Controlling Temperature And Flow Of An EXAIR Vortex Tube

Published on by Russ Bowman

If you need a reliable, consistent flow of cold air, look no further than the EXAIR Vortex Tube:

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

Getting the performance you want comes down to answering two simple questions:

What temperature do I need? 

Vortex Tubes produce a DROP in temperature, so your compressed air supply temperature is our starting point to determine what the actual cold air temperature will be.  The magnitude of the temperature drop is dependent on two factors:

  • Compressed air supply pressure – the higher the pressure, the higher the temperature drop.
  • Cold Fraction setting of the Vortex Tube – this is the percentage of the air supply that’s directed to the cold end.  The same temperature drop is produced, regardless of model, for a given Cold Fraction.  The lower the Cold Fraction, the greater the temperature drop (and hence, the lower the air temperature.)

EXAIR has two distinct series, or types, of Vortex Tubes:

3200 Series are used when Cold Fractions above 50% are desirable.  This provides maximum refrigeration…high flows and temperature drops that are optimal for many spot cooling applications such as tool cooling, setting hot melt adhesives, quick cooling of soldering/brazing, etc.

3400 Series are used for lower Cold Fractions (below 50%) and generate VERY cold air flow…as low as -50°F.  Some common applications for these are cryogenic lab sample cooling, circuit testing, or freeze seals in certain piping systems.

Temperature drops are dependent only on supply pressure and Cold Fraction setting. These values apply to any Vortex Tube, regardless of size/model.

Cold Fraction is adjusted by turning the Hot Air Exhaust Valve to let more, or less, hot air out, as shown in this short video:

What flow do I need?

Both the 3200 and 3400 Series Vortex Tubes are offered, from stock, in twelve distinct models of each series.  These are defined by the compressed air consumption, and the cold air flow is determined by the Cold Fraction setting.

Small Vortex Tubes come in three Models for each series, and consume 2, 4, or 8 SCFM when supplied with compressed air @100 psig.

Medium Vortex Tubes come in five Models for each series, and consume 10, 15, 25, 30, or 40 SCFM @100 psig.

Large Vortex Tubes come in four Models for each series, and consume 50, 75, 100, or 150 SCFM @100 psig.

Converting a Vortex Tube to a different Model (in the same size class) is as easy as changing the Generator (and the Taper Sleeve, for the Small Vortex Tubes):

The Generator and Taper Sleeve (*Small VT’s only) are changed by removing the Cold Cap.

So, for example, if you have a Model 3210 (10 SCFM consumption, 1,000 Btu/hr rated cooling) set to an 80% Cold Fraction, supplied with compressed air @100 psig & 70°F, it’s making a 16°F cold air flow of 8 SCFM.  If your situation calls for more flow, you can change the Generator…for example, if you convert it to a Model 3240 (40 SCFM, 2,800 Btu/hr rated cooling) – leaving the Cold Fraction at 80%, you’ll now get 32 SCFM of 16°F air.

What if you need colder air?  You can convert this same Medium Vortex Tube to a Model 3440 (40 SCFM consumption, max cold temperature) by changing the Generator again…and if you lower the Cold Fraction to 20%, it’ll make a -53°F cold flow of 8 SCFM.

Powerful and versatile, EXAIR Vortex Tubes are suitable for a wide range of applications requiring a consistent and reliable flow of cold air.  For help in selecting the right one for your needs, give me a call.

Russ Bowman
Application Engineer
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