Types Of Air Compressors

There are many types of air compressors that come in different sizes. Each application is unique and there is usually a correct compressor for a specific application or requirement. The right compressor, properly maintained and utilized, saves labor, energy costs, and often generates a boost in productivity. With increasing electrical rates and a trend toward smaller maintenance teams, the best choices in air compressors operate with the efficiency and reliability to work better, longer and with less maintenance. Below are several examples of air compressor technologies that are currently used.

types of air compressorsScroll Air Compressors: Uses two spiral elements, one stationary, one orbiting to produce oil-free, contaminant-free compressed air. Scroll compressors are extremely quiet, compact, require very little maintenance and of course are oil-free. Typical applications are Medical, Laboratory, Dental, Food and Beverage, Pharmaceutical and Electronics.

reciprocating air compressorsReciprocating Air Compressors: This technology employs a piston moving forward in a cylinder via a connecting rod and crankshaft. The reciprocating air compressor is extremely versatile. They can be found in the smallest auto repair shops to the largest manufacturing plants. It compresses both air and gases with very little alterations and is the only design capable of compressing air and gas to high pressures.

rotary vane air compressorsRotary Vane Air Compressors: Rotary vane compressors cover a wide performance range and come in dry running and oil lubricated versions. Oil lubricated rotary vanes are the standard pump in numerous industrial applications.

The single rotor design with sliding vanes allows the use of a direct drive arrangement, without the need for belts or pulleys. Its simplistic design and proven reliability make it a viable alternative to other technologies. Its compact size also makes it an ideal choice for customized compressed air and gas applications especially in the transit industry.

rotary screw air compressorsRotary Screw Air Compressors: Rotary screw technology serves the majority of industrial applications today in the 15-500 HP range. It uses male and female rotors that move towards each other while the volume between them and the housing decreases. The screw element is not equipped with any valves and there are no mechanical forces to create any imbalance. It can therefore work at high shaft speed and combine a large flow rate with small exterior dimensions. Typical applications would be Automotive, Food and Beverage, Petrochemical, Aerospace and Electronics manufacturing.

centrifugal air compressorsCentrifugal Air Compressors: Air is compressed by the mechanical action of high-speed, rotating impellers imparting velocity and pressure to the air. Approximately half of the pressure energy is developed in the impeller, with the other half achieved by converting velocity energy to pressure energy as the air speed is reduced in a diffuser and volute. Centrifugal air compressors are best suited for high flow, oil-free applications. Newer designs that use magnetic bearings and high speed motors can offer outstanding efficiency and reliability. Typical applications would be Textiles, Pharmaceuticals, Natural Gas and Chemical industries.

Cost of Ownership: There are many ways to improve compressor efficiency and reduce compressed air cost of ownership, and this doesn’t always involve investing in new equipment. Lewis Systems & Service Co., Inc. can help improve the efficiency and functionality of the entire compressed air system by performing a compressed air audit. We can help you uncover ways to improve your energy efficiency and make significant reductions in operating costs.

A note about service and maintenance: Industry figures estimate that compressed air systems can waste up to 30% of the compressed air through leaks, poor controls or lack of maintenance. In addition, compressor efficiency may degrade with age. Therefore, no matter what type of air compressor your plant has, implementing a compressed air maintenance program is essential to ensure a high level of performance over the years. Lewis Systems & Service Co., Inc. can help you design a program for your in house personnel or we can take care of all your equipment through a custom designed preventative maintenance agreement.

If you’re in need of air compressor services in Virgina or North Carolina, contact our team today at (800) 222-4553!

Medical Gas Industry Frequently Asked Questions

If you are a hospital, lab, outpatient surgery center, dental lab or other healthcare facility in need of medical air and gas solutions in North Carolina or Virginia, there are several questions you should ask when evaluating a service provider. Below are our top 8 FAQs to be aware of during the process.

Can you use Medical Air as Climate Control air? Medical air sources shall be connected to the medical air distribution only and used for air in the application of human respiration and calibration for medical devices for respiratory application. NFPA 99-2012.

Is an Oil-Free screw compressor accepted for Medical Air?  Yes. Rotating element compressors provided with a compression chamber free of oil can be allowed. NFPA 99-2012.

What is the required dew point of Medical Air dryers?  Maximum dew point is below the frost point of 32 degrees F at 50 to 55 PSI and any level of demand. NFPA 99-2012.

What about my Intake for Medical Air, can I put it anywhere? No, it needs to be a clean air source, 25 feet from ventilating systems, vents and other exhausts. It also needs to be a minimum of 20 feet above the ground and 10 feet from any door, window or other opening into the building. NFPA 99-2012.

Can we put the exhaust for the Medical Vacuum anywhere in the basement or in a corridor? No, it has to be outdoors, at least 10ft from any window, door, air intake or other opening into the building. It also needs to be at a different level from other air intakes where prevailing winds or  topography could not divert the exhaust into occupied areas. NFPA 99-2012.

What is WAGD? Waste Anesthetic Gas Disposal. WAGD systems provide the proper evacuation of potentially hazardous waste anesthetic gases during the administration of anesthesia to patients.

Does everyone that installs Medical Air and Vacuum need ASSE 6010 certification? Yes, this is the Professional Standard for Medical Gas installers.

What is the new ASSE 6040 qualification?  This standard applies to persons maintaining, testing and inspecting medical air and vacuum systems. Training and certification can be accomplished through the Healthcare facility by which such persons are employed to work with specific equipment or Credentialing for Professional Qualification Standard for Medical Gas Maintenance Personal. NFPA 99-2012

Visit our site for more on medical gas solutions in Virginia and North Carolina.

Why Should I Change My Filter Element?

The primary reason to replace filter elements every 12 months is to maintain air quality. Filter elements remove contaminants for specific air quality treatment pursuant to the manufacturing industry and the international standards for compressed air quality. Once the 12-month filter life has passed, the required air quality is no longer being maintained.

What about the differential pressure gauge fitted on the filter showing that the needle is in the green range? The differential pressure gauge is only an indicator or premature blockage. It only reflects the measure of the differential pressure not whether the filter should be changed.

However, the differential pressure gauge can alert you to pressure spikes that can rupture the filter element instantly, passing contaminated air through the filter into the compressed air system. If the filter element is damaged, even with a pin-point sized hole, the filter can rupture. Filter elements are constantly bombarded by high-velocity particulate matter as well as acidic condensates – oil, chemical additives, even hot water. 12 months of this type of operation and the filter media is more than ready to be changed.

Avoid getting contaminates in the compressed air system. Change the filter element once every 12 months.

Reducing Costs with Nitrogen Generators

By Robert Glover

Parker Hannifin FNS Division

There are typically two ways to increase profit. First,
you can increase your price. The second is to reduce your cost.

Increasing your price is necessary at times but comes with it some inherent potential of lost business to competition or uncomfortable
conversations with your best customers. Reducing cost is a great option, when it’s available. Your suppliers aren’t eager to reduce their profit so getting price concessions isn’t easy.  That is, unless you could change the rules of the game and produce what others would sell you at a premium.


High pressure cylinder rental can be expensive and difficult to mange.

If a supply of nitrogen is in your cost profile, then you may be able to do just that with the simple addition of a nitrogen generator. A nitrogen generator simply uses a supply of compressed air and, through time tested and simple technology separates out the N2 you need.

Is a nitrogen generator right for you?

It’s common for a gas company to charge their customers per 100 cubic feet of nitrogen delivered. The price for each 100 cubic feet of gas is usually between 35 cents and 60 or 70 cents but can be more than $1.00 or $2.00 depending on the delivery method. The operational cost to produce your
own nitrogen is typically between 12 cents and 18 cents. The majority of this figure is made up of the electrical cost to run the compressed air system so will vary with your price per kw/h.


Having your own Nitrogen Generation System gives you complete control over your purity, meeting your demand and your costs.

It’s this difference (20 cents or more per 100 cubic feet of N2 used) that pays back the capitol and, eventually, provides for the
savings mentioned above. The more consistently you use your nitrogen supply the faster the payback and better the long term savings. Sites using nitrogen 40 hours a week will usually see a 2 to 3 year payback on the capitol while those using it 24/7/365 can see a 6 to 8 month return on their investment. A well-made generator will not require a major overhaul for 10 to 15 years. There are several specifics to each site which will increase or decrease the speed of ROI. These specifics can be quickly reviewed and discussed with a qualified N2 generator specialist.

The next time you have to choose between reduced profit and a price increase, have a look at your nitrogen bill and then contact Lewis Systems. After a free, initial consultation you’ll know if you can reduce your operating cost and keep your profit in house where it belongs.

Robert Glover is the Market Development Manager for Nitrogen Generation Systems at Parker Hannifin FNS Division.  

Compressed Air System Audit – Features & Benefits

With increasing energy costs and a growing demand to be “greener”, the performance and efficiency of your compressed air systems has never been more important.  Potential energy savings not only reduce the environmental impact of your business, they can also improve your bottom line.  This is why you should seriously consider having a professional compressed air system audit.  An audit of this kind should provide a comprehensive evaluation of your plant’s current operating practice and system performance.  Once you have this data in your hand, the potential benefits for performance gains and energy savings are many.

Having a detailed analysis of your compressed air system will help in identifying improvements that can be made.  Restrictions in your piping due to sizing mistakes or old pipes with rust and scale build up can be a cause of pressure loss.  Reviewing your “peak” usage times can help identify posible changes in your production process to help reduce demand.  An audit will help ensure that your plant has the proper sized storage to prevent excessive compressor cycling and ensuring you meet periods of peak demand.  A complete analysis will also allow your control systems to be reviewed.  Poorly designed control systems can result in too many compressors running or running at at higher pressure than you really need.  Both of these have huge impacts on your energy consumption and cost. An audit can tell you what’s wrong with your system controls and overall design.

Most people don’t realize what the actual cost is to operate their system and how it effects their production process and quality. Once you have a compressed air system audit completed, you will see a comprehensive picture of what the real costs are.  Then can you consider evaluating savings or other potential improvements and changes. You will be able to save money and energy as well as reduce your carbon footprint.  If you would like to find out more about our Air Audit Services, please contact us and we’ll be happy to show you how to get the best out of your compressed air system.