Piston compressors are still the most common type found in the automotive service industry. However, compressor technology is changing and many shop owners are finding out what large facilities and industrial manufacturers have known for years: There are significant benefits to using rotary screw technology.
These types of compressors are more energy efficient and provide an extremely reliable supply of clean, dry compressed air.
When evaluating a facility’s compressed air system, consider duty cycle and performance, energy efficiency and maintenance requirements.
Piston compressors are relatively inexpensive to buy and routine maintenance is minimal, but they are loud, vibrate a lot, produce less air per kW and the air is usually wetter and oilier. Further, the pumps should be rebuilt periodically to replace rings and valves to maintain performance and reduce oil consumption.
They are not 100 percent duty cycle machines and run hotter as efficiency decreases and operating time increases.
Rotary compressors are more expensive to buy and maintain, but are generally built to operate many times longer without major repair. They run much cooler, have better filtration and pass less oil.
Rotary compressors generally make more air per kW. This, plus their 100 percent duty cycle, means you can often use a smaller hp rotary machine in place of a piston type.
But if you don’t need clean, dry air and only need the compressor occasionally, a piston may be more cost effective long term.
Finally, calculate the cost of downtime in your shop and consider whether it makes sense to have two smaller compressors instead of one large one. In addition to providing back up, running two small compressors will probably lower your energy bill.