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How Big of An Air Compressor Do I Need- Let’s Find Out

Purchasing a home air compressor has lots of benefits. First, you no longer need to go to the gas station or the mechanic shop in case you have a flat tire. Again, inflating your sports balls becomes easy and convenient. Other air compressors are good for air-powered tools, and so you can see the benefits are limitless.

The problem comes in choosing the right air compressor for your specific needs. You might feel quite lost if you don’t know what to look for.

One of the most important factors to look out for is size, and in this post, we shall be looking at how to choose the correct air compressor size. Apart from that, we shall go deeper into choosing the right air compressor.

So, Which Size Air Compressor Do I Need?

There is a full range of air compressors when we’re considering the size and its related aspects like shape and pressure level. If you need the machine for work purposes, we’d advise you to go for a heavy duty, robust model that is designed for commercial purposes.

But, if you need something for emergencies only, say inflating a flat tire, go for portable model that’s meant for home use.

Of course, the aspect we’re considering while talking about size is the size of the tank. The bigger the tank, the more the air but that also means that the compressor is more expensive and more difficult to maintain than smaller compressors.

A big air compressor will obviously consume more space, and that’s a factor you need to think about if you’ll be storing the unit in your home.

Most tanks have the capacity of 80 to 240 gallons. Your choice should be based on your needs and your budget of course.

As we mentioned before, to get the right size, just consider the sort of work you’re looking to do. In the event that you need to power several tools at the same time, a big tank will be vital. It’s not just about the degree of power delivered. Picture this – you’re using a small tank to power a number of tools, and suddenly, you’re out of air and have to pause and refill the tank; you can be sure this will take place frequently with a small tank. That is the inconvenience a bigger tank helps you avoid.

Think, also, about the type of tools you need to power. If you want to power tools like brad guns and nailers, you will get by just fine with a small air compressor as such tools don’t consume much power.

Guide for choosing the right air compressor size

Now, let’s go through a step by step guide for getting the appropriate air compressor size. We used experience and logic to come up with this systematic approach for arriving at the right choice and we believe that with it, you will get what suits you.

Step I

Work out your air needs

Your tools came with user manuals that might contain the information on their CFM (cubic feet per minute) requirements. You could also check with your manufacturer for that.

What is CFM?

CFM measures the rate of air flow and is essential in determining the right air compressor size.

Step II

Once you have determined your tools’ air requirements based on CFM, add that up. The table below is an example of the air powered tools you might have along with their CFMs. In our example, the total CFM is 68.

Number of tools

Tool Name

CFM of each tool

Total CFM

3

Impact Wrench, 1/2" Drive

3

9

3

Impact Wrench, 3/4" Drive

7

21

1

Impact Wrench, 1" Drive

10

10

3

Tire Changer w/Inflator

4

12

1

Grease Gun

4

4

2

Oil Pump

4

8

2

Parts Washer

2

4

TOTALS

68

Step III

Consider the duty cycle. That is, how long will the compressor run before needing a refill with air? For instance, it might run 70 percent of the time you’ll dedicate to powering a certain tool with air.

70% of 68 = 47.6 CFM. 47.6 is the CFM figure you’ll be using to pick the appropriate air compressor.

Step IV

Establish the needed pressure levels (in psig). A majority of air-powered tools need around 90 to 100 psig. Some equipment, however, like tire changers, need more, even up to 150 psig. If you’re unsure as to the pressure requirements of your tools, check with the manufacturer.

Step V

Find out the voltage and phase of the power outlet where you will be connecting the compressor. If you have no way of knowing, ask for assistance from a trained electrician. After finding this out, compare it with the voltage requirements of the compressor you’re looking to purchase.

Step VI

What is the size of the compressor’s tank? In most cases, the size of the tank goes hand in hand with the compressor’s CFM. Common tank sizes include 80, 120, and 240; these values are in gallons.

Air Compressor Pump Types and Features

There are 4 main types of air compressor pumps:

  • Piston/reciprocating
  • Rotary screw
  • Rotary sliding vane
  • Centrifugal

1. Piston/Reciprocating Compressors

This is the most popular type. Piston compressors are “positive displacement” in nature and are available in various ranges from fractional to high horsepower.

Wondering what we mean by positive displacement?

That just means that a chamber gets filled with air, and then the chamber’s volume is reduced when the compressor is in use.

Other compressors that are of positive displacement nature include:

  • Rotary screw
  • Rotary sliding vane

Piston compressors normally incorporate the following items:

  • Cylinders
  • Pistons
  • Valves
  • Crankshafts
  • Housing blocks

Pros

  • Low initial cost
  • Simple design
  • Easy to install
  • There’s no oil carryover
  • High efficiency in a 2-stage model
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    Vast range of horsepowers
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    High pressure is achieved

Cons

  • High cost of maintenance
  • Numerous moving parts
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    Foundation might be needed if the compressor is very big
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    Don’t run to full capacity most of the time
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    Too many moving parts

2. Rotary Screw Compressors

A rotary screw compressor fills a void that exists between 2 helical mated screws and their casing. When the screws get rotated, the air volume reduces, thereby increasing the pressure. In most cases, oil is injected into the compression area and the bearing. This oil is meant for lubrication, cooling, and sealing any internal leakages.

Once a compression cycle is complete, the air and the oil have to be separated so the air system is able to use the air.

Pros

  • Simple design
  • Simple installation
  • High efficiency
  • Few moving parts
  • Popular
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    Low/medium initial cost

Cons

  • The airend life is limited and again, airends aren’t field serviceable
  • Shorter overall life compared to other compressors
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    There’s oil carryover
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    Oil-free models have high initial cost

3. Rotary Sliding Vane Compressors

This positive displacement compressor comprises a stator, rotor, and eight blades. The rotor is unconventionally placed with the stator, creating a crescent-shaped part between the exhaust ports and the air intake.

When the rotor makes a complete turn, compression is attained.

Oil gets injected into the intake and along the walls of the stator with the purpose of cooling the air, lubricating the vanes and bearings, and sealing leakage points.

Pros

  • Simple design with easy installation
  • Low to moderate initials costs
  • Low cost of maintenance
  • Airend is field serviceable
  • Airend has a long life
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    Just a few moving parts
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    Low speed of rotation

Cons

  • Oil-injected models have oil carryover
  • There’s hardship with high pressures of more than 200 psi
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    One-stage models are not very efficient

4. Centrifugal Compressors

Unlike the other compressors we’ve looked at, centrifugal compressors are not of positive displacement mechanism. Instead, they utilize impellers spinning at extreme speeds (up to 60000 RPM) for accelerating the air and diffusers for decelerating it.

The process is called dynamic compression, and it employs velocity to build up pressure.

Pros

  • Very efficient
  • High pressure levels, of up to 1200 psi
  • Relative initial cost gets better as the compressor’s size increases
  • Gives lubricant-free air
  • No special foundations needed

Cons

  • High initial cost
  • The monitoring and control systems are somewhat complicated
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    Specialized maintenance might be required

Other Factors to Take into Consideration

Apart from size, there are several other factors you ought to consider, and the most vital ones include these:

Pressure gauge

The pressure gauge needs to be built into the machine. That way, you will be able to view the amount of air pressure you’re putting into items like car and bike tires.

Without a built-in pressure gauge, you might end up overfilling and popping items like balls and tires.

Valve

The air compressor has got to have a long hose, at least 10 ft. so you’re able to reach tires and equipment.

Fuse

First, the plug ought to be made of heavy-gauge materials so it doesn’t break easily. Then, it needs to have a fuse built into it, such that in case of any electric blunders, only the fuse will get damaged and not the unit. One more thing – the fuse should be easily accessible so that if the one you’re using is blown, you get it replaced quickly.

Attachments

Go for a compressor with various attachments, for examples, one for filling up tires, another for pumping sports equipment, and so on.

Power supply

Majorly, there are gas compressors and electric compressors. Though both types are okay, if you’re to go for a gas model, then you better have enough ventilation.

There are gas compressors, as well as electric. Both do the job, but for gas models, you must have adequate ventilation. You want one that has enough tank capacity for your needs, and one that can handle different or multiple tools if necessary. You require looking around for one that is going to fit your needs.

Price

The price tag of smaller models ranges around 50 to 100 dollars. If you want a big model, then you’ll be parting with a few hundred to a few thousand bucks, depending on the features.

The best place to buy an air compressor is Amazon, as it gives you a perfect chance to compare the prices that different sellers are offering.

Final Thoughts

By now, we believe, you have a vivid idea of the size of air compressor you need. Remember, it’s about reflecting on your needs. If you need something for emergencies only, a small, portable, and inexpensive model is perfect. But, if you’re looking to go commercial or if you’re working with too many air-powered tools, then a bigger model is essential.

Click Here to Leave a Comment Below 1 comments
James Anderson - May 31, 2018

It’s great that you’ve mentioned how one should choose an air compressor based on the various attachments that come along with it, as it will identify which things or objects it can be used on. My father is planning to start his own gas station business, and one of the things that he is thinking about would be the air machine. I’ll mention this to him so that he can choose an air compressor that has an attachment for inflating or filling up tires.

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