In the Market for a Two-Stage Air Compressor?
Here’s What You Need to Know
If you’ve been in an auto body shop recently you may have heard the not-so-inconspicuous hum and rattle of an air compressor. More than likely what you heard was a two-stage air compressor, but why not a single-stage air compressor? Generally, single-stage units are for less demanding operations like home garages or construction job sites. In these settings nail guns or the occasional use of a ratchet gun only require single-stage compressors.
So, why would you need a two-stage air compressor? There are three main reasons:
- Redundancy – If one pump motor fails and or needs service, the other pump motor can continue to operate, avoiding downtime, which is important for any business. Your air flow may be cut in half, but it’s better than shutting down your business while the compressor is serviced.
- Electrical Limitations – What if you absolutely need a 10-15HP compressor but three-phase electrical service is either not available or too expensive to run? A duplex compressor with single-phase pump/motors would be your solution.
- Varying Air Usage – If you’re air needs, CFM, fluctuates throughout the work day, where one minute you’re using a small hand tool and the next a sand blaster, a two-stage compressor is perfect to help regulate air flow. When air consumption needs are low, only one pump motor will operate on your two-stage compressor, but both pumps kick in when demand increases.
If you’re in the market for a new two-stage compressor, here’s what to look for before you commit.
HP (Horsepower)
Definition: One HP is the force needed to lift 550 lbs. one foot in one second.
The CFM (cubic feet per minute) your compressor can generate is actually a critical factor to consider when shopping for a two-stage compressor. But, it’s true that generally speaking, the more HP you have, the more CFM it can produce, so there is a direct correlation that can’t be overlooked. That said, it’s more prudent to shop by CFM, not HP.
CFM (cubic feet per minute)
Every air tool in your shop has a specific CFM requirement—the higher the CFM, the more air volume the tool uses. Keep in mind that if you’re a furniture shop then your sanders will require more air than nail guns.
Take an inventory of CFM requirements for each tool and the number of everyday tools. Next, calculate your necessary CFM, regardless of whether they will all be operating at the same time or not.
Voltage
Single-phase? Three-phase? What’s the difference?
Generally speaking, single-phase electrical is found in residential settings. Three-phase in commercial buildings, manufacturing operations, etc. So, obviously your first consideration of whether to choose a single-phase or three-phase compressor is based on where you will be using it.
Sidenote: Three-phase electricity is considered to be more efficient and therefore could result in less wear and tear on your compressor’s motor.
Keep in mind that electrical codes, voltage and phase vary widely geographically so be sure to check your local building codes and with an electrician before laying out that credit card.
Gallons
How big of a tank do you need for your compressor?
With two-stage compressors tank sizes range from 60 – 200 gallons. The size of your tank should be based on how often the compressor will be in use.
This should give you some insight of what to consider when choosing your next, or first, two-stage compressor.
