About Dual Acting Reciprocating Compressors

When it comes to generating compressed air there are many types of compressors to utilize within a facility.  One of those types is a dual acting reciprocating compressor.  This is a type of positive displacement compressor that takes advantage of a piston style action and actually compresses air on both directions of the stroke.  Below you can see a video from a company that showcases how a dual acting compressor works and gives a good representation of how it is compressing the air on both directions of travel.

Dual_Recip
Click on this image for video

The reciprocating type of air compressor uses a motor that turns a crank which pushes a piston inside a cylinder; like the engine in your car.  In a basic cycle, an intake valve opens to allow the ambient air into the cylinder, the gas gets trapped, and once it is compressed by the piston, the exhaust valve opens to discharge the compressed volume into a tank.  This method of compression happens for both the single and double acting reciprocating compressors.

With a single acting compressor, the air is compressed only on the up-stroke of the piston inside the cylinder.  The double acting compressor compresses the air on both the up-stroke and the down-stroke of the piston, doubling the capacity of a given cylinder size.  This “double” compression cycle is what makes this type of air compressor very efficient.  A single acting compressor will have an operating efficiency between 100 cfm / 23 kW of air while the double acting compressor has an operating efficiency between 100 cfm 15.5 kW .  Therefore, electricity cost is less with a double-acting reciprocating air compressor to make the same amount of compressed air.

These compressors are ruggedly designed to be driven 100% of the time and to essentially be a Clydesdale of compressors.  They are commonly used with applications or systems requiring higher pressures and come in lubricated or non-lubricated models.

If you would like to discuss air compressors or how to efficiently utilize the air that your system is producing so that you aren’t giving your compressor an artificial load that isn’t needed, contact us.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

 

A Brief History of Compressed Air

So where exactly did compressed air come from? How did it become so widely used and where will it go? Both of these are great questions and the answers lie below.

Compressed air can be traced all the way back to the classic bellows that were used to fuel blacksmith fires and forges.  These started as hand pumped bellows, they then scaled up to foot pumped, multiple person pumped, oxen or horse driven and then eventually waterwheel driven.  All of these methods came about due to the demand for more and more compressed air. These bellows did not generate near the amount of air pressure or volume needed for modern day practices yet they worked in the times.  These early bellows pumps would even supply miners with air.

With the evolution of metallurgy and industry these bellows were replaced by wheel driven fans, then steam came about and began generating more industrial sources of power.  The main issue with steam was that it would lose its power over longer runs of pipe due to condensing in the pipes.  Thus the birth of the air compressor was born. One of the largest projects that is noted to first use compressed air was in 1861 during the build of the Mont Cenis Tunnel in Switzerland in which they used compressed air machinery.  From here the constant need and evolution for on-demand compressed air expanded.  The picture below showcases two air compressors from 1896.

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Air Compressors from the old days.

The compressors evolved over time from single stage, to two-stage reciprocating, on to compound, rotary-screw compressors, rotary vane, scroll, turbo, and centrifugal compressors with variable frequency drives.  The efficiency of each evolution has continued to increase.  More output for the same amount of input.  Now we see a two-stage compressor, considered old technology, and wonder how the company can get any work done.

All of the technological advances in compressor technology were driven by the demand sides of the compressed air systems.  Companies needed to power more, go further, get more from less, ultimately increase production.  With this constant increase in demand, the supply of compressed air increased and more efficient products for using compressed air began to evolve so the air was used more efficiently.

Enter EXAIR, we evolved the blowoff to meet the increasing demands of industrial companies to get the same amount of work done with less compressed air. We have continually evolved our product offering since 1983.  It all started with just a few typed pages of part numbers and has evolved to a 208 page catalog offering of Intelligent Compressed Air Products® for industry.  We will also continue to evolve our product designs for continued improvement of compressed air usage.  This is all to better help companies retain their resources.

cat32_500p
EXAIR Catalog 32

If your company uses compressed air and you aren’t sure if it is efficiently being utilized, contact an Application Engineer.  Thanks for joining us for the brief history lesson, we look forward to hearing from you and seeing what the future brings.

Brian Farno
Application Engineer
@EXAIR_BF BrianFarno@EXAIR.com

 

Compressed air (1896) (14594022618).jpg – Wikimedia Commons – Internet Archive Book Images – Link

 

About Rotary Scroll Compressors

The Rotary Scroll compressor is a popular style compressor and is used primarily for air conditioning refrigerant systems.  Recently, since it is very efficient, quiet and reliable it has been adopted by industrial air compressor manufacturer’s to expand their product offering for their smaller, high-efficiency product line.

They operate on the principle of two intermeshing spirals or scrolls with one being stationary while the other rotates or orbits in relation to it.  They are mounted with 180° phase displacement between them which forms air pockets having different volumes.  Air enters through the inlet port located in the rotating/orbiting scroll which fills the chambers and as is moved along and compressed along the scroll surfaces.

scroll compressor finalSome of the key advantages of a Rotary Scroll Compressor are:

  • Pulsation free delivery due to the continuous flow from the suction port to the outlet port.
  • No metal to metal contact thereby eliminating the need for lubrication
  • Low noise levels
  • Fewer moving parts means less maintenance
  • Energy Efficient
  • Air cooled

The largest disadvantage is they are available in a limited range of sizes and the largest SCFM outputs are around 100 SCFM.

This is exactly where EXAIR shines, we offer 15 product lines of highly efficient & quiet point of use compressed air products and accessories to compliment their limited output volume of air.  All EXAIR products are designed to use compressed air efficiently and quietly, many of which reduce the demand on your air compressor which will help control utility costs and possibly delay the need to add additional compressed air capacity.

As an example, EXAIR’s Super Air Knives deliver exceptional efficiency by entraining ambient air at ratios of up to 40:1 and they are able to deliver an even laminar flow of air ranging from a gentle breeze to exceptionally hard-hitting force.

Super Air Knife
EXAIR’s Super Air Knife entrains ambient air at a 40:1 ratio!

EXAIR’s Super Air Amplifiers are able to entrain ambient air at ratio’s up to 25:1.  The model 120024 – 4″ Super Air Amplifier developes output volumes up to 2,190 SCFM while consuming only 29.2 SCFM of compressed air @ 80 PSI which can easily be operated on a 100 SCFM output compressor.

Super Air Amplifier
EXAIR Air Amplifiers use a small amount of compressed air to create a tremendous amount of air flow.

For your blow off needs EXAIR’s Super Air Nozzle lineup has an offering that will fit nearly any need or application you may have.  Nozzles are available in sizes from M4 x 0.5 to  1 1/4 NPT and forces that range from 2 ounces of force up to 23 Lbs at 12″ from the discharge.  We offer sixty two nozzles that could all be operated easily from the limited discharge or a rotary scroll compressor.

nozzlescascadeosha
Family of Nozzles

If you need to reduce your compressed air consumption or you are looking for expert advice on safe, quiet and efficient point of use compressed air products give us a call.  We would enjoy hearing from you!

Steve Harrison
Application Engineer
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