Choosing the Right Air Compressor…
For many businesses, an industrial air compressor is a critical component of day-to-day operations. In other industries, it serves as auxiliary equipment that supports production by improving efficiency. While it may not be essential to keeping operations running, it plays an important role in reducing production and operational time. By streamlining processes and minimizing delays, an industrial air compressor helps businesses increase productivity, improve workflow, and operate more efficiently.
Whether you're replacing an older unit or purchasing your first compressor, choosing the right model can improve productivity, reduce operating costs, and ensure your equipment performs at its best. With so many options available, understanding the differences between compressor types, pressure ratings, and airflow requirements is essential before making your investment. How do you know which is the best?
So, everybody wants to know, "What's the best air compressor?"
The best air compressor is the one designed to perform the job you need it to do, in the environment where it will operate, and from a brand that has reliable representation and support in your area.
The first questions you should ask yourself are:
What am I going to do with the compressed air?
How many tools or pieces of equipment will I be running at the same time? How much CFM (Cubic Feet per Minute) do I need to produce? What is my minimal operating pressure?Where am I going to install the air compressor?
What kind of environment will it operate in? Will it be indoors or outdoors? Is it a high-dust environment? Will the noise level affect me or my employees? Will I be able to properly duct the heat away from the machine?Does the brand have local representation?
It's not a question of if your air compressor will go down—it's a question of when. When it does, will your technician have to order parts from another state or even another country? Or will they be able to source the parts locally and get you back up and running the same day?
The level of local brand representation is an important factor when choosing an air compressor. A strong local distributor or service provider can significantly reduce downtime, simplify maintenance, and ensure replacement parts are readily available when you need them most.
These are critical questions that many people don't begin asking until after the air compressor has already been purchased and installed—which is putting the cart before the horse.
Single-Stage or Two-Stage Reciprocating or Rotary Screw, which one is right for me?
Reciprocating Air Compressors
A reciprocating air compressor, also known as a piston compressor, is an excellent choice for light to moderate workloads. These compressors are commonly used in home workshops, small businesses, maintenance departments, and construction sites where compressed air is needed periodically rather than continuously.
Single-Stage Air Compressors
Single-stage air compressors are ideal for customers who require more CFM per horsepower but at a lower PSI. A single-stage air compressor produces more CFM per horsepower than a comparable two-stage air compressor. However, single-stage compressors are generally limited to a maximum working pressure of 135 PSI. If your minimum required operating pressure is below 135 PSI, you'll almost always be better served by a single-stage air compressor. It will provide the airflow you need while doing so more efficiently.
Two-Stage Air Compressors
Two-stage air compressors are capable of achieving higher pressures than single-stage air compressors, but they do so at the expense of CFM. If your minimum required operating pressure exceeds 135 PSI, then you will almost always be better served by a two-stage air compressor.
Single-Stage vs. Two-Stage
On a single-stage air compressor, each piston makes one deposit of air into the tank. Each piston compresses the air it draws in to the current tank pressure plus one PSI.
On a two-stage air compressor, the first stage compresses the air to 30 PSI before passing it through an intercooler and into the second stage. The second stage then compresses the air from 30 PSI to the current tank pressure plus approximately one PSI.
The tradeoff is that the same air has to be compressed twice in a two-stage compressor instead of only once in a single-stage compressor. The benefit is the ability to achieve higher pressures. By passing the air through an intercooler between the first and second stages, some of the heat generated during the initial compression is removed.
Rotary Screw Air Compressors
Rotary screw air compressors have become increasingly popular due to their wide range of horsepower options and applications. However, they can be very temperamental depending on their operating environment, maintenance practices, and method of operation.
Rotary screw compressors are commonly operated in one of three modes.
The first, and by far the most common, is Load/No-Load operation. This is similar to drag racing from stoplight to stoplight. The compressor builds to its target pressure, unloads, but continues to run. As air is consumed and system pressure drops, the compressor reloads to 100% capacity, recovers to the target pressure, and repeats the cycle. If the compressor does not receive a signal to reload within approximately ten minutes, it will typically shut down and enter Auto Standby mode. When system demand returns, the compressor automatically restarts and resumes its normal operating cycle.
The second, and least desirable, operating method is Start/Stop. In this mode, the compressor completely shuts off once the target pressure has been reached. When system pressure drops, the compressor starts again and repeats the cycle. Frequent starting and stopping places additional wear on electrical and mechanical components, making this the least desirable operating method in most applications.
My favorite operating method is Modulation.
A modulated inlet valve allows the compressor to maintain full oil pressure throughout operation. By comparison, a Load/No-Load compressor experiences a drop in oil pressure while unloaded, often falling to between 25 and 50 PSI.
With modulation, the compressor simply adjusts the amount of air it produces to match the plant's demand while maintaining full oil pressure. This significantly reduces the wear associated with repeatedly loading and unloading the compressor.
The result is lower maintenance costs over time. Components such as inlet valves, minimum pressure valves, unload/reload solenoids, and other cycling components experience far less stress because they are no longer being opened and closed as aggressively. Everything happens much more gradually, making maintenance more about routine service than replacing worn-out components. This ultimately extends the life of the machine and reduces the overall cost of ownership.
The Cost of Ownership
The cost of owning a rotary screw air compressor can sometimes be prohibitive, although this is a topic many salespeople avoid discussing before the purchase.
Horsepower for horsepower, rotary screw compressors are significantly more expensive to maintain than reciprocating air compressors. In addition to oil changes, rotary screw compressors require replacement air filters, oil filters, oil separators, drive couplings or belts (depending on the design), and scheduled service kits that are typically installed annually.
Reciprocating compressors generally do not require many of these maintenance items, making them less expensive to own over the life of the machine.
We like to say that if a job can be done with a reciprocating air compressor, it probably should be. That said, many customers value the quiet operation of a rotary screw compressor, especially when it's located near work areas or occupied spaces. Like most things, those benefits come at an additional cost.
Reciprocating air compressors cost for the year is less than a $1,000 (oil, filters, belts) while Rotary screw air compressors are in the $1,000’s per year.
Ultimately, the value of those benefits is something each customer must decide for themselves.