Five Things To Know About Single Acting Reciprocating Compressors

With the development of highly efficient air compressors, there’s still a place for the most basic design: the single acting reciprocating compressor.  When the piston moves out of the cylinder, it draws air in, at atmospheric pressure.  When it moves in to the cylinder, it reduces the volume that air occupies, increasing its pressure.  These machines are durable, effective, relatively inexpensive, and pretty easy to maintain.  Here are a few interesting things to know about them:

1. Popularity. Because of the simplicity of their design, they’re the most common air compressor in the 10HP and under sizes.  You can get them from a number of sources, and they’re not going to set you back as much as some other types.
2. Oil free air (part 1) While the most basic design uses oil to lubricate the piston rings in the compression cylinder, oil-less reciprocating compressors have cylinders with very smooth (and hard) bore surfaces, like nickel or chrome plating. A series of guide rings around the whole circumference of the piston prevent metal-to-metal contact, eliminating the need for liquid lubrication in the compression cylinder.
3. Oil free air (part 2) If oil in your compressed air is a problem, an oil-free (as opposed to oil-less) compressor is another option. While an oil-less compressor doesn’t use lubricant for the piston movement, an oil-free compressor’s moving parts are oil lubricated, but that oil is kept away from the compression cylinder(s) with connecting rod(s) so that the oil is confined to the lower moving parts…the crankshaft and bottom ends of the connecting rods, and away from the pistons & compression cylinders.
4. Foundation. Reciprocating machinery, as the name implies, has parts that move back and forth. The sudden reversal of direction of heavy metal pistons & rods, dozens of times a minute, means that their operation is inherently unbalanced. This out-of-balance condition, though, can be absorbed by properly securing the compressor to a properly prepared foundation.
5. Higher pressures. If your facility’s compressed air usage primarily entails pneumatic tools, cylinders, and blow off devices like air guns, the system header pressure is likely maintained at around 100psig. While a one-stage reciprocating compressor is usually rated for discharge pressures up to 125psig, a second stage can increase that to 175psig. Multi-stage compressors are used for applications that require up to 3,000psig compressed air. Examples of these are scuba breathing air, pneumatic excavators, and my personal favorite: ballast tank blowing air, used to surface a submarine.

4-stage reciprocating compressors charge 3,000psig air tanks that are used to rapidly push water from a submarine’s ballast tanks to create positive buoyancy.  Because keeping your ‘diving-to-surfacing’ ratio at 1:1 is important.

At EXAIR Corporation, helping you get the most out of your compressed air system is important to us.  If you’ve got questions about how to do just that, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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2” Heavy Duty Line Vac Improves Utility Pole Inspection Productivity

Typical Wood Utility Pole

In North America, wood utility poles are pretty much everywhere. And once installed, they have a definite lifespan which can be shortened through rot and insect infestations. For that reason, most utilities will employ an inspection routine to evaluate the strength left within the pole to determine if or when one should be replaced.

The inspection process can vary, but for the purposes of this blog, we will concentrate on the excavation method where a trench of 18” to 24” is dug around the pole base to expose the wood that has been underground. Once the wood has been exposed, the technician can perform a variety of tests to determine the remaining strength left within and recommend repairs or replacement if needed.

The part where EXAIR product comes into play is in the excavation process. Traditionally, the technicians will use a shovel to loosen the dirt around the pole and set it aside for re-packing around the pole once the inspection has completed. Needless to say, the excavation process is somewhat long and tedious as it must be done by hand to keep from damaging the pole and/or utilities that may be nearby. One customer decided to use a 2” Heavy Duty Line Vac to help speed up the excavation process. Instead of pushing on a shovel and continually swinging the dirt around to a tarp about 10 feet away, the technician can make less of an excavation effort by using hand tools to loosen the dirt and the Heavy Duty Line Vac to pull the dirt out of the hole and over to the awaiting tarp. This gives them ample room for inspection processes without overdoing the excavation which is the part that takes the most time anyway.

Companies who deal with utility pole inspections are judged not only on the quality of the inspection but also the quantity of poles that can be inspected in a given time. For this reason, time is of the essence because once you have demonstrated you can successfully inspect X number of poles, then your company is in line to gain more business through increased number of poles to inspect in the next round.

Heavy Duty Line Vacs have been set up to convey more dense materials as well as abrasive materials over longer distances where other forms of conveying simply can’t hold up or simply are too clunky to give just the right effect as is the case in this application.

Are you trying to move dense or abrasive material over distances of 100 feet or more? Give us a shout about your application. Let us show you what the EXAIR Line Vacs can do for you.

Neal Raker, International Sales Manager


Utility pole image (no changes made) courtesy of Christopher Sessums  Creative Commons License