Vortex Tubes – The Basics, And Beyond

The Vortex Tube might be just about the most interesting compressed air device around.  They have no moving parts, and they don’t need any but a compressed air supply, which they ‘split’ into a hot air stream, and a cold air stream.

EXAIR Vortex Tubes come in three sizes – Small, Medium, and Large – and 24 distinct Models across those three sizes.  They’re all in stock, along with Hot & Cold Mufflers (for sound level reduction,) Automatic Drain Filter Separators (to keep the air supply clean & moisture free,) Oil Removal Filters (to coalesce any trace of oil from the air supply,) and Solenoid Valves & Thermostats (to automate operation.)

From left to right; a few value added accessories for your Vortex Tube: Hot Muffler, Cold Muffler, Automatic Drain Filter Separator, Oil Removal Filter, and Solenoid Valve/Thermostat Kit.

The Vortex Tube, right out of the box, is easily adaptable to a wide range of cooling (or heating) applications.  If your needs are specific, though, we can customize a Vortex Tube to meet them:

  • Material of construction: our stock Vortex Tubes are made of 303SS and are equipped with a plastic Generator and Buna o-ring.
    • For high temperature (>125F ambient) applications, we can install a brass Generator and Viton o-ring, suitable for ambient temperatures up to 200F.
    • If the environment is particularly aggressive, or if industry codes (I’m looking at you, food & pharma) call for it, we can also make them out of other materials.  We’ve, for instance, made them out of 316SS, complete with material certifications, when needed.
  • Flow & temperature: the Hot Valve can be opened or closed to dial in a particular Cold Fraction (that’s the percentage of the supply air which is directed to the cold end.)  If you know what flow rate and temperature you want, we can replace the Hot Valve with a non-adjustable plug, so your Vortex Tube’s cold flow is only dependent on the compressed air supply temperature and pressure.
  • Accessories: if you’re looking for features like a magnetic base, or a flexible cold air hose, you might consider an Adjustable Spot Cooler.  If you like the idea of tool-free change of air flow/temperature, that’s definitely the way to go.  If you want those other options, and don’t mind using a screwdriver to adjust the Cold Fraction, those other options are compatible with any Medium Vortex Tube.
Model 3925 Adjustable Spot Cooler

These are just a few of the most common possibilities for customizing a Vortex Tube.  If you have a spot cooling application you’d like to discuss, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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Spot Cooling

A new solution to an old problem. Heat build up on dry machining operations reduces tool life and machining rates. The Cold Gun Aircoolant System produces a stream of clean, cold air at 50°F (28°C) below supply air temperature. Operation is quiet and there are no moving parts to wear out. It will remove heat to prolong tool life and increase productivity on machining operations when liquid coolants cannot be used.

The Cold Gun is also an alternative to expensive mist systems. It eliminates the costs associated with the purchase and disposal of cutting fluids and worker related health problems from breathing airborne coolants or slipping on wet shop floors.

The standard Cold Gun and High Power Cold Gun incorporate a vortex tube to convert an ordinary supply of compressed air (1) into two low pressure streams, one hot and one cold. The Cold Gun’s hot airstream is muffled and discharged through the hot air exhaust (2). The cold air (3) is muffled and discharged through the flexible hose (4), which directs it to the point of use. Easy mounting and portability are provided through the use of an attached magnetic base (5).

Applications include tool sharpening, drill and cutter grinding, drilling, band saw cooling, plastic machining and setting adhesives. 

EXAIR offers two types, the Cold Gun and the High Power Cold Gun.  The High Power Cold Gun blows twice the amount of cold air as the Cold Gun which doubles the cooling capacity.  They come standard with either a Single Point or a Dual Point Hose Kit with a cone and flat nozzle.  All systems come with a magnetic base and a filter separator.  The magnetic base makes this device simple to attach to your machine and start using. 

Jordan Shouse
Application Engineer

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Vortex Tubes: What is a Cold Fraction?

Have you ever needed a source of cold air but don’t want to invest in a costly chiller? INTRODUCING Vortex Tubes! Vortex Tubes use compressed air and contain no moving parts to create a cold and hot stream of air from either end of the device. Using the valve located on the hot stream a vortex tube can achieve temperatures as low as -50°F (-46°C) and temperatures as high as 260°F (127°C).

When the vortex tube is supplied with compressed air the air flow is directed into the generator that causes spin into a spiraling vortex at around 1,000,000 rpm. This spinning vortex flows down the neck and wall of the hot tube. The control valve located on the end of the hot tube allows a fraction of the hot air to escape and what does not escape reverses direction and travels back down the center of the tube and exhausts out of the cold end. Inside of the low-pressure area of the larger outer warm air vortex, the inner vortex loses heat as it flows back to the cold end of the vortex and as it exits the vortex expels cold air. The absolute temperature drop that occurs during this process is going to be controlled by the cold fraction of the Vortex Tube and the supply pressure.

The brass screw used to control the cold fraction of a vortex tube

The cold fraction is defined as the amount of the inlet supply air that will exit out of the cold end of the vortex tube. An example would be if I had 10 SCFM supplied to a vortex tube with 60% cold fraction, then 6 SCFM would be exiting the cold discharge. Cold based on the amount of air you allow out of the hot end of the vortex tube you can control the temperature drop of the cold air. A smaller cold fraction which only allows a small amount of air to exit the cold discharge will result in a larger temperature drop; and vise versa a larger cold fraction will result in a much smaller temperature drop.

Table the shows the temperature drop and rise in correlation with the cold fraction and pressure

Here a EXAIR we have designed our vortex tubes to operate optimally at both a high cold fraction and a low cold fraction. The 32XX series designed to give you the best refrigeration, which means it will work well for cold fractions ~60% – 80%. This will give you a smaller temperature drop with more air flow which allows you to keep things cool much easier. This contrasts with the 34XX series which is designed more optimal performance at lower temperatures; this means the optimal cold fraction would be ~20% to 40%. Cold fractions this low will produce very little air flow but the temperature will be very cold (as low as -50°F). This is useful if you need to get an item down to a very low temperature.

If you have any questions about compressed air systems or want more information on any of EXAIR’s products, give us a call, we have a team of Application Engineers ready to answer your questions and recommend a solution for your applications.

Cody Biehle
Application Engineer
EXAIR Corporation
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Cold Gun Replaces Inefficient and Ineffective Open Pipe

In any machining operation, tool wear is an inevitability. Cutting tools heat up due to friction and this heat contributes to premature tool wear. As tooling wears, poor tolerances and dimensional inaccuracy are common. Additionally, as the cutting edge dulls increased cutting force is required which further increases the amount of heat generated and exacerbates the problem.

Coolants can be used to reduce friction and help mitigate some of the wear, but then you’re left with the mess that coolant brings along with it both on the part and in the machine itself. What if I were to tell you that there’s a way to mimic the effects of coolant, but without all of the mess? All of this can be achieved with a supply of compressed air and one of EXAIR’s Cold Gun Systems.

HP_coldgun_2007finalist

I recently worked with a metalworking company on replacing several open-pipe blowoffs on their CNC machines with EXAIR Cold Guns. The open pipes were not effective at keeping the tooling cool, but did a decent job of blowing away chips. Premature tool wear was leading to increased downtime and slowing production as they were frequently having to replace the tooling. Not to mention, these blowoffs were extremely loud and forced anyone on the shop floor to be wearing in-ear and over-the-ear hearing protection.

Each of their CNC machines had one open-line coolant hose or similarly sized open tube blowing compressed air onto the tool. Temperatures in the facility get fairly warm in the summer and this was having little to no impact. They didn’t want to deal with the mess that comes along with coolant, so they looked to EXAIR for a solution. They ended up installing (1) 5215 Single Point Cold Gun System for trial on one of their machines.

Immediately they noticed the reduction in sound as the Cold Gun operates at just 70 dBA, but they also noticed a 20% reduction in tool wear compared to the open-air lines after a short time in operation. It didn’t entirely eliminate the need for hearing protection as there are other processes occurring, but it did lower it to a point that they weren’t forced to use both in-ear and over-the-ear protection.

EXAIR’s Cold Gun was a Product of the Year finalist in 2007. Using only a source of compressed air, the Cold Gun and High Power Cold Gun produces a stream of clean, cold air 50° (28°C) below your compressed air supply temperature. The Cold Gun is very quiet at only 70dBA and has no moving parts to wear out. Just supply it with clean, dry compressed air and its maintenance free!

The Cold Gun has been preset to achieve maximum refrigeration. This prevents the Cold Gun from freezing up during use and optimizes the gun’s cooling capacity. The Cold Gun is an ideal alternative to messy and expensive coolant mist systems. It eliminates the cost of purchase and disposal of cutting fluids as well as worker related health problems from breathing airborne coolant or slipping on wet floors. Replacing a coolant-based system also eliminates the need for secondary cleaning operations after milling or drilling.

If you have an application that you believe would be better served by the use of an EXAIR Cold Gun, give us a call.

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