Intelligent Compressed Air: Single Acting Reciprocating Air Compressors

Of all the types of air compressors on the market, you can’t beat the single acting reciprocating air compressor for simplicity:

Piston goes down: air is pulled in. Piston goes up: air is pushed out.

This simplicity is key to a couple of major advantages:

  • Price: they can cost 20-40% less than a similar rated (but more efficient) rotary screw model, up to about 5HP sizes.  This makes them great choices for home hobbyists and small industrial or commercial settings.
  • High pressure: It’s common to see reciprocating compressors that are capable of generating up to 3,000 psig.  Because the power is transmitted in the same direction as the fluid flow, they can handle the mechanical stresses necessary for this much better than other types of air compressors, which may need special modifications for that kind of performance.
  • Durability: out of necessity, their construction is very robust and rugged.  A good regimen of preventive maintenance will keep them running for a good, long time.  Speaking of which…
  • Maintenance (preventive): if you change your car’s oil and brake pads yourself, you have most of the know-how – and tools – to perform regular upkeep on a reciprocating air compressor.  There’s really not that much to them:

    The internals of a single acting reciprocating compressor.

Those advantages are buffered, though, by certain drawbacks:

  • Efficiency, part 1: The real work (compressing the air) only happens on the upstroke.  They’re less efficient than their dual acting counterparts, which compress on the downstroke too.
  • Efficiency, part 2: As size increases, efficiency decreases.  As stated above, smaller sizes usually cost appreciably less than more efficient (rotary screw, vane, centrifugal, etc.) types, but as you approach 25HP or higher, the cost difference just isn’t there, and the benefits of those other types start to weigh heavier in the decision.
  •  Maintenance (corrective):  Whereas they’re easy to maintain, if/when something does break, the parts (robust and rugged as they are) can get pretty pricey.
  • Noise: No way around it; these things are LOUD.  Most of the time, you’ll find them in a remote area of the facility, and/or in their own (usually sound-insulated) room.
  • High temperature:  When air is compressed, the temperature rises due to all the friction of those molecules getting shoved together…that’s going to happen with any air compressor.  All the metal moving parts in constant contact with each other, in a reciprocating model, add even more heat.
  • Oil in the air: If you’re moving a piston back & forth in a cylinder, you have to keep it lubed properly, which means you have oil adjacent to the air chamber.  Which means, no matter how well it’s built, you’re likely going to have oil IN the air chamber.

All that said, the benefits certainly do sell a good number of these compressors, quite often into situations where it just wouldn’t make sense to use any other type.  If you’re in the market for an air compressor,  you’ll want to find a local reputable air compressor dealer, and discuss your needs with them.  If those needs entail the use of engineered compressed air products, though, please feel free to give me a call to discuss.  We can make sure you’re going to ask your compressor folks the right questions.

Russ Bowman
Application Engineer
EXAIR Corporation
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Sound Power Vs Sound Pressure

sound-level-comparison
EXAIR Intelligent Compressed Air Product dBA ratings as compared to other sounds

When trying to explain or state a number associated with how loud a sound or noise is it can be somewhat confusing or at the very least, ambiguous.  This blog will help to make it clear and easy to understand the difference between Sound Power and Sound Pressure.

Sound Power is defined as the speed at which sound energy is radiated or transmitted for a given period of time.  The SI unit of sound power is the watt. It is the power of the sound force on a surface of the medium of propagation of the sound wave.

Sound Pressure is the sound we hear and is defined as the atmospheric pressure disturbance that can vary by the conditions that the sound waves encounter such as furnishings in a room or if outdoors trees, buildings, etc.  The unit of measurement for Sound Pressure is the decibel and its abbreviation is the dB.

I know, the difference is still clear as mud!  Lets consider a simple analogy using a light bulb.  A light bulb uses electricity to make light so the power required (stated in Watts) to light the bulb would be the “Sound Power” and the light generated or more specific the brightness is the “Sound Pressure”.  Sound just as with the light emitting from the bulb diminishes as the distance increases from the source.  Skipping the math to do this, it works out that the sound decreases by 6 dB as the distance from the sound source is doubled.  A decrease of 3dB is half as loud (Sound Pressure) as the original source.  As an example sound measured at 90 dB @ 36″ from the source would be 87dB at 54″ from the sound source or 84dB at 72″.

We at EXAIR specialize in making quiet and efficient point of use compressed air products, in fact most of our products either meet or exceed OSHA noise standards seen below.

OSHA Noise Level

EXAIR also offers the model 9104 Digital Sound Level Meter.  It is an easy to use instrument for measuring and monitoring the sound level pressures in and around equipment and other manufacturing processes.

If you have questions about the Digital Sound Level Meter, or would like to talk about any of the quiet EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR or any Application Engineer.

Steve Harrison
Application Engineer

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Proper Air Supply Line Size Equals Proper Performance

Pipe_460top
Properly sized piping will allow your compressed air operated equipment to operate efficiently!

On any given day myself and my Application Engineering Brethren here at EXAIR have discussions with customers on air starvation of any given EXAIR Product.  The calls generally start off the same, “The Line Vac is not performing like it should”.  We at EXAIR absolutely want to help you get the most out of our products and we certainly want them to perform to your expectation.  However they must be supplied with clean/dry compressed air at sufficient pressure and volume.

Just the other day I was discussing a performance issue with a customer on a 1″ Line Vac.  The customer thought he needed a larger Line Vac.  I asked the questions regarding the diameter of his Supply Line and if he was using Quick Connect or Push Lock connectors.  He was attempting to feed this Line Vac with 1/4″ Poly Tubing through a elbow Push to Loc fitting.

This 1″ Line Vac was being severely starved for air and therefore not performing as expected.  The 1″ Line Vac require’s 14.7 SCFM @ 80PSI to reach the rated performance of 42″ of water column.

Below is a table for Pipe/Hose sizing from the Line Vac installation manual that you can use as a reference guide.  It is recommended that if using hose for the supply air to go up to the next size over the pipe recommendation.

Chart2

Don’t forget that quick connects and Push Lock fittings are not recommended and could restrict the air flow which will have a negative impact on performance.

If you would like to discuss Line Vacs or any EXAIR product,  I would enjoy hearing from you…give me a call.

Steve Harrison
Application Engineer
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Compressed Air Uses In Industry

Air Compressor

There are so many uses for compressed air in industry that it would be difficult to list every one of them as the list would be exhaustive.  Some of the uses are the tools used in production lines, assembly & robotic cells, painting, chemical processing, hospitals, construction, woodworking and aerospace.

It is considered as important as water, electricity, petroleum based fuels and often referred to as the fourth utility in industry. The great advantage of compressed air is the high ratio of power to weight or power to volume. In comparison to an electric motor compressed air powered equipment is smoother.  Also compressed air powered equipment generally requires less maintenance, is more reliable and economical than electric motor powered tools.  In addition they are considered on the whole as safer than electric powered devices.

Even amusement parks have used compressed air in some capacity in the operation of thrill rides like roller coasters or to enhance the “wow factor” of certain attractions. Compressed air can be found in your dentist’s office where it is used to operate drills and other equipment. You will find compressed air in the tires on your car, motorcycle and bicycles. Essentially, if you think about it, compressed air is being used nearly everywhere.

Here at EXAIR, we manufacture Intelligent Compressed Air Products to help improve the efficiency in a wide variety of industrial operations. Whether you are looking to coat a surface with an atomized mist of liquid, conserve compressed air use and energy, cool an electrical enclosure, convey parts or bulk material from one location to another or clean a conveyor belt or web, chances are we have a product that will fit your specific need.

Atomizing nozzle
Atomizing Nozzles Can Apply Even Coatings
Super Air Amplifier
Air Amplifiers pull in a large volume of ambient air to increase air flow volume and are great for cooling applications!
Heavy Duty Threaded Line Vac
For conveying heavy or abrasive products the Heavy Duty Threaded Line Vacs have male NPT Threads to make permanent and rigid installation into a piping system a breeze.

If you would like to discuss quiet, efficient compressed air products, I would enjoy hearing from you…give me a call.

Steve Harrison
Application Engineer
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