Going Outside The Box With Vortex Tubes

Among EXAIR’s comprehensive line of Intelligent Compressed Air Products, the Vortex Tube stands out as a unique, and fascinating, solution for a variety of applications requiring a flow of cold air:

  • Cabinet Cooler Systems: clean, cold air to protect electrical and electronic components housed in an enclosure.  Installs in minutes; no moving parts; reliable & maintenance free.
  • Cold Gun Aircoolant Systems:  Direct, focused flow of cold air to replace messy coolant in machining, cutting, drilling, grinding, etc., applications.  Integral magnet base for quick & easy installation; single or dual outlet hose kits; standard or High Power to meet any need.  Optimized flow for maximum cooling and freeze prevention.
  • Adjustable Spot Cooler: Similar to the Cold Guns in many ways, but with variable performance for specific applications.  Cold air to -30°F (-34°C) on demand.
  • Mini Cooler: Similar to the Cold Guns and Adjustable Spot Coolers – magnetic base mounting and single or dual outlet hose kits, but more compact.  Lower flows for smaller jobs.

Then there are the Vortex Tubes themselves…at the heart of all of these products, but perfectly capable all on their own.  In fact, in certain situations, “plain old” Vortex Tubes have been used to do the exact same jobs as all of the above products.  They can even be customized, in and of themselves, to meet specific installation, operation, and/or performance needs:

  • High Temperatures: It should come as no surprise that cold air is often needed because a heat-sensitive item is located in a high heat environment.
    • Vortex Tubes come standard with plastic Generators and Buna o-rings, which are good for ambient temperatures up to 125°F (52°C).
    • High Temperature Vortex Tubes are fitted with brass Generators and Viton o-rings for environments where the temperature can reach 200°F (93°C).
High Temperature Vortex Tubes are suitable for use in environments up to 200F (93C).
  • Preset temperature & flow: Many times, the ability to adjust the performance of a Vortex Tube is a big benefit, but occasionally it’s a liability.
    • I know none of your co-workers are like this (nor are mine) but I’ve heard of people who think they “know better” and are prone to tampering with something that is (or WAS) working just fine, thank you very much.
    • Perhaps you actually DO know better, through experimentation and experience, the optimal performance setting for your application.  Let’s say, for example, you install Vortex Tubes on a line of your products, and a technician has to “dial it in” to a specific Cold Fraction.
    • Any Vortex Tube can be fitted with a drilled orifice (or “Hot Plug”) to replace  the Hot Valve, which presets performance to a specific, non-adjustable value.  If you know the Cold Fraction you need, it’s as easy as that.  If not, it’s as easy as getting a stock Vortex Tube, setting the Cold Fraction where you want it, securing the Hot Valve in position (piece of tape works just fine,) and sending it in.
Preset Vortex Tubes feature a fixed plug, replacing the Hot Valve shown in this picture.

If you’ve got any other specific requirements – special materials, fittings, custom flow/temperature parameters, etc., give me a call; let’s talk.

Russ Bowman
Application Engineer
EXAIR Corporation
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Vortex Tube Cooling Capacities and Generators

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Vortex  Medium Generator

Vortex Tube Generators are the internal component that controls the volume of air entering the Vortex Tube and ultimately the volume of cool/cold air produced.

Vortex family
Vortex Family

EXAIR manufactures three sizes of Vortex Tubes, small, medium & large.  Each size can produce a range of cooling power that can be changed by installing a different generator that will change the volume output capability of that Vortex Tube. The generators for small size vortex tubes can operate at 2, 4 or 8 SCFM (maximum cooling power of 550 BTU/HR),  generators for the medium size at 10, 15, 25, 30, or 40 SCFM (maximum cooling power of 2,800 BTU/HR) and the generators for the large size operate at 50, 75, 100 or 150 SCFM (maximum cooling power of 10,200 BTU/HR).  The Vortex Tube is sold with one generator installed.

The generators are marked with a number and a letter.  The number indicates the capacity (SCFM of air consumption) and the letter indicates the type of operation (“R” for maximum refrigeration or “C” for maximum cold temperature).  The maximum refrigeration (“R”) works best when the majority of the inlet air is exhausted out the cold end of the Vortex Tube. They work most efficiently with smaller temperature drops and larger volume of flow than the other generators. The maximum cold generators (“C”) can produce temperatures below 0°F, and work best when the minority of the inlet air is exhausted out the cold end of the Vortex Tube. The volume of cold air produced is less but you will experience greater temperature drops.

How A Vortex Tube Works

If a different cooling capacity is desired, other generators are available by either purchasing them individually or by purchasing one of the (3) highly versatile Vortex Tube Cooling Kits designated as the 3908 (small), 3930 (medium) or 3998 (large).  The Kits include the Vortex Tube, Filter Separator, Vinyl Tubing, Tubing Adapter, Tube Clamps, Cold End Muffler (Optional Hot End Muffler Available) and Both “R” & “C” Generators.

Vortex kit
EXAIR Medium Vortex Kit Includes: Vortex Tube, Filter Separator, Vinyl Tubing, Tubing Adapter, Tube Clamps, Cold End Muffler (Optional Hot End Muffler Available, Sold Separately) and Both “R” & “C” Generators (10, 15, 25, 30, or 40 SCFM).

If you would like to discuss Vortex Tubes, their Generators, or any of EXAIR’s safe, quiet & efficient compressed air products, I would enjoy hearing from you…give me a call.

Steve Harrison
Application Engineer
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Vortex Tubes: What is a Cold Fraction & How to use it to Your Benefit

Vortex Tubes

EXAIR has wrote many different articles about how Vortex Tubes work and the applications in which they are used.  The idea of making cold air without any freon or moving parts is a phenomenon.  This phenomenon 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 in reference to the Cold Fraction.

To give a basic background on the EXAIR Vortex Tubes, we manufacture three different sizes; small, medium, and large.  These sizes can produce a range of cooling capacities from 135 BTU/hr to 10,200 BTU/hr.  The unique design utilizes a generator inside each Vortex Tube.  The generator controls the amount of compressed air that can enter into the Vortex Tube.  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-sized 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).

Vortex Tube Exploded View

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 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 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)

Cold Fraction is the percentage of air that flows out the cold end of a Vortex Tube.  As an example, if the control 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 has to be 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 Flow (SCFM/SLPM)

Vortex Tube Charts

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 also the air flow becomes less.  You may notice that this chart is independent of the Vortex Tube size.  So, no matter the generator size of the Vortex Tube that is used, the temperature drop and rise will follow the chart above.

Vortex Tube Example

How do you use this chart?  As an example, a model 3240 Vortex Tube is selected.  It will use 40 SCFM of compressed air at 100 PSIG.  We can determine the temperature and amount of air that will flow from the cold end and the hot end.  The inlet pressure is selected at 100 PSIG, and the Hot Exhaust Valve is adjusted to allow for a 60% Cold Fraction.  Let’s use an inlet compressed air temperature to be 68 oF.  With Equation 2, we can rearrange the values to find Qc:

Qc = CF * Q

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

The temperature drop from the chart above is 86 oF.  If we have 68 oF at the inlet, then the temperature is (68 oF – 86 oF) = -18 oF.  So, from the cold end, we have 24 SCFM of air at a temperature of -18 oF.  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 from the chart above is 119 oF.  So, with the inlet temperature at 68 oF, we get (119 oF + 68 oF) = 187 oF.  At the hot end, we have 16 SCFM of air at a temperature of 187 oF.

With the Cold Fraction and inlet air pressure, you can get specific temperatures for your application.  For cooling and heating capacities, these values can be used to calculate the correct Vortex Tube size.  If you need help in 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

Controlling Temperature and Flow in a Vortex Tube

VT_air2

A few weeks ago, we looked at the Vortex Tube and provided a general overview of the device (see that blog here.)  In a nutshell – a Vortex Tube uses an ordinary supply of compressed air as a power source, creating two streams of air, one hot and one cold – resulting in a low cost, reliable, maintenance free source of cold air for spot cooling solutions.

One of the features of the Vortex Tube is that the temperature of the cold air and the cold air flow rate is changeable. The cold air flow and temperature are easily controlled by adjusting the slotted valve in the hot air outlet.

Vortex Tube Hot Valve Adjustment
Hot Valve Adjustment for a Vortex Tube

Opening the valve (turning it counterclockwise) reduces the cold air flow rate and the lowers the cold air temperature.  Closing the valve (turning it clockwise) increases the cold air flow and raises the cold air temperature.

VT Adjustment Table

As with anything, there is a trade off – to get higher a cold air flow rate, a moderate cold air temperature is achieved, and to get a very cold air temperature, a moderate air flow rate is achieved.

An important term to know and understand is Cold Fraction, which is the percentage of the compressed air used by the Vortex Tube that is discharged through the Cold End.  In most applications, a Cold Fraction of 80% produces a combination of cold flow rate and and cold air temperature that results in the maximum refrigeration or cooling output form a Vortex Tube.

For most industrial applications – such as process cooling, part cooling, and chamber cooling, maximum refrigeration is best and the 32XX series of Vortex Tubes are preferred.  For those applications where ‘cryogenic’ cooling is needed, such as cooling lab samples, or circuit testing, the 34XX series of Vortex Tube is best.

To set a Vortex Tube to a specific temperature, simply insert a thermometer into the cold air exhaust and adjust the hot valve.  Maximum refrigeration, at 80% Cold Fraction, is achieved when the cold air temperature drop is 50°F (28°C) from the incoming compressed air temperature. See the video posted here for measuring and lowering and the cold air temperature.

For those cases when you may be unsure of the required cold air flow rate and cold air temperature to provide the needed cooling in an application, we would recommend an EXAIR Cooling Kit.  The Cooling Kit contains a Vortex Tube, Cold Air Muffler, Air Line Filter, and a set of Generators that will allow for experimentation of the full range of air flows and temperatures possible.

gh_VTcoolingkit_750x696p
EXAIR Vortex Tube Cooling Kit

To discuss your application and how a Vortex Tube or any EXAIR Intelligent Compressed Air Product can improve your process, feel free to contact EXAIR, myself, or one of our other Application Engineers. We can help you determine the best solution!

Brian Bergmann
Application Engineer

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Vortex Tube Overview

VT_air2

A Vortex Tube uses an ordinary supply of compressed air as a power source, creating two streams of air, one hot and one cold – resulting in a low cost, reliable, maintenance free source of cold air for spot cooling solutions.

The EXAIR Vortex tubes are made of stainless steel, which provides resistance to wear, corrosion and oxidation – ensuring years of reliable, maintenance free operation

How_A_Vortex_Tube_Works

The cold air flow and temperature are easily controlled by adjusting the slotted valve in the hot air outlet.  Opening the valve reduces the cold air flow and the cold air temperature.  Closing the valve increases the cold air flow and and the cold air temperature.

EXAIR Vortex Tubes come in three sizes. Within each size, a number of flow rates, which are dictated by a small internal generator, are available. Selection of the appropriate Vortex Tube can be achieved either by knowing the BTU/hr (Kcal/hr) requirements or the desired flow and temperature requirements. Selection is then based on the specification table (BTU/hr or Kcal/hr is known) or the performance tables (flow and temperature is known.)

Capture
Vortex Tube Specification Tables

 

Cold Fraction
Vortex Tube Performance Tables

The performance of a Vortex Tube is reduced with back pressure on the cold air exhaust. Low back pressures up to 2 PSIG ( 0.1 Bar) will not change performance and a 5 PSIG (0.3 Bar) will change the temperature drop by approximately 5°F (2.8°C)

The use of clean air is essential, and filtration of 25 microns or less is recommended.  EXAIR offers filters with 5 micron elements and properly sized for flow.

A Vortex Tube provides a temperature drop to the incoming supply air.  High inlet temperatures will result in a corresponding rise in the cold air temperature.

EXAIR offers mufflers for both the hot and cold air discharge.  If the cold air is ducted, muffling may not be required.

For best performance, operation at 80 to 110 PSIG (5.5 to 7.6 Bar) of supply pressure is recommended. The Vortex Tubes have a maximum pressure rating of 250 PSIG (17.2 Bar) and a minimum requirement of 20 PSIG (1.4 Bar)

To discuss your application and how a Vortex Tube or any EXAIR Intelligent Compressed Air Product can improve your process, feel free to contact EXAIR, myself, or one of our other Application Engineers. We can help you determine the best solution!

Brian Bergmann
Application Engineer

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Twitter: @EXAIR_BB

The difference between a mold and a die? EXAIR Vortex Tubes can help in both applications.

Vortex Tubes

What is the difference between a mold and a die?  A mold is a form that shapes a liquid material into a sold piece.  It requires time for the liquid material to harden and take shape.  A die is a form that shapes a solid piece through brute force.  This can be either through stamping or through metalworking.  I will illustrate examples of both and how the Vortex Tubes were able to improve cycle times.

Mold Example: An automotive company was making plastic gas tanks through blow molding.  Liquid plastic is oozed into a mold, and just before it hardens, air is injected to create a cavity inside while the mold shapes the gas tank.  The warm tank was then placed in a fixture to cool.  Once hardened, then it could be handled and processed for the next operation.  The problem was that it took 3 minutes to harden; creating a bottleneck.  EXAIR suggested two pieces of a model 3250 Vortex Tubes to blow cold air into each cavity of the gas tanks.  This cooling process decreased the hardening time from 3 minutes to 2 minutes.  This improved productivity by 33%.

Movie Film

Die Example: A reel manufacturer was using a die stamping machine that would create the sprocket holes in the outer edge of a 35mm film.  These holes were used to advance the reel strip through printers, projectors, and processing machines.  The stamping die would heat up from the brute force of the cutting edge making the hole.  This would cause issues with the quality of the plastic film reel.  For this application, EXAIR recommended the model 5315 Cold Gun System.  This product is a modified version of the Vortex Tube that includes a magnetic base, muffler, and a dual flexible outlet hose.  They would blow the cold air on both sides of the die to keep them cool.  They were able to increase speeds and also noticed that the die stayed sharper 20% longer before they had to be reworked.

1/4 ton of refrigeration in the palm of your hand

Both customers were intrigued with the EXAIR Vortex Tubes as they can generate cold air by only using compressed air.  They do not use refrigerants, moving parts, or motors to wear.  These simple devices are very compact and can fit into tight places.  EXAIR Vortex tubes offer cooling capacities from 275 BTU/hr to 10,200 BTU/hr.  They can be configured in different styles to best suite your application.

Whether you are using a mold or a die in your process, a Vortex Tube may benefit you.  Heat causes slowdowns and bottlenecks.  With both customers above, the EXAIR Vortex Tubes were able to increase their productivity and decrease their downtime.  If you believe that temperature is affecting your process, you can contact an Application Engineer to discuss how we can help.

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

 

Photo:  Reel Film Cinema By JanBabyCreative Commons CC0 Public Domain

EXAIR’s High Power Cold Gun Keeps Saw Blade Cool in Mining Operation

Our distributor in Peru recently contacted me with an application they were working on with a customer of theirs that deals in the mining industry. They are one of the largest gold mining companies in South America and were looking for a means of keeping their saw blades cool without having to use any type of coolant or water.

In this specific application, they had been using water to maintain the temperature of the blade while cutting. While this did work, it created quite a mess and also resulted in product contamination. The water on the floor presented a slipping hazard and production would have to periodically be halted so that someone could come by and clean the mess off of the floor. So, not only were they creating a contamination issue, but also a safety concern as well as lost production time.

IMG_20180613_094120_HDR
Cold Guns installed

Our distributor introduced them to EXAIR and our line of Cold Gun Spot Cooling Products. By replacing the water cooling with (2) Model 5230 Cold Gun systems, they were able to maintain the temperature of the blade at 24°C (75°F), well within their specifications. This allowed them to completely eliminate the need for water as a cooling method, improving their worker safety as well as increasing production.

Efixo Demo Cold Gun.png1

EXAIR’s Cold Gun utilizes Vortex Tube technology to create two streams of air: one hot and one cold. The hot air is muffled and exhausted, while the cold air is also muffled and ducted to deliver a cold stream of air directly onto the material needing to be cooled. With only a supply of clean, dry compressed air required to operate, installation is quick and easy. Since the Cold Gun has no moving parts to wear out, there’s also no maintenance required so long as the Auto-Drain filter included in the kit is installed upstream of the Cold Gun.

If you’re tired of dealing with messy water-based cooling systems or equally messy coolants, give an Application Engineer a call today and try out a Cold Gun. With our Unconditional 30 Day Guarantee, there’s absolutely no risk to do so!

Tyler Daniel
Application Engineer
E-mail: TylerDaniel@exair.com
Twitter: @EXAIR_TD