Centrifugal Air Compressors: How Do They Work?

Centrifugal air compressors are one example of dynamic style air compressors. The dynamic type of compressors have a continuous flow of air that has its velocity increased in an impeller that is rotating at a higher speed. The kinetic energy of the air is increased due to the increase in velocity and then becomes transformed into pressure energy through the use of a volute chamber, or a diffuser. The volute chamber is a curved funnel that increases in surface are as it approaches the discharge port. This converts the kinetic energy into pressure by allowing the velocity to reduce while the pressure increases. Approximately 1/2 of the energy is developed in the impeller and the other half is developed in the volute chamber or diffuser.

1 – Basic Centrifugal Air Compressor

The most common centrifugal air comppressor has between two and four stages in order to generate pressures up to 150 psig. A water cooled inter-cooler and separator is placed between each stage in order to remove condensation and cool the air down prior to being passed on to the next stage. These compressors still have advantages and some disadvantages. The list below showcases just a few.

Advantages:

  • Lubricant-free air is generated
  • Complete packages up to 1,500 hp
  • Initial costs decrease with increase in compressor size
  • No special foundations or reinforcements needed

Disadvantages:

  • Specialized maintenance requirements
  • Higher initial investment
  • Unloading/waste of air required to drop system pressures

To determine which type of compressor may be best suited for your facility, we suggest to locate and contact a compressor sales company in your geographic area. When it comes to determining the volume of air required to operate the EXAIR products and even some other point of use compressed air applications, EXAIR’s Application Engineers can help you determine the volume you will need to ensure the compressor is sized appropriately. If you would like to discuss any other point of use application, please contact us.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

1 – Dugan, Tim PE – Basic Centrifugal Air Compressor, Compressed Air Best Practices; retrieved from https://www.airbestpractices.com/technology/air-compressors/centrifugal-air-compressor-controls-and-sizing-basics

Six Sigma and The Compressor Room

Throughout my undergrad courses as well as during my professional career I have encountered Six Sigma or Lean Manufacturing in many facilities.  There is at least one component to the theory that can be implemented into any facility with a compressor room. That component is the practice of the 5 S’s.

The 5 S’s of Lean Manufacturing come from the Japanese terms  listed below with their English translations:

Seiri – Sort (Organize)
Seiton – Set in Order (Orderliness)
Seiso – Shine (Cleanliness)
Seiketsu – 
Standardize
Shitsuke –  Sustain (Discipline)

These 5 points can aid in keeping any air compressor room in a facility efficient, safe, and effectively supplying the company with compressed air. How you may ask.

Sort – Keeping a compressor room as originally laid out and preventing it from being a catch-all for items that have nothing to do with the compressed air system. This can easily happen when it is actually a room that has unused floor space in a small facility. By keeping the area clean and free of unrelated materials, maintenance and troubleshooting can be done quickly. Clear labeling of anything kept in the room is also ideal to make items easily identified.

Set in Order – To deliver the air in a single path/direction as well as keeping equipment in locations where they can be easy to maintain and clearly labeled eases the troubleshooting and understanding of how the system is laid out. Rather than having a spaghetti bowl of piping running all around the room to different components it is wiser to keep a flow that matches the process. From the compressor(s) to the receivers, dryers, filter, and regulators, out to the point of use. This shouldn’t be a tangled web of piping that introduces air to a process which bypasses key components such as the dryer or receivers.

Block diagram of a compressor room layout.

Shine – The compressor room shouldn’t be a dirty grungy area. The compressor pulls the air in from this environment. Any exposed components easily collect airborne debris. By keeping the equipment clean again makes labels easy to read and a clean machine is always easier to perform maintenance and sometimes even troubleshoot. If there are puddles of oil or other liquids on the floor and no surfaces are clean then any leak may not be easily spotted.

Standardize – The layout and processes used within the room should be repeatable. Maintenance tasks should be performed on a schedule, per a process that doesn’t allow for much differentiation on methods and end results. This mitigates errors and is always the desired result when focusing on lean manufacturing. LOWER THAT DELTA!

Sustain – This is sometimes the hardest part of any process. Getting the program up and running, starting with a fresh build is always the easiest.  Everything is fresh, new and you want to keep it shiny. Years later the desire to dust and maintain piping as well as keep receiver tanks and floors clean isn’t always at the top of the desired list.  It should always be a priority because cleanliness also promotes safety and reduces overhead by lowering downturns due to housekeeping related failures.

If you want to discuss how we can help lean out your compressed air usage, maintenance costs, and help to standardize the use of compressed air in your facility, contact an Application Engineer today.

Brian Farno
Application Engineer – Green Belt Certified
BrianFarno@EXAIR.com
@EXAIR_BF

O-Rings, Seals, Gaskets, Maintenace, Filtration – They All Matter

I’ve mentioned it before and I’ll say it again. You can’t teach experience. This was told to me by a mentor at a previous job and of course, younger me thought, “Yeah, yeah I know all I need to know.”  Well, younger me was an idiot and learned many things through experience. Sometimes I am still a slow learner and eventually, I remember those experiences and make decisions based on them. So what does this have to do with o-rings, seals, and gaskets?

I’m in the midst of a light construction project in my house and have reached a stage where some tools that I do not have would come in handy and make the job faster. Younger me would have justified purchasing a new one, experienced me understands a budget and reached out to my network of friends and a good friend said they had the tool I needed. This was a compressed air powered framing nail gun. Straight through nailing, no-problem, toe-nailing, no-problem, this thing won’t break a sweat and your arms will be stronger by the time you are done using it while your thumbs are screaming thank you for not smashing me a hundred times.

The Framing Nail Gun in question

This loan did come with two conditions, one was, he didn’t have any nails to give with it. This was not a problem as I wouldn’t expect a friend to give me free fasteners with a tool loan. The second is the one that concerned me, he said, it does leak a little air but it should still shoot just fine. After working in the compressed air industry for over a decade I have experienced this many times. At that point I knew if you could hear it, chances were it was a bad leak. Upon further inspection, there was a cylinder gasket and rubber spring that were in pieces.

Old Spring Bumper and Main Cylinder Gasket

Gasket pieces and dirty air can result in catastrophic failures.

Nothing that a trip to a local business couldn’t take care of.  A few new parts and discussion with their knowledgeable staff and I had the information needed to rebuild this nail gun to functioning status.

New vs. Old

Oddly enough, my experience and expertise with how the EXAIR products like the No-Drip Air Atomizing Liquid Spray Nozzles operate and how to rebuild them, provided a good foundation about how this tool worked. This repair ended up being very similar to the rebuild on a No-Drip Spray Nozzle.

This story is two-fold, filtration could have prevented a lot of the damage to this gun. This gun uses a good amount of air volume at an expedient pace so keeping it clean and clear of debris helps extend the lifetime of internal parts.  See my video on what happens without filtration below.

The second part is that maintaining and understanding processes to clean/rebuild are crucial to sustainable function of a machine. The cleaning process for this gun was fairly straightforward and using the correct lubricant for reassembly was another critical role. This culminated in a framing nail gun that can now be used to further my project and will more than likely live another decade before needing a rebuild again. That is if filtration and proper lubrication are followed.

Had I not obtained experiences throughout my career that helped me to understand how this tool functioned, the worth of a reliable network of vendors, and the necessity to complete tasks that take me out of my comfort zone I wouldn’t be in the place I am today. Because I have the experience and the network to ask for help it enables me to keep machines running that could have cost valuable production hours had this been a production environment.

EXAIR stocks rebuild kits, gaskets, shims, and parts for all of our product lines which may require a repair. For products which need to be cleaned in order to return back to new performance, we have the instructions or can do it for you here. From time to time they may need a repair or refurb in order to keep functioning at peak performance. If you want to build your trusted network or learn more about how to rebuild or clean EXAIR products, contact us.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

Built to Last

The past few months many of our lives have been altered in some fashion due to COVID-19. Personally, my three daughters began staying home full time and attending school through distance learning.  I myself switched to working some alternate shifts which EXAIR changed to in order to optimize our availability to our customer base as well as protect our team members effectively. I know many in manufacturing that have been furloughed. Even worse, some have been forced to work in unsafe conditions.

All of this has made me thankful I am part of a team that cares about our employees first, and then we all work towards ensuring our customers are taken care of. Our new shift structure has also given me time to reflect on many aspects of my life.

When I was younger, like many kids, I always wanted something I received to be new. I didn’t want an older hand me down bicycle, I wanted new.  Little did I know I would reach a point in life where I prefer things to be a little older, a little more seasoned, even broken-in if you will.  The days are here where disposable is what everyone expects whenever they purchase anything. Repairable is often a thing of the past and or requires specialty tools and or software.  I’ve been recently working on lots of small engines from friends and family members yard equipment and recreational vehicles.

I’ve worked on a 1970’s era Stihl chainsaw that the only safety is the weight of the saw and an on/off toggle switch, up to an imported 4 wheeler that instead of buying a single piece or carburetor kit, most people throw them away and buy new.  Something about the older equipment makes me think I was born in the wrong era. The time of working hard for what you make and taking pride in products lasting a lifetime is often gone from consumer-grade products.  When carburetors are riveted together to make them faster and cheaper to assemble, but also not easily repairable, the chance of someone repairing it 40 years from now diminishes.

It could be that I am closer to 40 than I am to 30, however, I find that being able to source parts direct from a manufacturer as well as being able to get support direct from the manufacturer is something I desire. This could also be because this is how we do business at EXAIR. Our compressed air products all carry a 5 year Built to Last Warranty, we service them, sell replacement parts for them and take pride in their ability to last.

There are few items that I am okay with going a cheap route on, spare screwdrivers, you know the ones you use as pry bars and oil filter punches, and anything I know I am only going to use once and I am okay if it breaks as long as it is worth a laugh.  When I went to repair a weed eater for a neighbor I found the engine casing was plastic, there was barely anything to the motor and the lack of maintenance on his part as well as the ethanol in the fuel with lack of stabilizer had gummed up the entire fuel system.

This was a disposable weed eater and he admitted it wasn’t cheap but he also knew it wasn’t a big brand name. Experiencing this, made me laugh.  I went to my older weed eater that has seen many days. It was bought used at an auction. I gladly started it up for him and offered to loan it out whenever he needed. That weed eater was built to withstand its use. Parts are readily available and it is so popular there are many of the parts reproduced through third party factories pretending to be the company.

Next up on my project list may be the biggest project yet, a tiller that is far older than I am. This again has been brought on by the want for a healthy garden and the ability to also help neighbors and friends when they are ready for their gardens.  Rather than looking new, I started at the old, something I knew was built for hard work, and was ready for the task.  I doubt there is a single piece of aluminum on this thing, it has probably seen more sweat throughout its years than I have in my lifetime.  First, the research though.  Parts, service manuals, and then the negotiation of the purchase. (Both with my wife, and the seller. Separately of course.)

Here at EXAIR, we can get nostalgic over some of our products and processes as well. At the same time, we continuously flex and work with the matters a hand. If you have an old product of ours that you think may not be worthy of use, give us a call. With a few pictures and some information, our team of Application Engineers should be able to help determine if it is in good working order or not.  If we cannot determine from pictures, we can always receive the unit in and inspect it for you. In the event it is not in working condition, we more often than not can refurbish the unit and have you back up and running within a few days.  Our Super Air Knives are a product that often gets overlooked when they get covered in debris from a process. We can inspect them, clean them, and often restore them to flowing like a brand new knife.

Brian Farno
Aging Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF