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 (which is unfortunate because it probably means you’ve had fender bender) or a small manufacturing operation, you may have heard the not-so-inconspicuous hum and rattle of an air compressor. More than likely it was a two-stage air compressor. Why not a single-stage? Generally, single-stage units are for less demanding operations like home garages or construction job sites where the distinctive pop, pop, pop sound of nail guns pierce the air like firecrackers on the 4th of July. Nail guns or the occasional use of a rachet 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 or needs service or repair, the other pump/motor can continue to operate, avoiding downtime. 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 service.
- Electrical Limitations – What if you absolutely need a 10-15HP compressor but three-phase electrical service is either not available or too expensive 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. Smart little boogers, aren't they.
If you’re in the market for a new two-stage compressor, here’s what to look for before you commit.
Definition: One HP is the force needed to lift 550 lbs. one foot in one second.
With all the hubbub made over HP, the CFM (cubic feet per minute) your compressor can generate is actually a more critical factor. 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, and then calculate your necessary CFM, regardless of whether they will all be operating at the same time or not.
Single-phase? Three-phase? What’s the diff?
Generally speaking, single-phase electrical is found in residential settings. Three-phase in commercial buildings, manufacturing operations, etc. So, obviously your first consideration 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.
So, now how big of a tank do you need for your compressor? How many gallons?
With two-stage compressors tank sizes range from 60 – 200 gallons. The size of your tank should be basedon how often the compressor will be in use.
This should give you enough to go when choosing your next, or first, two-stage compressor and enough ammunition to ask intelligent questions.Posted on: August 17, 2015, by : Cameron Ballentine