About Rotary Screw Air Compressors

What is an air compressor? In simple terms it is a machine that increases fluid pressure, it works by changing the volume of air and storing it in a storage tank. Many industries use compressors to increase production and thus has led to the development of many new industries. There are a couple types of air compressors but today I will focus on the Rotary Compressor.

The Rotary Screw Compressor is a very common type of air compressor. This compressor uses dual rotors with meshing lobes that trap air while rotating. The rotation continues to push air toward a discharge port while decreasing the space the air take sup, thus increasing pressure. The rotary compressor has a simple structure with few components and has some clear advantages over other compressors:

  • Longevity
  • When operating, they are quiet
  • Low vibration
  • Continuous operation, or they can match demand

Some disadvantages include:

  • Skilled maintenance required compared to other compressors.
  • They are more expensive than other compressors

There are two types of rotary air compressors. They are oil-injected and oil-free rotary air compressors. Oil-injected rotary screw compressors as the name suggests has oil injected in the compressor element during the air compression. An insignificant amount of oil will escape into the compressed air system also known as “oil carryover”. The use of EXAIRs oil removing filters and filter separators will help remove the oil, moisture and other particulates from the compressed air lines resulting in clean compressed air.

Oil-free rotary screw compressors are similar to the oil-injected compressor but without the use of oil. The oil-free compressors use a two stage system with a cooling process between stages as the compressed air will become extremely hot if not for a cooling process between stages of compression. The oil-free compressors are commonly used in food and medical industries.

EXAIR is here to help with your “Intelligent Compressed Air Products” so please contact us with your compressed air tooling needs.

Eric Kuhnash
Application Engineer
E-mail: EricKuhnash@EXAIR.com
Twitter: @EXAIR_EK

File:IngersollRand R-series-R110.jpg image is licensed under the Creative Commons Attribution 3.0 License.

EXAIR Calculators for ROI


At EXAIR, we want to ensure our customers have access to as much technical data and information as possible. When visiting www.EXAIR.com be sure to review our “Resources” tab where you will find; 3D models and CAD Library, Case Studies, FAQ’s, Applications, PDF Library, Calculator Library, Slide Presentations, Videos, Efficiency Lab, Webinars, Air Data, Cabinet Cooler Sizing Guide and Application Assistance. Let us take a look at the “Calculator Library”.

EXAIR wants you to be fully aware of the benefits of our products so inside the “Calculator Library” we have calculators that help you understand the savings you will obtain from purchasing and using EXAIR products. Using the calculator resources will give you the confidence of knowing your Return on Investment and help to justify your time and purchase of our products – just in case our word is not enough.

The “Cost Savings Calculator” will help you, just as the title suggests, to calculate the savings you gain from using an EXAIR product compared to your current product. Simply put in the data and you will easily see the savings that will help you justify any purchase. The savings can be calculated in USD or Euro.

The “EFC Calculator or Electronic Flow Control is an EXAIR Optimization product that will turn your compressed air off when not needed. This calculator can be used to determine the air and USD (or Euro) savings potential for your application when an EFC is installed.

These calculators and other resources located on www.EXAIR.com will help answer your questions. But if needed, please contact us directly and ask for Application Engineering.

Eric Kuhnash
Application Engineer
E-mail: EricKuhnash@exair.com
Twitter: Twitter: @EXAIR_EK

The cost of compressed air leaks – the need to find and fix them

As margins get tighter and cost of manufacturing climbs, industries are looking for ways to be more economical.  A big focus today is in the compressed air systems.  Compressed air is considered to be the “fourth” utility behind gas, water, and electricity.  Air compressors are necessary to run pneumatic systems, but it is the least efficient of the utilities.  For every $1.00 that is put into making compressed air, you only get roughly 5¢ of work from it.  So, it is very important to use this utility as resourceful as possible. 

One of the biggest problems affecting compressed air systems are leaks.  That quiet little hissing sound from the pipe lines is costing your company much money.  For the amount of electricity required to produce compressed air, a study was conducted by a university to determine the percentage of air leaks in a typical manufacturing plant.  In a poorly maintained system, they found that 30% of the compressor capacity is lost through air leaks on average.  Majority of companies do not have a leak prevention program; so, they will fall into the “poorly maintained” category.  To put a dollar value on it, a leak that you cannot physically hear can cost you as much as $130/year.  That is just for one inaudible leak in hundreds of feet of compressed air lines.  For larger leaks, you can tell by the chart below the amount of money that can be wasted by the size of the hole.  Unlike a hydraulic system, compressed air is clean; so, leaks will not be visible at the source.  You have to find them by some other means. 

**Note 1

Most leaks occur where you have threaded fittings, connections, hoses, and pneumatic components like valves, regulators, and drains.  The Optimization products that EXAIR offers are designed to help optimize your compressed air system, and the most effective way is to find and stop leaks.  The Ultrasonic Leak Detectors can find inaudible air leaks, and the Digital Flowmeters can check your system to find leakage rates.  With both products included in a leak prevention program, you will be able to keep your compressed air system running optimally and reduce the cost caused by wasting compressed air. 

Ultrasonic Leak Detector

EXAIR Ultrasonic Leak Detector:

When a leak occurs, it emits an ultrasonic noise caused by turbulence.  These ultrasonic noises can be at a frequency above that which is audible for human hearing.  The EXAIR Ultrasonic Leak Detector can pick up these frequencies and make the leaks audible.  With three sensitivity ranges and LED display, you can find very minute leaks.  It comes with two attachments; the parabola to find leaks up to 20 feet away, and the tube attachment to define the exact location in the pipe line.  Once you find a leak, it can be marked for fixing.

EXAIR’s Digital Flowmeter w/ USB Data Logger

EXAIR Digital Flowmeter:

With the Digital Flowmeters, you can continuously watch for waste.  Air leaks can occur at any time within any section of your pneumatic area.  You can do systematic checks by isolating sections with the Digital Flowmeter and watching for a flow reading.  Another way to monitor your system would be to compare the results over time.  With the Digital Flowmeters, we have a couple of options for recording the air flow data.  We have the USB Datalogger for setting certain time increments to record the air flows.  Once the information is recorded, you can connect the USB to your computer, and with the downloadable software, you can view the information and export it into an Excel spread sheet.  We also offer a wireless capability option with the Digital Flowmeters.  You can have multiple flow meters that can communicate with your computers to continuously log and record the flow information.  Once the flow information starts trending upward for the same process, then you can use the Ultrasonic Leak Detector to find the leak.  It can also give you a preventive measure if a pneumatic system is starting to fail.

Compressed air leaks will rob you in performance, compressor life, and electrical cost.  It is important to have a leak prevention program to check for leaks periodically as they can happen at any time.  The EXAIR Ultrasonic Leak Detector and the Digital Flowmeters will help you accomplish this and optimize your compressed air system.  If you need more information, you can contact an Application Engineer at EXAIR.  Once you find and fix all your leaks, you can then focus on improving the efficiency of your blow-off devices with EXAIR products.  It will save yourself even more money

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

**Note 1: Chart was published by Compressed Air Challenge in April 1998 – Rev. 0

Proper Labeling of Piping Systems Increases Safety

Industrial facilities can have a multitude of piping and utilities within them. Some of the piping can all look similar, especially if it is not labeled. water, sprinkler lines, compressed air, even steam, and refrigeration lines are just a few of those that can easily be seen within a number of manufacturing facilities. Proper labeling of these helps to ensure plant safety and can also lead to higher efficiencies within the system.

Properly labeled compressed air piping.

So how does labeling lead to safety? Well, in more than one occurrence I have been inside of facilities where piping that was not intended for compressed air, such as PVC was used for it. When the incorrect piping gets used it can become easily confused and if the contractor that is installing new equipment doesn’t do their homework then it can lead to catastrophic errors. For instance, piping can rupture, or even worse, you could easily pipe the incorrect utility into a piece of equipment. Imagine seeing PVC pipe, which is used for water, and hooking it to a rinse application only to find someone improperly used the piping for industrial compressed air. Or vise versa, an unlabeled pipe thought to be compressed air is actually city water and the next thing happening is water raining down on a packaging blowoff.

Cold Water Piping Labeled properly.

This all can and should be easily prevented by properly labeling any and all piping systems thoroughly throughout the facility. This not only names the utility but generally shows the flow direction as well which an help determine where the source is coming from as well. When performing the first step in the 6 Steps To Compressed Air Optimization knowing the direction of flow is critical when installing a Digital Flowmeter in order to assess system efficiency for compressed air.

The proper labeling and utilizing proper piping within industrial environments can easily prevent accidents and ensure ease of troubleshooting or new installations because the piping is already labeled. If you would like to discuss more on what types of piping are acceptable to use with compressed air, feel free to contact an Application Engineer.

Brian Farno
Application Engineer