Porous vs. Non-porous Material Selection

Published on by Al WooffittLeave a comment

EXAIR’s E-Vacs offer an excellent solution for a variety of applications such as pick and place, chucking, surface mounting, lifting, and vacuum forming.
When it comes to choosing the right model for your needs, there are a few key factors to keep in mind. While picking the correct vacuum cup size is crucial, and understanding the size and weight of the part is essential, one of the most important aspects is assessing the type of material you’re dealing with. In particular, is the material porous or non-porous?

Porous materials, as the name implies, contain numerous (very small) holes. This enables air to pass through when attempting to create a vacuum. It can be tricky when using an E-Vac. To tackle this issue, a high vacuum flow is necessary. In contrast, non-porous materials do not permit air to flow through, allowing for a higher vacuum level to be reached with a lower vacuum flow. If you’re aware of which category your material belongs to, we can choose the right E-Vac.

If you’re dealing with porous materials like paper, cardboard, or certain fabrics, we suggest using one of our vacuum generators that creates a low vacuum level along with a high vacuum flow. With vacuum levels reaching up to 21″ Hg and flows up to 18.5 SCFM, this type of E-vac generates more vacuum flow to tackle porosity and leakage. Plus, they can also lift or hold fragile materials, helping to avoid any warping or distortion of the surface from too much vacuum.

Cardboard – Photo by OpenClipart Vectors and licensed by Pixabay
Glass – Photo by dflamini and licensed by Pixabay

On the other hand, if your material is non-porous, such as glass, steel sheet, or plastic, you’ll need a generator that can create a high vacuum level with a lower vacuum flow. EXAIR’s non-porous high vacuum units can reach vacuum levels of up to 27″ Hg and vacuum flows of up to 15.8 SCFM. These vacuum generators provide the best holding capacity for heavy materials. You can find sizes that require as little as 2.3 SCFM of compressed air at 80 PSIG, and up to 30.8 SCFM for the largest and heaviest materials.

Once you’ve determined which vacuum generator is most suitable for your material, you will then need to select between our E-Vac accessories to complete your system. We offer different sizes and styles of vacuum cups, as well as mufflers (both standard and straight-through style). We also have auto-drain filters to ensure the compressed air supply is clean and moisture free. This will make your E-Vac system virtually maintenance free.

If you would like to talk to an Application Engineer to help you determine the best option for your application, give me a call!

Al Wooffitt
Application Engineer

Send me an Email
Find us on the Web
Like us on Facebook
Twitter: @EXAIR_AW

Controlling Temperature and Flow in a Vortex Tube

Published on by John BallLeave a comment

EXAIR has written many different articles about how Vortex Tubes work and the applications in which they are used.  The idea of making cold air without freon or moving parts is a phenomenon.  This phenomenon is the Vortex Tube.  It can generate cold air to a temperature as low as -50 oF (-46 oC).  In this article, I will explain the adjustment of the Vortex Tube to get different temperatures and cooling effects with reference to the Cold Fraction.

To give a basic background on the EXAIR Vortex Tubes, we manufacture them in three different body sizes: small, medium, and large.  These sizes can produce a range of cooling capacities, from 135 BTU/hr to 10,200 BTU/hr (34 Kcal/hr to 2,570 Kcal/hr).  The unique design utilizes a generator inside each Vortex Tube.  The generator controls the amount of compressed air that can enter the Vortex Tube as well as initiating the spinning of the air inside.  As an example, a medium-sized Vortex Tube, model 3240, will only allow 40 SCFM (1,133 SLPM) of compressed air to travel into the Vortex Tube at 100 PSIG (6.9 bar).  While a small Vortex Tube, model 3208, will only allow 8 SCFM (227 SLPM) of compressed air at 100 PSIG (6.9 bar).  EXAIR manufactures the most comprehensive range, from 2 SCFM (57 SLPM) to 150 SCFM (4,248 SLPM).

After the compressed air goes through the generator, the pressure will drop to slightly above atmospheric pressure.  (This is the “engine” of how the Vortex Tube works.)  The air will travel toward one end of the tube, where there is an air control valve, or Hot Air Exhaust Valve.  This side of the Vortex Tube will blow hot air.  This valve can be adjusted to increase or decrease the amount of air that leaves the hot end.  The remaining portion of the air is redirected toward the opposite end of the Vortex Tube, called the cold end.  By conservation of mass, the hot air and cold air flows will have to equal the inlet flow, as shown in Equation 1:

Equation 1:

Q = Qc + Qh

Q – Vortex Inlet Flow (SCFM/SLPM)

Qc – Cold Air Flow (SCFM/SLPM)

Qh – Hot Air Flow (SCFM/SLPM)

The percentage of inlet air flow that exits the cold end of a vortex tube is known as the Cold Fraction.  As an example, if the Hot Air Exhaust Valve of the Vortex Tube is adjusted to allow only 20% of the air flow to escape from the hot end, then 80% of the air flow is redirected toward the cold end.  EXAIR uses this ratio as the Cold Fraction; reference Equation 2:

Equation 2:

CF = Qc/Q * 100

CF = Cold Fraction (%)

Qc – Cold Air Flow (SCFM/SLPM)

Q – Vortex Inlet Flow (SCFM/SLPM)

EXAIR Vortex Tube Performance Chart

EXAIR created a chart to show the temperature drop and rise relative to the incoming compressed air temperature.  Across the top of the chart, we have the Cold Fraction, and along the side, we have the inlet air pressure.  As you can see, the temperature changes as the Cold Fraction and inlet air pressure changes.  As the percentage of the cold fraction becomes smaller, the cold air flow becomes colder, but the amount of cold air flow becomes less.  You may notice that this chart is independent of the Vortex Tube size.  So, no matter the size of the Vortex Tube that is used, the temperature drop and rise will follow the chart below.

How do you use this chart?  As an example, we can select a model 3240 Vortex Tube.  It will use 40 SCFM (1133 SLPM) of compressed air at 100 PSIG (6.9 Bar).  We can determine the temperature and amount of air that will flow from the cold end and the hot end.  For our scenario, we will set the inlet pressure to 100 PSIG, and adjust the Hot Exhaust Valve to allow for a 60% Cold Fraction.  Let’s say the inlet compressed air temperature is 68oF.  With Equation 2, we can rearrange the values to find the Cold Air Flow, Qc:

Qc = CF * Q

Qc = 0.60 * 40 SCFM = 24 SCFM of cold air flow

The temperature drop shown in the chart above is 86oF.  If the inlet temperature is 68oF, the temperature of the cold air is (68oF – 86oF) = -18oF.  So, at the cold end, we will have 24 SCFM of air at a temperature of -18oF.  For the hot end, we can calculate the flow and temperature as well.  From Equation 1,

Q = Qc + Qh or

Qh = Q – Qc

Qh = 40 SCFM – 24 SCFM = 16 SCFM

The temperature rise shown in the chart above is 119oF.  So, with the inlet temperature at 68oF, we get (119oF + 68oF) = 187oF.  So, we have 16 SCFM of air at a temperature of 187oF coming out of the hot end.

With the Cold Fraction and inlet air pressure, you can get specific temperatures for your application.  For cooling and heating capacities, flow and temperature can be used to calculate the correct Vortex Tube size for your application.  If you need help determining the proper Vortex Tube to best support your application, you can contact an Application Engineer at EXAIR.  We will be glad to help.

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

New Air Cradle for Quick and Efficient Air Gun Storage

Published on by Jordan T ShouseLeave a comment

EXAIR now offers the new Air Cradle Safety Air Gun Mount, a simple but innovative accessory designed to keep safety air guns and similarly sized tools within easy reach at workstations and machine centers. With its strong magnetic loop design, the Air Cradle provides a convenient, highly accessible hang point for safety air guns, helping improve workflow, minimize tool misplacement, and promote a more organized, efficient work environment across manufacturing, assembly, shipping, and other general shop applications.

The Air Cradle is a magnetic loop that securely holds a safety air gun or other often-used tools in place on any available magnetic surface, ensuring the tool remains at arm’s reach when needed most. Its versatile design allows operators to mount the cradle on equipment such as mills, lathes, cutoff saws, or any metal surface in a busy shop floor. The simplicity and effectiveness of the design mean that workers can instantly return tools to a designated location, reducing time spent searching for misplaced airguns and enhancing overall productivity. Capable of holding up to 10lbs, it’s a handy addition to any workstation.

Part of EXAIR’s extensive portfolio of useful accessories, the Air Cradle complements the company’s lineup of safety air guns and nozzles by offering a practical storage solution that reinforces proper tool handling and shop organization. Easy to install and use, the Air Cradle reflects EXAIR’s commitment to delivering reliable, quality-engineered solutions that help industrial teams work more safely and efficiently. Air Cradle prices start at $30.

If you have any questions about the air cradle or any of our Safety Air Guns, please reach out!

Jordan Shouse, CCASS

Application Engineer / Sales Operations Engineer

Send me an email
Find us on the Web 

Laminar vs. Turbulent Flow

Published on by jasonkirbyLeave a comment
If the object you’re blowing off is flat, the laminar air flow from a Super Air Knife is ideal. They come in lengths from 3 inches to 9 feet long.

EXAIR often differentiates between laminar and turbulent flow in relation to our blow-off products. To clarify, laminar airflow is notably more efficient in blow-off applications, as it reduces pressure drops, enhances product displacement, and minimizes noise levels when compared to turbulent airflow. Understanding these distinctions is essential for optimizing performance in various applications.

Laminar flow describes a type of airflow where the velocity and direction remain uniform throughout a designated volume of air. This phenomenon results in air movement that occurs in straight lines, aligning parallel to any solid surfaces present in the area.

Laminar airflow is effective in reducing turbulence. However, the introduction of devices or materials on surfaces can unintentionally create swirls within the workspace. This chaotic turbulent flow can disrupt tasks that require a dust-free environment, leading to potential contamination. Furthermore, obstructions such as items left inside enclosures can exacerbate this issue.

The Super Air Knife by EXAIR serves as a prime example of a product that delivers laminar airflow. This cutting-edge tool offers an efficient solution for tasks such as cleaning, drying, or cooling various components, webs, or conveyors. It produces a steady sheet of laminar airflow that applies a consistent force along its entire length, ensuring optimal performance for a wide range of applications.

Turbulent airflow is characterized by its unpredictable and chaotic fluid dynamics, standing in stark contrast to laminar flow, where fluids move in smooth, parallel layers. In turbulent conditions, the fluid’s speed and direction are in constant flux, leading to the development of eddies and swirls within the flow.

If you have questions about laminar or turbulent airflow, please do not hesitate to reach out.

Jason Kirby
Application Engineer
Email: jasonkirby@exair.com
Twitter: @EXAIR_jk