How a Centrifugal Compressor Works

Continuing our series on different types of air compressors, today’s blog will feature the centrifugal compressor.  The centrifugal compressor is classified as a dynamic compressor.  Dynamic compressors are designed to work with  a continuous flow of air that has its velocity increased by an impeller rotating at a very high speed.

The centrifugal compressor works by transforming the kinetic energy and velocity into pressure energy in the diffuser.  The air passes through the inlet guide vanes being drawn into the center of a rotating Impeller with radial blades and is then pushed outward from the center by centrifugal force. This radial movement of air results in a pressure rise and the generation of kinetic energy.  The kinetic energy is also converted into pressure by passing through the diffuser.

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Sample Centrifugal Compressor

Multiple stages are required to raise the pressure to a sufficient level for typical industrial plant requirements.  Each stage takes up a part of the overall pressure rise of the compressor unit.  Depending on the pressure required for the application, a number of stages can be arranged in a series to achieve a higher pressure.

The most common centrifugal air compressor has two to four stages to generate pressures of 100 to 150 PSIG and incorporates a water cooled inter-cooler and separator between each stage to remove condensation and cool the air prior to entering the next stage.

Centrifugal compressors are the near middle of the road regarding efficiency, their typical operating cost is 16 to 20 kW/100 CFM.  The most efficient compressor type is the double-acting reciprocating and costs 15 to 16 kW/100 SCFM and the least is the Sliding Vane which costs 21 to 23 kW/100 SCFM.

Advantages of the centrifugal air compressor:

  • Up to 1500 HP systems are available
  • Price per HP drops as system size increases
  • Supplies lubricant-free air
  • Special installation pads are not required for installation

Disadvantages of the centrifugal air compressor

  • Costs more Initially
  • Requires specialized maintenance
  • Due to high rotational speeds (can exceed 50,000 RPM) precision high speed bearings and vibration monitoring are required

EXAIR recommends contacting a reputable air compressor dealer in your area to discuss your volume and pressure requirements to determine the best size & type air compressor for your needs.

Regardless of the type of air compressor you have, EXAIR’s Intelligent Compressed Air Products® can minimize your compressed air consumption, potentially reducing the size of compressor needed, reduce noise and still deliver powerful results!   If you would like to discuss highly efficient and quiet point of use compressed air products or any EXAIR product, we would enjoy hearing from you. 

Steve Harrison
Application Engineer
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Image Courtesy of  the Compressed Air Challenge

Static Elimination for Tight Spaces or Areas Sensitive to Airflow

If you’re having problems with static build up on small and/or lightweight materials where even the smallest amount of airflow can disturb the product, EXAIR has the perfect solution, the EXAIR Gen4 Ionizing Point.  The Gen4 Ionizing Point is a single point ionizer that lends itself naturally to winding, rewinding, slitting or a myriad of other applications.  It can even be mounted through the wall of a duct to neutralize static charges in an existing air or conveyance duct.

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EXAIR’s Ion Point In Action

The Gen4 Ionizing Point is very powerful and robust solution that can dissipate 5,000 volts in .24 seconds from 2″ (51mm) away!  The Gen4 Ionizing Point features an electromagnetically shielded high-voltage cable that is armored to protect against abrasion and cuts and its integrated ground design does not require a separate ground connection.  For even more convenience the Gen4 Ionizing Point is replaceable if the point should ever become dull or bent.

Ionizing Point Performance

Its smaller footprint naturally lends itself to installation into the limited space normally associated with smaller applications.  The stainless steel, and replaceable, emitter point is mounted in a saddle that is 1.77″ (45mm) long by 1″ (26mm) wide and includes two .20″ (5mm) mounting holes that are 1.44″ (37mm) apart for easy mounting.

Gen4 Ion Point 3

Gen4 Ionizing Points are supplied power by either the model 7960 power supply which can operate up to two ionizing products or the 7961 that can operate up to four ionizing products.  Both models feature selectable voltage to run on either 115 VAC or 230 VAC.

The Gen4 Ionizing Point is the perfect solution for spot static elimination without air assistance.  Most importantly both the EXAIR Gen4 Ionizing Point and Gen4 power supplies are UL component recognized to US and Canadian safety standards, and are CE and RoHS compliant.

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All EXAIR Gen4 Static Eliminators use one of two Power Supplies – your choice of the 2-port Model 7960, or the 4-port Model 7961.

When you are looking for static relief application assistance or expert advice on safe, quiet and efficient point of use compressed air products give us a call.   We would enjoy hearing from you!

Steve Harrison
Application Engineer
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Compressed Air Flow Meter With Wireless Capability Makes Monitoring Demand Easy

Would you like the ability to monitor your plants compressed air usage from one convenient location?  If the answer is yes, EXAIR has just the solution to fit your needs, EXAIR’s Digital Flow Meter with Wireless Capability.

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Wireless capability is an option for EXAIR’s Digital Flowmeter’s.  It is the efficient way to monitor your compressed air consumption wirelessly utilizing the ZigBee® mesh network.  This is accomplished by a module located within the meter that transmits data to an ethernet connected gateway.  Each meter has a range up to 100 feet (30 meters), however the ZigBee mesh network protocol is very versatile as it allows data to also be transmitted from meter to meter, effectively extending the distance over which the system can operate.  So large facilities with great distances to cover are not a problem.

The Digital Flowmeter with Wireless Capability is offered in a kit with a wireless output flow meter, wireless to ethernet gateway, drill guide, power supplies for each component, and ethernet cable for gateway connectivity.  These kits are best suited for new installations.  They are also available without a gateway if you are simply adding an additional meter to a pre-existing Gateway in your plant.  EXAIR simplifies this process by configuring each gateway to communicate with the flowmeter to provide the necessary communication for monitoring your system.  Models from 1/2″ to 4″  iron pipe are in stock. 5″, 6″ iron pipe,  copper pipe ranging from 3/4″ to 4″ diameter and aluminum pipe from 25mm to 101mm diameter are available with short lead time as a special product offering.  Each digital flowmeter is calibrated for the pipe size to which it is mounted and the large digital display shows air use in either SCFM or Cubic Meters per Hour.

Digital Flow Meter Kit
Digital Flowmeter w/ Wireless Capability, Gateway, and Drill Guide Kit

Setting up the EXAIR Digital Flow Meter with Wireless Capability is super easy.  After the meter is installed download the graphing software from our website and install on your computer.  There is also a video tutorial posted in the previous blog from Tyler Daniel, Video Blog: EXAIR’s New Wireless Digital Flowmeter Installation.

The Digital Flowmeter with Wireless Capability is designed for permanent or temporary mounting to the pipe.  It requires the user to drill two small holes through the pipe using the optional drill guide which includes the drill bit and locating fixture.  The two flow sensing probes of the flowmeter are inserted into these holes.  The unit seals to the pipe once the clamps are tightened.  No cutting, welding, adjustments or calibration are needed, ever!  If the unit needs to be removed, blocking rings are available for the 1/2″ to 4″  iron pipe sizes from stock with other sizes available on short lead time as special orders.

If you have questions on Digital Flowmeter’s, Digital Flowmeter’s with Wireless Capability or need expert advice on safe, quiet and efficient point of use compressed air products give us a call.   We would enjoy hearing from you!

Steve Harrison
Application Engineer
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About Rotary Scroll Compressors

The Rotary Scroll compressor is a popular style compressor and is used primarily for air conditioning refrigerant systems.  Recently, since it is very efficient, quiet and reliable it has been adopted by industrial air compressor manufacturer’s to expand their product offering for their smaller, high-efficiency product line.

They operate on the principle of two intermeshing spirals or scrolls with one being stationary while the other rotates or orbits in relation to it.  They are mounted with 180° phase displacement between them which forms air pockets having different volumes.  Air enters through the inlet port located in the rotating/orbiting scroll which fills the chambers and as is moved along and compressed along the scroll surfaces.

scroll compressor finalSome of the key advantages of a Rotary Scroll Compressor are:

  • Pulsation free delivery due to the continuous flow from the suction port to the outlet port.
  • No metal to metal contact thereby eliminating the need for lubrication
  • Low noise levels
  • Fewer moving parts means less maintenance
  • Energy Efficient
  • Air cooled

The largest disadvantage is they are available in a limited range of sizes and the largest SCFM outputs are around 100 SCFM.

This is exactly where EXAIR shines, we offer 15 product lines of highly efficient & quiet point of use compressed air products and accessories to compliment their limited output volume of air.  All EXAIR products are designed to use compressed air efficiently and quietly, many of which reduce the demand on your air compressor which will help control utility costs and possibly delay the need to add additional compressed air capacity.

As an example, EXAIR’s Super Air Knives deliver exceptional efficiency by entraining ambient air at ratios of up to 40:1 and they are able to deliver an even laminar flow of air ranging from a gentle breeze to exceptionally hard-hitting force.

Super Air Knife
EXAIR’s Super Air Knife entrains ambient air at a 40:1 ratio!

EXAIR’s Super Air Amplifiers are able to entrain ambient air at ratio’s up to 25:1.  The model 120024 – 4″ Super Air Amplifier developes output volumes up to 2,190 SCFM while consuming only 29.2 SCFM of compressed air @ 80 PSI which can easily be operated on a 100 SCFM output compressor.

Super Air Amplifier
EXAIR Air Amplifiers use a small amount of compressed air to create a tremendous amount of air flow.

For your blow off needs EXAIR’s Super Air Nozzle lineup has an offering that will fit nearly any need or application you may have.  Nozzles are available in sizes from M4 x 0.5 to  1 1/4 NPT and forces that range from 2 ounces of force up to 23 Lbs at 12″ from the discharge.  We offer sixty two nozzles that could all be operated easily from the limited discharge or a rotary scroll compressor.

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Family of Nozzles

If you need to reduce your compressed air consumption or you are looking for expert advice on safe, quiet and efficient point of use compressed air products give us a call.  We would enjoy hearing from you!

Steve Harrison
Application Engineer
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Video Blog: Cleaning Gen4 Ionizing Bars

EXAIR’s Gen4 Super Ion Air Knife and Ionizing Bars are a great way to relieve static charges in your products and/or processes.  They are a very powerful, efficient design that will eliminate static charges and require only minimal maintenance to keep them performing at peak efficiency.

Check out the video below to see just how easy it is!

When you are looking for expert advice on your static relief application or any of our safe, quiet and efficient point of use compressed air products give us a call.   We would enjoy hearing from you!

Steve Harrison
Application Engineer
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Custom Products from EXAIR Meet Your Specifications

Since EXAIR manufactures and distributes our own products, we have the flexibility to provide custom products, special processing, unique packaging and more. If your process or specifications are something special, let us know and we will do our best to accommodate any special considerations you might need. Following is one example for a customer who purchases air guns.

Several months ago I received a call from a company that was looking for a specialized air gun.  This company was involved in the servicing of highly specialized measuring equipment and needed a safe, quiet, & efficient air gun that also had to be completely oil/contamination free.   This was to ensure no contamination would result from using the air gun on any of their equipment.  Ultimately this meant that every air gun component needed to be washed,  rinsed and dried to ensure there was no residual oils or dirt from manufacturing left on or in any component of the gun.

Our customer decided on the highly versatile Vari-Blast Compact Safety Air Gun with the award-winning Nano Super Air Nozzle, specifically models 1698SS and the 1698SS-6.  EXAIR presented a written process to the customer. This process explained how we would identify and manufacture their specific air gun in order to assure the customer that would receive a consistently clean air gun, every time.

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EXAIR’s Award Winning Nano Super Air Nozzle Performance Characteristics
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1110SS Specifications
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1698SS
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1698SS-6

Additionally the customer had specifications requiring special packaging as they were going to ship these globally to their service team members.  To ensure safe arrival no matter where they are shipped,  EXAIR provides special handling and packaging which exceeds their requirements.

Also, when you are looking for expert advice on safe, quiet and efficient point of use compressed air products give us a call.  We would enjoy hearing from you!

Steve Harrison
Application Engineer
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Super Air Wipe Vs. Block Type Air Wipe

When you need to cool, blow off or dry extruded objects there are several options available, however only the EXAIR Super Air Wipe delivers the performance, efficiency and versatility that most applications require!  In today’s blog we will contrast some of the differences between the EXAIR Super Air Wipe and block type air wipes.

The split-ring design of EXAIR’s Super Air Wipe offers easy clamping around the surface of the material moving through it and eliminates the need for time-consuming, cumbersome threading.  While Block Type Air Wipes are also of split design the diameter of the material drawn through it can typically only vary by approximately 1/16″!  In contrast the EXAIR Super Air Wipe is effective on materials that can range in size from approximately half the throat diameter up to within a fraction of an inch on the internal diameter.  This range can be as large as five to six inches in our largest Super Air Wipes.  The key is to ensure the material does not contact the Super Air Wipe.

Mounting the EXAIR Super Air Wipe is a snap, it can be accomplished by using either the 1/4 – 20 tapped holes on the downstream side or by utilizing a hard pipe compressed air supply line.  The access to these bolt holes makes it easy to change out in the event the production line runs several different sizes. If needed the included stainless steel 1/4-20 bolts can also be removed and longer bolts could be installed to mount from either side.

Connecting the EXAIR Super Air Wipe to your compressed air supply is straightforward.  For sizes up for 4″ throat diameter a stainless steel braided connecting hose is supplied pre-installed from the factory and a single 1/4″ FNPT inlet is used to supply the entire wipe.  For the 5″ up to 7″ throat diameter there is a single 1/4″ FNPT inlet on each half of the wipe which would need to be connected with compressed air.  Lastly, the 9″ and 11″ sizes from stock each have two 1/4″ FNPT inlet on each half of the wipe which would need to be connected to provide the appropriate flow for optimal performance.

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EXAIR Super Air Wipe features hinged design for trouble-free threading

Another very important consideration is the temperature of the material you are running.  EXAIR Aluminum Super Air Wipes are rated for temperatures up to 400°F (204°C) with the Stainless Steel models rated up to 800°F (427°C).    Typically, block air wipes are made from delrin or polypropylene with a replaceable wear liner,  unfortunately these materials do not tolerate higher temperatures like the EXAIR Super Air Wipes.

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EXAIR Super Air Wipe cooling an extrusion, high temperatures are not a problem!

To explain how the EXAIR Super Air Wipes work, reference the animation below: Compressed air flows through the inlet (1) of the Air Wipe into the annular chamber (2).  It is then throttled through a small ring nozzle (3) at high velocity.  This primary air stream adheres to the Coanda profile (4), which directs down the angled surface of the Air Wipe.  A low pressure is created at the center (5) inducing a high volume flow of surrounding air into the primary airstream.  As the airflow exits the slot, it creates a conical 360° ring of air that will attach to the surface of the material running through it (6) uniformly wiping the entire surface with the high velocity airflow.

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How The Super Air Wipe Works

While block style air wipes have a  fixed performance because they operate off a series of non-adjustable drilled holes, the EXAIR Super Air Wipe operates off an adjustable shim design.  As shown in the figure above the shim sets the gap opening of the ring nozzle (3).  The stock thickness of the stainless steel shim is .002″ (.05mm), shims can be stacked to provide a coarse adjustment in volumetric air flow.  Custom shim thicknesses are also available to tailor the performance to your needs.   The shim thickness coupled with a pressure regulator gives the Super Air Wipes adjustability from a gentle breeze to remove light debris or provide cooling all the way up to a forceful blast to remove more viscous fluids or provide quick cooling.

The EXAIR Super Air Wipe is 1.13″ (29mm) thick on all (11) Aluminum models that range in size from 3/8″ (10mm) to 11″ (279mm) throat diameter and all (5) Stainless Steel models that range in size from 1/2″ (50mm) to 4″ (102mm).

Super Air Wipe Family Photo

The Aluminum Super Air Wipe is available in 11 sizes 3/8″, 1/2″, 1″, 2″, 3″, 4″, 5″, 6″, 7″, 9″ & 11″; the Stainless Steel Super Air Wipe comes in 5 sizes, 1/2″, 1″, 2″, 3″ & 4″…all from stock!

So when you need to cool, blow off or dry extruded material or need expert advice on safe, quiet and efficient point of use compressed air products, give us a call.  We would enjoy hearing from you!

Steve Harrison
Application Engineer
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