Two-Stage Air Compressor Buyer's Guide

How To Pick The Perfect Two-Stage Air Compressor

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By Melissa C.

Air Compressor Expert

If you've ever worked in manufacturing or visited your local garage, you might have heard a rattling hum. That's the sound of power.

A two-stage air compressor to be more exact. To pick the perfect two-stage compressor, you've got to know what to look for.

Don't worry-we can help you pick the right 2-stage compressor for the job.

HP (Horsepower)

One Horsepower (hp) is the force needed to lift 550 lbs. one foot in one second. If you ask Tim "The Tool Man" Taylor, he'd invariably tell you, "It needs more power." The CFM (cubic feet per minute) the compressor can produce is most important.

Typically though, the more horsepower, the more power the compressor will have and the higher CFM it can produce. This isn't a muscle car so don't shop by horsepower. Shop by CFM needs instead.

CFM (Cubic Feet per Minute)

CFM is the most important factor in determining what air compressor works for you. Every air tool has a CFM requirement. The higher the CFM, the more air volume the tool uses.

Many garages will power multiple air tools off one air compressor. Regardless of how many tools you are running simultaneously, you will need to estimate how much CFM you will need to power at any given time.

Total the CFM of tools in use and make sure the compressor can handle the workload. Tools that require constant power, such as grinders or sanders, will require more CFM than tools which need sporadic power, such as nail guns.

Voltage

The main difference in voltage and single vs. three-phase is where you will be using your compressor.

In a residential setting, you will be dealing with single phase.
Make sure you know what type of wiring you are dealing with before buying a compressor. With many different types available, you'll find one to fit your needs.

With competitive price and timely delivery, kapa sincerely hope to be your supplier and partner.

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Three phase electricity is found mostly in industrial settings. Three phase power is considered more efficient and will result in less wear and tear on your motor. Voltage and phase vary by location so consult your local codes and electrician before purchasing.

Gallons

The size of the tank on a two-stage air compressor is measured in gallons. They can range from 60 - 200 gallons. The size of tank you need is predicated on the how often the compressor is in use.

Start-stop air compressors run until the tank is full of compressed air. As you use air tools, the PSI from the tank is depleted. Once this reaches the low setting, the compressor turns back on and refills. If your compressor is starting and stopping too frequently you run the risk of overheating which can damage the pump.

Constant-run air compressors run 100% of the time but regulate the air output as needed.

Style

Two-stage air compressors come in two styles: horizontal or vertical.

Your space requirements or limitations will determine which style to buy. If you don't have a wide area to run one in, get a vertical compressor.

Likewise, if you are storing the compressor up high and have height limitations, choose a horizontal model. There is no difference in performance and utility of horizontal vs. vertical compressors of equal power. They are the same machines, just built in different styles.

NEXT: Two-Stage Air Compressor Product Selector

Virtual Air Treatment - How to Get Clean, Treated Air

Looking for ways to treat your compressed air? Whether you're using your compressor for applying a smooth coat of paint to an automobile or using it for powering air tools, air treatment is an important part of doing the job right.

Removing water and contaminants from your compressed air can prolong the life of your air tools and keep your paints clean and dry so they apply more smoothly. Browse our virtual air treatment guide for ideas on how you can improve the quality of your compressed air.

View Our Virtual Air Treatment Guide

By Melissa C.

Air Compressor Expert

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The advantage of multi-stage compressors is better mechanical advantage and efficiency. The mechanical advantage isn't obvious, but it's smoother to design a compressor so that it doesn't compress more than about a 8:1 ratio. So you stack two in a row and design a crank so that the drive motor has a more even load.

The thermal efficiency is improved because it's easier to compress cool air. As you compress the air it heats up. If you compress the air in a single stroke, the compressor has to work against both the compressed air and the extra pressure from the heat. When the compression is spread over multiple strokes, the intermediate air has a chance to cool down a bit, taking less energy for the second round.

Most residential electric service is single phase: 120/240V from the pole transformer, with 'one wire' (plus ground). This is like running a single cylinder engine -- the motor doesn't has a natural direction, and it won't start on its own if it's in just the wrong direction. So there is an extra circuit, capacitor or winding that creates two phase power (a weak extra phase that kicks the motor in the right direction).

Most industrial service is three phase: 208V/415V coming from three wires (plus an optional ground). This is very convenient for running high power motors. With three phases the motor has a natural direction and delivers near-constant torque through the whole rotation for consistent starting, smooth running and low noise. Think of it as a smooth-running V8 or V12 engine.

There is such as thing as two phase power, but it's rarely used. It's like a Harley, uneven power delivery and lots of vibration and noise. Two phase power still needs three wires, and winding motors is a PITA, so it has only disadvantages compared to three phases.

 

For more information, please visit Horizontal Two-Stage Air Compressor.