Month: July 2023

Air Compressors: Centrifugal Type.

Published on by John BallLeave a comment

There are two main ways to compress air for supplying pneumatic systems; Positive Displacement and Dynamic.  Positive Replacement reduces the volume of air within a confined space to generate pressure.  The dynamic type raises the air pressure by using kinetic energy and velocity with rotating impellers that continuously brings in airflow.  In this blog, I will cover the centrifugal type of the dynamic branch. 

As mentioned, the centrifugal compressor works by transforming kinetic energy and velocity into pressure.  Ambient air passes through guide vanes into the center of a rotating Impeller with radial blades and is then pushed outward by a centrifugal force. This radial velocity of air results in an increase in pressure due to kinetic energy.  Let’s look at the equation for kinetic energy in Equation 1:

Equation 1: 

K = ½ * m * V2  

K – Kinetic Energy (J)

m – mass (Kg)

V – velocity (m/s)

As you can see, the energy increases with the square of the velocity.  How do we increase the velocity?  Let’s look at Equation 2:

Equation 2:

V = w * r

V – linear velocity (m/s)

w – angular velocity (rad/sec)

r – radius (m)

As you can see, as the air travels along the impeller towards the outside, the radius increases.  Since the rotations per second are constant, the velocity will increase.  In combination with Equation 1, you can see how the energy will increase, thus increasing the pressure. 

 With the increase in pressure, you will get an increase in heat.  It is a natural occurrence with air compressors.  Heat from the centrifugal compressor is dissipated with heat exchangers before moving onto the next stage.  Multiple stages are required to raise the pressure to a sufficient level for typical industrial plant requirements.  The most common centrifugal air compressors have two to four stages to generate pressures up to 100 to 150 PSIG.  Centrifugal compressors are near the middle of the road regarding efficiency.  Their typical operating cost is 16 to 20 kW/100 CFM. 

Advantages:

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

Disadvantages:

  • Costs more Initially
  • Requires specialized maintenance

No matter the type of air compressor that you use, they are very costly to operate.  To help you use them efficiently and safely, EXAIR offers a range of products that can clean, cool, blow, conserve, and convey.  This would include our Super Air Knives, Super Air Nozzles, Safety Air Guns, Cabinet Coolers, and much more.  If you want to save energy, increase safety, and cut costs no matter what size air compressor you have; you can contact an Application Engineer at EXAIR.  We will be happy to help you. 

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

Images Courtesy of the Compressed Air Challenge

EXAIR’s External Mix Atomizing Spray Nozzles For High Flow Rates and Liquids Over 300 cP

Published on by Tyler DanielLeave a comment

EXAIR’s Air Atomizing Spray Nozzles are used to atomize fluids in a wide range of different spray patterns. They utilize a small amount of compressed air which mixes with the liquid supply to create a fine mist of atomized liquid. EXAIR manufactures Air Atomizing Spray Nozzles in (3) different varieties: Internal Mix, External Mix, and Siphon Fed. Siphon nozzles are applicable for processes where the liquid cannot be pressurized, possessing the ability to siphon liquids up to 36″ or be gravity fed. Internal Mix nozzles produce the finest atomization and are ideal for liquids with a viscosity below 300 cP. For this blog, I’m going to focus on just the External Mix variety.

On all External Mix Atomizing Nozzles the volume of liquid is easily adjusted through the valve stem on the standard Atomizing Nozzle, or by regulating the liquid pressure (the only option with the No-Drip style). Increasing the liquid pressure will result in an increased liquid flow rate. The External Mix nozzles have the highest flow rates and can be used with liquids with a viscosity greater than 300 cP. Since the air and liquid are mixing just outside the nozzle, thicker liquids have a lesser chance of clogging in the nozzle. Both the liquid stream and the air stream will come into contact with each other just outside both the air and liquid caps. The compressed air breaks the liquid up into very small particles, allowing you to use much less liquid than a liquid only nozzle.

This makes them very effective in applications that utilize expensive paints, oils, or other liquids. Rather than wasting the expensive materials, the nozzle can be set to precisely dispense only what is necessary to achieve a successful application. The External Mix Atomizing Nozzle is available in the standard configuration as well as the No-Drip style. The No-Drip Atomizing Nozzle is used in a variety of applications where any liquid dripping from the nozzle after the air supply has shut off would cause a problem. This is common in painting applications where any paint dripping would affect the quality.

The External Mix Atomizing Nozzle is available in (3) different sizes: 1/8” NPT, ¼” NPT, and ½” NPT. If your application could benefit from utilizing a fine atomized spray of liquid look no further than EXAIR’s Air Atomizing Nozzles. With all sizes and configurations available from stock, we can get one out to you quickly!  

Tyler Daniel, CCASS

Application Engineer

E-mail: TylerDaniel@EXAIR.com

Twitter: @EXAIR_TD

ATEX Rated Cabinet Cooler Systems Now Available From EXAIR!

Published on by Russ BowmanLeave a comment

In 1815, Sir Humphrey Davy patented an oil lamp for use in coal mines, and coincidentally pioneered the movement to provide safe and reliable products for use in explosion-prone environments. In the days before electricity, miners used lamps that burned fuel oil for lighting. The problem with that was, deposits of underground coal are almost always accompanied by methane gas pockets which, when mixed with coal dust in proximity to an open flame, created terrible and deadly explosions. Davy’s design incorporated a brass net around the wick chamber that let the light out, and let oxygen (necessary for combustion of the fuel oil) in, but if methane entered the wick chamber, it’d extinguish the flame and prevent ignition of the gas outside the lamp.

Industrial growth and the proliferation of electricity that (literally) powered it introduced new hazards in a number of industries other than just mining…which grew exponentially through the 19th century, since coal was the main fuel in electric generating plants. As hazards were identified (usually, unfortunately, by a tragic accident), new and safer products were developed, and eventually, industry professionals implemented controls & standards to make sure these new and safer products were designed, manufactured, and used for the prevention of future tragic accidents.

In North America, the National Electrical Code’s (NEC) system of Classes and Divisions specifies requirements of electrical product testing & use to ensure safety in this regard. In 2014, the European Union created the ATEX Directive, which specifies similar (but not identical) requirements, also aimed at mitigating explosion risks in industrial environments. In 2019, EXAIR introduced our HazLoc Cabinet Cooler Systems, which comply with certain NEC requirements, and we just recently introduced ATEX Cabinet Cooler Systems to comply with that directive.

Both the HazLoc (left) and ATEX Cabinet Cooler Systems are available from stock in NEMA 4 and NEMA 4X ratings.

Like our HazLoc Cabinet Cooler Systems, their ATEX counterparts have been subject to stringent UL testing to ensure compliance with the ATEX Directive. They’re approved for use in areas defined by the Directive as:

  • Zone 2 (an atmosphere where a mixture of air and flammable substances in the form of gas, vapour or mist is not likely to occur in normal operation, but if it does occur, will persist for a short period only) and
  • Zone 22 (an atmosphere where a mixture of air and flammable substances in the form of powder or dust is not likely to occur in normal operation, but if it does occur, will persist for a short period only.)

This fall, EXAIR will celebrate 40 years of dedication to safety and efficiency in engineering & manufacturing compressed air products for a wide range of applications. If you’d like to find out how our Cabinet Cooler Systems – or any of our Intelligent Compressed Air Products – can increase safety and efficiency, and lower sound levels for your compressed air usage, give me a call.

Russ Bowman, CCASS

Application Engineer
Visit us on the Web
Follow me on Twitter
Like us on Facebook

The EXAIR Flat Super Air Nozzles; features and benefits

Published on by John BallLeave a comment
Flat Nozzle Blow-off Kit

The EXAIR Flat Super Air Nozzles are manufactured to blow a wide, forceful stream of air.  Their engineered design creates a high-velocity, laminar air stream with minimal air consumption and low noise.  They come in two widths; 1” (25mm) and 2” (51mm).  EXAIR offers a standard Flat Super Air Nozzle and a High Force Flat Super Air Nozzle in two different materials: zinc-aluminum alloy and 316 stainless steel.  And with a metal construction, breakage is not a concern, and performance is not sacrificed even in the harshest of environments.  The unique patented shims inside the EXAIR Flat Super Air Nozzles will give you three improvements to the design and function.  First, they come in different thicknesses to create a wide range of forces.  In conjunction with a regulator, you can “dial” in the correct amount of force from a breeze to a blast without overusing your compressed air system.  The patented design also allows an even flow across the entire width of the air nozzle.  Lastly, the design helps to entrain the free ambient air; so that less compressed air is required; saving you money.  The EXAIR Flat Super Air Nozzles are effective in uniform blowing with safety and efficiency in mind.

Flat Super Air Nozzles have replaceable shims to vary performance.

To expand more on force adjustments with the Flat Super Air Nozzles, EXAIR has an easy way to change the shim to better suit your application.  You can increase or decrease the force of the nozzle by just removing two screws and changing the thickness of the shim inside.  EXAIR offers a variety pack called a Shim Set to give you a range of forces with the nozzles.  For the standard Flat Super Air Nozzle, they come stock with a 0.015” (0.38mm) shim for both the 1” and 2” sizes.  The corresponding Shim Sets will include a 0.005” (0.13mm), 0.010” (0.25mm), and 0.020” (0.51mm) shim.  The High Force Flat Super Air Nozzles will come standard with a 0.025” (0.64mm) shim, and the Shim Set will include a 0.020” (0.51mm) and a 0.030” (0.76mm) thick shim.  This is a unique feature, as the competitive plastic flat nozzles do not have this option. 

What can make the Flat Super Air Nozzles even better?  Flexibility.  The Stay Set Hoses can be added for positioning and repositioning the Flat Super Air Nozzles.  They are designed to manually move the nozzle to accurately target the air stream.  They allow for maneuverability, and once positioned, the Stay Set Hose will hold the nozzle in place.  They come in different lengths, from 6” (152mm) to 36” (914mm).  We carry two different styles of connections to adapt to the Flat Super Air Nozzles.  You can select the different lengths of Stay Set Hoses for the Flat Super Air Nozzle from the model number makeup sheet below.

EXAIR can also offer a Magnetic Base to your Stay Set Hoses and Flat Super Air Nozzles.  The Magnetic Base has a powerful magnet on the bottom to securely attach the blow-off system vertically or horizontally.  This feature is great if you need to move the nozzles to different locations in your application.  EXAIR manufactures a one-outlet and a two-outlet design.  Each outlet has a ¼ turn valve to manually turn on or off the nozzle.  To add this product to the Flat Super Air Nozzle and the Stay Set Hose, you can use the model number makeup sheet below for simplicity.

With the EXAIR Flat Super Air Nozzles, you can take advantage of their durability, safety, and efficiency for your blow-off devices.  In addition, you can build a system that will best suit your requirements by adding Stay Set Hoses and/or Magnetic Bases.  With these combinations grouped under one model number and in stock for quick shipments, it makes it easy to purchase from EXAIR.  And just to let you know if you are within the U.S. or Canada, they come with a 30-day unconditional guarantee to try them out.  If you need any help with drawings, performance, or setup of our Flat Super Air Nozzles or how to build an optimum blow-off system, you can speak with an Application Engineer at EXAIR.  We will be happy to help you.

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