FAQ

Vortex Tubes are a product of the EXAIR Corporation. They use compressed air as a power source, have no moving parts and produce cold air from one end and hot air from the other.

Usually the cold air is used for refrigeration or spot cooling applications. The hot air can be used for spot heating applications but the temperatures and volumes are not very high and usually there is a better way to get hot air.

No, for proper operation, the Vortex Tube cold outlet should not be subjected to any restrictions that would produce backpressure in excess of 5 PSIG. An Air Amplifier would restrict the flow of a Vortex Tube to the point where the backpressure is excessive and severely limit the cooling capacity of the Vortex Tube.

The Vortex Tube is a phenomenon of physics, no one knows exactly why a Vortex Tube works. A description of how the air moves is given below:

Compressed air, normally 80-100 PSIG (5.5 - 6.9 BAR), is injected tangentially through a generator into the vortex spin chamber. At up to 1,000,000 RPM, this air stream revolves toward the hot end where some escapes through the control valve. The remaining air, still spinning, is forced back through the center of this outer vortex. The inner stream gives off kinetic energy in the form of heat to the outer stream and exits the vortex tube as cold air. The outer stream exits the opposite end as hot air.

For more details, contact our Application Engineers at (800) 903-9247.

The Vortex Tube is the fundamental component inside all the applied EXAIR products that generate cold airflow. The Vortex Tube is available in 3 different sizes and produces a wide span of cooling capacities. All models shown in the catalog have an adjustable valve at the hot end that can change the proportions of hot and cold airflow to their respective ends. On special order, this valve can be replaced with a preset orifice that will provide a pre-determined amount of temperature drop/rise. The Vortex Tube also contains a series of inserts called “generators” that offer a wide range of flow rates for each Vortex Tube size. These generators size the flow to the application.

Most of the applied products (Cabinet Cooler, Cold Gun, Mini Cooler and Component Cooler) have a fixed total flow capacity that is ideal for that product. The valve has been replaced with a preset orifice that allows the Vortex Tube to deliver the highest cooling capacity available. The exception is the Adjustable Spot Cooler, where the temperature is adjustable and flow rates can be changed by using the interchangeable generators. All of these cold air products include other features that make them easy to mount and keep the noise level low.

The Vortex Tube Performance Charts give approximate temperature drops (and rises) from inlet air temperature produced by a Vortex Tube set at each cold fraction. Assuming no fluctuation of inlet temperature or pressure, a Vortex Tube will reliably maintain temperature within ±1°F.

There are a few reasons why this may be occurring.

• Check to see if the hot air exhaust is open, it is best to close it completely and back it out one full turn. The Vortex Tube is made to perform best when the hot air exhaust is not completely  closed.
• Check your inlet pressure. You must check the pressure right at the inlet of the Vortex Tube while it is operating. You will most likely need 80 to 100 PSIG for best performance.
• Check to see if your Vortex Tube is clean. You can do this by removing the cold cap and inspecting the parts for dirt, oil and other debris. Simply clean the parts and the inside of the tube as well as possible to regain your performance. Remember, the Vortex Tube needs clean, dry air to perform best.
• Make sure the cold cap or the cold muffler is tight.
• Reduce back pressure as much as possible. The performance of a Vortex Tube deteriorates with back pressure on the cold air exhaust. Pressure up to 2 PSIG will not change performance. 5 PSIG will change the cold air temperature approximately 5°F. If cold air ducting is used the total cross sectional area should be equal or greater than the area of the Vortex Tube cold air exhaust.
• Make sure you are checking the cold air temperature immediately inside the cold end exhaust, or use a pipe nipple attached to the cold end to prevent air entrainment in order to get a more accurate reading.

If you have any further questions, or if these tips failed to solve your problem, please contact an Application Engineer at 1-800-903-9247.

A Vortex Tube provides a temperature drop on the cold end and a temperature rise on the hot end from supply air temperature. Elevated inlet temperatures will produce a corresponding rise in both the cold and hot end air temperatures.

The performance of a Vortex Tube deteriorates with backpressure on the cold end exhaust. Low back pressure, up to 2 PSIG will not change performance. 5 PSIG will change performance by about 5°F.

There are several ways to determine the Cold Fraction you are currently using on your Vortex Tube.  One is to utilize the Performance Data chart in the Vortex Tube of section of our catalog or website which displays the temperature drop and rise of the Vortex Tube at different temperatures and supply pressures. You can measure the temperature of the cold air exiting the Vortex Tube and compare it to our charts. The air temp should be measured immediately out of the Vortex Tube as the air stream will warm as it mixes with ambient air.

The other method is to use an air flow meter to measure the volume of air both going into and out of the unit and comparing the hot or cold flow of the unit.  Comparing the hot or cold flow rate to the total will give you the relative cold or hot fraction setting.

Vortex Tubes are offered in three sizes with a variety of cooling capacities. Many common applications that incorporate Vortex Tubes are shown in the EXAIR Catalog and on our web site. If your particular application is not shown, but is similar to one of those described, it is best to order one of the EXAIR Cooling Kits. The Cooling Kits provide a Vortex Tube with all of the associated generators and accessories that allow you to experiment with various flows and temperatures. It is best to discuss your requirements with one of the EXAIR Application Engineers. They can help you select the size for your application.

Vortex Tubes are rated in Btu/hr. based on 100 PSIG inlet pressure at 68°F. Any deviation of pressure or temperature will affecting the rating of the Vortex Tube. Contact an Application Engineer to calculate the effects of temperature and/or pressure deviations on the Vortex Tube's rating.

The best way to confirm is to remove the hex cold cap and O-ring which holds the generator into the unit. Then, read the alphanumeric code on the flat surface of the generator. This will indentify many of the features of the Vortex Tube and if you have a stock Vortex Tube it will be all you need. If you have a Vortex Tube with special features, speaking with an Application Engineer will help determine what you have.

When you've obtained the alphanumeric code, you may contact EXAIR to obtain the corresponding model number.

Please contact us at 1-800-903-9247 or [email protected]

The Vortex Tube was invented quite by accident in 1928. George Ranque, a French physics student, was experimenting with a vortex-type pump he had developed when he noticed warm air exhausting from one end, and cold air from the other. Ranque soon forgot about his pump and started a small firm to exploit the commercial potential for this strange device that produced hot and cold air with no moving parts. However, the business soon failed and the Vortex Tube slipped into obscurity until 1945 when Rudolph Hilsch, a German physicist, published a widely read scientific paper on the device.

Much earlier, the great nineteenth century physicist, James Clerk Maxwell postulated that since heat involves the movement of molecules, we might someday be able to get hot and cold air from the same device with the help of a “friendly little demon” who would sort out and separate the hot and cold molecules of air.

Thus, the Vortex Tube has been variously known as the "Ranque Vortex Tube", the "Hilsch Tube", the "Ranque-Hilsch Tube", and "Maxwell’s Demon". By any name, it has in recent years gained acceptance as a simple, reliable and low cost answer to a wide variety of industrial spot cooling problems.

Yes, Cabinet Coolers are simply engineered Vortex Tubes for the specific purpose of cooling a cabinet. Vortex Tubes will perform the same as a Cabinet Cooler but there are distinct advantages to using the Cabinet Cooler for this application.

• Cabinet Coolers are available in models that are UL Listed to maintain the NEMA integrity of electrical panels. Vortex Tubes do not provide this level of protection.
• Cabinet Coolers have built in sound attenuation.
• Cabinet Coolers have a built in vent to allow warm panel air to escape from the cabinet.
• Cabinet Coolers are pre-set for maximum refrigeration and the setting cannot be changed. Vortex Tubes can be field adjusted, this leaves them susceptible to mis-adjustment and inefficient operation.

No, for proper operation, the Vortex Tube cold outlet should not be subjected to any restrictions that would produce backpressure in excess of 5 PSIG. An Air Knife would restrict the flow of a Vortex Tube to the point where the backpressure is excessive and severely limit the cooling capacity of the Vortex Tube. The design of the air knife is to entrain large amounts of ambient air and add it to the airstream reaching your parts. The dilution of 1 part of cold air mixed with 30-40 parts of ambient temperature air will result in air temperatures reaching your part to be not much different than ambient temperature.

No, for proper operation, the Vortex Tube cold outlet should not be subjected to any restrictions that would produce backpressure in excess of 5 PSIG. The hot end exhaust can withstand pressure up to 30 PSIG (depending on the cold fraction). If backpressure exceeds 5 PSIG, then the performance of the Vortex Tube will deteriorate. The hot end exhaust can withstand pressure up  to 30 PSIG (depending on the cold fraction).

An Air Amplifier or Air Knife would restrict the flow of a Vortex Tube to the point where the backpressure is excessive and severely limit the cooling capacity of the Vortex Tube.

If the goal were chilled airflow coming from an Air Amplifier or Air Knife, it would be unrealistic to expect a temperature decrease in the total output flow of either device with chilled compressed air. Compressed air will make up a small fraction of the total airflow output from these devices. The net temperature out will be a mix of compressed and ambient air with ambient air the majority of the volume. The net effect is that the airflow is going to be the same or very close to ambient temperature surrounding an Air Amplifier or Air Knife.

No, for proper operation, the Vortex Tube cold outlet should not be subjected to any restrictions that would produce backpressure in excess of 5 PSIG. A Super Air Wipe would restrict the flow of a Vortex Tube to the point where the backpressure is excessive and severely limit the cooling capacity of the Vortex Tube.