" will usually provide all the missing information you need (make sure to "bend the knees").
Choosing between a gasoline or electric air compressor can be made easier by making other choices first, like choosing portable or mounted. Considering both mobility needs and the demands of the job usually narrow the choice down.
Other considerations play a part as well, such as what type of tools will be used, air pressure needed, and number of users.
Most gasoline compressors are portable, but mounted gasoline-powered compressors for trucks and job sites are available too. There are two basic kinds of gasoline compressor motor designs. Some power electric generators which then drive the cylinder(s) with an electric motor. Others drive their cylinder(s) directly, using a clutch.
If you need a multistage compressor (portable or mounted) it will probably have to be a gasoline unit to meet the power demand. Portable compressors grow heavier with increased power performance. This is especially true since gas compressors tend to be heavier anyway. Portable, multistage, gas-powered compressors can easily grow to be monsters in the 200 lb.+ range.
The real benefit that gasoline compressors offer is an alternate fuel source when electricity isn't an option. That usually means the work site is remote, so the extra noise they make usually isn't usually a problem.
Gas compressors are a great option when electricity isn't available or if portability is an issue.
- Alternate source of power.
- Usability in remote areas.
- Power, in the case of high performance portable machines.
These could be a problem if you don't really need a gas compressor, but the extra hassle pays for itself quickly if it fits your needs.
- Hassle of buying, transporting, and keeping gasoline on hand.
- They tend to be more noisy.
- Powerful, multistage portable units must be gas powered and are heavy.
- A little extra maintenance if you choose to clean the gas tank now and then.
Easy, convenient, and the most common way to run a compressor. Most operate on standard wall current, but the bigger, powerful models offer additional higher-voltage power options. This way, the mounted electric units can keep up with the performance of the powerful portable units, and then some.
Choosing the right electric compressor is very important. As with gas compressors, undershooting your performance needs with an electric compressor will have you replacing your weaker unit in no time. But, if you overshoot on an electrical unit, you may end up paying way more for your power bill than you'd like.
Electric compressors are best for most users when the right one is selected. There are some portable electric units which are best when you need a compact model. One of the biggest drawbacks is having to run lots of air hose, since using extension cords is not recommended
The benefits of electric compressors over gasoline are considerable unless electricity is not available.
- Easy, hassle free power source.
- Best choice for permanent mount compressors.
- Best choice for most jobs
- Portable units are more compact and weigh less.
These usually aren't a problem unless mobility or an alternate power source is needed.
- Additional cost to run extra air hose is recommended to reach a work area, not extension cords.
- Powerful electric units require heavy duty electrical wiring to meet power needs.
- Portable units are less powerful than gas compressors.
- Powerful units can have expensive energy demands.
Like the other options discussed here, the best course of action is to examine your needs. A lot of choices make themselves if you can really pin your needs down first.
This might be the easiest decision to make when buying a compressor. Oiled compressors outperform and outlast oil-less compressors at the expense of extra care and maintenance. If your compressor is going to see a lot of use, oiled compressors are a must, and the required maintenance will be worth the effort in every way.
Oil-Less compressors are only recommended if you're planning to use your compressor now and then. If that's the case, an oil-less compressor will perform well for a long time without extra care.
In an oiled compressor, the cylinders are thinly coated with oil as the machine operates. This makes them much more durable. This also means that, like a car or lawnmower, that the oil must be changed from time to time. Also, oil compressors cost more than oil-less compressors, but it's almost always worth it to go with oil.
Buy an oil compressor if it's going to see a lot of use. Oiled models are absolutely necessary for high power compressors, because a tighter cylinder seal is needed as pressure increases (even more so for multistage compressors).
Checking the oil level with each use and scheduled oil changes are strongly recommended, because an oil compressor will outlast oil-less models by a long shot if cared for correctly.
These advantages of oiled air compressors heavily outweigh the slight inconvenience of the extra care involved.
- Oiled designs make powerful compressors possible.
- Oiled compressors last longer.
- Oiled helps cool the unit.
- Oiled compressors are best under all circumstances, except in the cases of occasional use and budget limits.
Don't let these Disadvantages scare you into buying oil-less unless you really don't see yourself using your compressor much.
- Extra care and maintenance with oil changes/checks.
- Oiled units weigh more in general.
- Oiled units are heavier in general.
- Oiled units are more expensive in general (but they're most always worth it).
These compressors are "permanently" lubricated, usually by coating the the cylinders with something like teflon. You might hear that oil-less models are more advanced. They cut down on care and hassle at first, yes, but the fact is that they wear out, and having to buy a new one is a big hassle. There's just not a good substitute for doing it the old-fashioned way.
But, if you just need an air compressor for jobs here and there that won't demand a lot of pressure (up to about 120 PSI), oil-less might be just the thing for you. They are less expensive (because it takes fewer parts to make them), and they are lighter (from having fewer parts).
Big heads up though--on average, oil-less compressors are not built as well as oiled compressors, but there are a few notably good oil-less designs here and there. So if lighter use is what you're looking for, then an oil-less compressor could be the perfect buy.
Don't let the flashy prices or advertising twist your arm into buying an oil-less design unless you're sure it won't see heavy use.
- Less expensive.
- Oil-less machines are lighter.
- Convenience. Oil-less machines don't need the maintenance that oiled machines do.
Also, don't let the Disadvantages scare you away if an oil-less compressor fits the bill (occasional use).
- Less durable, because the "permanent" lubrication eventually wears down.
- Oil-less compressors run hotter.
- Oil-less units have a power cap, and generally are not as efficient as oiled compressors.
- Oil-less air compressors only offer a good return on their purchase value if you don't plan to use it heavily.
Pressure & Flow Options (Reciprocating Vs. Rotary)
Reciprocating Piston Air Compressors are most often used for high-pressure and low flow applications and scenarios (up to 30 bars), while Rotary Screw Air Compressors are used for continuous applications and scenarios (high flow, 7 or 8 bar)..
Reciprocating Piston Air Compressor
This Air Compressor type uses a piston, which moves inside a cylinder, to compress the air. Reciprocating air compressors, also known as piston air compressors, are perhaps the most popular type of compressor today. These devices increase air pressure using the principle of positive displacement. A chamber is filled with air and then the volume of the chamber is decreased. As described earlier, these work just like internal combustion engines, but backwards and without the spark.
Reciprocating simply means that there's usually a piston that moves back-and-forth, but it can also be a rubber membrane.
Two sets of valves take care of the air intake and exhaust. Piston air compressors are available as lubricated and oil-free, and most of the time with 2 cylinders in V-shape. Very small piston compressors use only 1 cylinder.
They are highly used for general-purpose applications (‘workshop-air’), where the air is used for hand-tools, cleaning dust, painting and others. Together with the rotary screw compressor, it’s one of the most used compressor types.
- Relatively cheap
- Easy maintenance (easy to understand the inner working)
- Suitable for high pressures
- Very noisy! You really need to put this type of compressor in a sound-isolated room.
- High outlet temperature of compressed air
- High oil content in air piping.
Rotary screw compressor (oil-injected or oil-free)
Rotary screw air compressors use two mated helical screws inside a chamber. The air pressure inside the chamber is increased by turning the two screws, essentially reducing the volume. However, the problem with this type of compressor is that it creates a lot of heat and friction. That is why these devices require some sort of lubrication to reduce the temperature and friction, as well as plug up any leaks in the chamber. After the air is collected, the oil must first be separated before it can be used. Air sucked in at one end gets trapped between the rotors, and get pushed to the other side of the rotors (the pressure-side).
There are two basic types of rotary screw compressors: oil-injected and oil-free.
The oil-injected type is most common, because it has a much lower price-tag than the oil-free one (which you should only use if your application requires 100% oil-free air).
- Low noise level. You can just put in in your workshop without wearing ear-protection.
- These are the work-horses of the compressors and can supply a large amount of compressed air.
- Good energy-efficiency compared to piston-type compressors
- Relatively low end temperature of compressed air
- Possible to use energy recovery
- Purchase price is much higher than piston-type compressors
- More complex design, good maintenance very important.
- Minimal air use (per day/week) is required to prevent water condensate forming (will create a lot of problems with rust!)
Scroll compressors are ‘elegant’. They run smoothly, with almost no noise, no vibrations and use a clever design principle to compress the air. However , they are the least used air compressor type.
Scroll compressors compress the air using two spiral elements. 1 is stationary, and the other one moves in small eccentric circles inside the other spiral. Air gets trapped and because of the way the spirals move, gets transported in small air-pockets to the center of the spiral. It takes about 2.5 turn for the air to reach the pressure output in the center.
- Very quiet. Really very quiet!
- Compact. A scroll compressor is very small.
- Simple design, not so many parts
- Low maintenance (hardly any)
- Oil-free design
- Low capacity (flow, liters/minute or cfpm).
- Relatively expensive
- When the scroll-element fails, there’s a very big chance you just have to buy a whole new element.
- The compressed air gets very hot! Much hotter than compared to other types of compressors