Selecting the right unit for a job has become a more complicated venture due to new technology and engine options the help to improve both the reliability and durability of air compressors. Traditionally, the two most important variables affecting air compressor selection have been volume and pressure. While these factors continue to remain the starting point for air compressor selection, there are many additional considerations which can result in identifying the right air compressor. Not to lessen their importance, the consideration for volume and pressure continue to help in narrowing the choices.   

 "Gasoline-engine air compressors top out at a volume of 185 cfm and there are still no units available with gasoline engines for higher volumes," says Jeremy Bailey, Air Products Manager- Americas, Doosan Portable Power. "Looking at electric-driven air compressors, they are only available in the 400 to 900 cfm range. In Europe, we are seeing some popularity growing for 90 to 185 cfm electric-driven air compressors."

185 cfm and Lower

For powering pneumatic tools, abrasive blasting and other applications that fall within the 185 cfm and lower range, the air compressor fuel choices are either gasoline or diesel. If the choice between these two options is based on price alone, the gasoline-engine air compressor is the best choice, especially when compared to Tier 4 Final models.

"A gasoline-engine air compressor will perform as well as a diesel unit and last nearly as a result of advances in electronic fuel injection technology; and it is also offered at a lower price point," says Bailey. "Since all air compressor manufacturers are Tier 4 Final compliant, the gasoline air compressor option is the least expensive."

In addition to comparable performance and the lower acquisition price, gasoline air compressors will outperform diesel air compressors for some applications and environments. Because gas engines are spark ignited, they are easier to start in cold conditions than diesel engines. "Contractors have been recognizing the gasoline units' cold starting capabilities and selecting gas air compressors because of the fact that they not only start easier but also warm up faster," says Bailey. "That adds to productivity since there's no waiting for a diesel engine to warm up nor any reliance on a block heater."

Despite the advantages offered by gasoline-powered air compressors, diesel units may still be the best option because of convenience and the jobsite fleet since air compressors are usually part of a larger fleet of machines. It's a common practice to have a fuel truck refill every machine on a jobsite following a set schedule. It makes sense to have a common fuel source throughout the fleet not only from a logistics standpoint, but also the budget.

"It's easier to have a diesel air compressor on the job if you're filling up other machines," says Bailey.

400 to 900 cfm  

In general construction, pipeline testing, and other applications which require 400 to 900 cfm, the two air compressor options are diesel and electric units. Electric-driven air compressors offer a lower acquisition price and reduced operating expense since electricity costs less than diesel fuel. But there is a need for access to electricity to operate electric air compressors either with a mobile generator or hard-wired grid electricity.

"When comparing diesel to electric, an electric air compressor is a much lower cost per cfm alternative," says Bailey. "And, when the jobsite is more remote, diesel air compressors may be the best choice because of the accessibility to diesel fuel."

An electric-driven air compressor is dependent on a power source which also requires the unit to remain relatively stationary and within a close proximity to a power source which can be difficult on a busy jobsite. When there's ready access to electrical power and limited transport needs for the unit, an electric-driven air compressor offers several advantages, including a wide range of cfm and psi, lower maintenance costs and fewer emissions regulations.

Some electric air compressors offer the benefit of variable pressure and flow. For example, the Doosan Portable Power VP900e Electric-Driven Air Compressor has the capability to set the pressure at any level from 90 to 150 psi; this variable pressure capability is an industry first for portable air compressors. The VP900e also automatically adjusts the flow to match the needs of the job, operating between 400 and 900 cfm with no wasted energy.

Because Tier 4 Final air compressors may require additional fluids, cost and time associated with regeneration, an electric air compressor may be the best choice due to limited maintenance needs.

An electric air compressor offers 100 percent emissions-free operation and is not subject to the EPA emissions regulations or Transport Canada fuel tank regulations. There is also no need to purchase, store and transport potentially hazardous diesel fuel, which makes electric-driven air compressors more economical and safe

"In bridge work applications where existing power is readily available, the VP900e electric air compressor has been popular," says Bailey. "An electric air compressor plugs into existing power and operates around the clock without the need to refuel daily which is necessary for a diesel air compressor."

Air compressor begins with looking at the job and application volume and pressure requirements. That information combined with consideration for diesel, gas or electric, can result in an air compressor that best fits jobsite operation needs while providing the greatest advantages with the fewest limitations.