A manufacturer of automotive power transmission shafts was experiencing frequent failure of high pressure plastic rollers on their spin tester. There are four rollers in a 90° array that center the shaft during spin testing. They exert a pressure of around 1,500psi onto the shaft while it’s rotating at 1,000rpm. This generates enough heat to actually melt the rubber coating on rollers, which means stopping testing (which holds up production) while they change out the rollers. Just for it to start all over again.
Thing was, they wanted to mount the Adjustable Spot Coolers where they could have access to the Temperature Control Valve, but the cold air Hose Kit wouldn’t reach the shaft. So they got a couple of extra sections of the cold air hose…they needed one section of the ‘main’ (shown circled in blue, below) to reach into the test rig’s shroud, and two sections of the ‘branch’ (circled in green) to reach to each roller.
Now, adding too much hose length will start to put line loss on the cold air flow, and it will pick up heat from the environment. But if you just need that extra foot of hose to get the job done, this generally works just fine. The extra foot or so they’ve added (5″ to the main and 6″ to each branch) has solved their problem…they haven’t had to replace a roller since the Adjustable Spot Cooler Systems were installed.
By using only a source of compressed air, theCold Gun and High Power Cold Gun produces a stream of clean, cold air 50°F (28°C) below your compressed air supply temperature. The Cold Gun is very quiet at only 70 dBA and has no moving parts to wear out. Just supply it with clean compressed air and it’s maintenance free.
How does it work, and what are the benefits?
The Cold Gun uses compressed air to produce a stream of clean, cold air at 50°F (28°C) below supply air temperature. Generally this will be 20°F-30°F outlet temperature.
They use Vortex Tubetechnology…no moving parts to wear out.
Instant cold air flow with no moving parts!
Cold flow and temperature are preset to optimize cooling capability, and are non-adjustable to prevent freeze-up during use.
Eliminates the expense of both the purchase & disposal of cutting fluids when replacing expensive mist systems.
Removes the potential for health problems associated with breathing mist & vapors, and the safety issue of slipping on a wet floor.
Cold Gun Aircoolant System selection is easy & straightforward…we offer a standard, and a High Powerversion to meet your specific needs.
We also offer Single & Dual Point Hose Kits, to further meet the needs of your application.
One of the best applications I have seen with our cold gun came from a customer in Peru. They are a gold mining operation and they were having trouble with the liquid they were using to cool a saw. Read all about it here!
If you have an application that you believe would be better served by the use of an EXAIR Cold Gun, give us a call.
The Vortex Tube is a low cost, reliable, maintenance free way to provide cooling to a wide variety of industrial spot cooling problems.
There are two (2) popular uses for the Vortex Tubes. One is to spot cool a warm item as fast as possible. The other is to chill an item to as low a temperature as possible. Because these are very different requirements, different Vortex Tube configurations exist to handle each.
For those applications of spot cooling, we recommend the 3200 series of Vortex Tubes. They are designed to be most efficient at providing maximum refrigeration, which is a function of high cold air flow rate and moderate temperature differential of the cold air to the warm item.
And for those applications of chilling an item to a very low temperature at low flow rate , we recommend the 3400 series of Vortex Tubes. They are designed to be most efficient at providing maximum cold air temperatures, but with a lower cold air flow rate.
An important parameter for the Vortex Tubes is the Cold Fraction. By adjusting the hot valve on a vortex tube, the amount of air that is discharged through the cold end changes. When expressed as a percentage of the total compressed air that is supplied to the vortex tube, we get the Cold Fraction. For example, if the hot valve is adjusted so that for every 10 parts of compressed air supplied, we get 7 parts of cold air, then we have a 70% Cold Fraction. When you know the Cold fraction setting and the compressed air supply pressure, you can use the Vortex Tube Performance tables and get the cold air discharge temperature.
Using the table below left, at 100 PSIG compressed air pressure and a 70% Cold Fraction, we can expect the cold air discharge temperature drop to be 71°F. With 70 ° compressed air temperature, the cold air will be at -1°F.
The 3200 series of Vortex Tubes are for use in the 50-80% Cold Fraction range, and the model 3400 series is designed for use in the 20-50% Cold Fraction ranges, to maximize the performance of each.
In summary, the selection of the Vortex Tube that best meets the application needs is based on the desired cold air flow rate, and the temperature of air desired. Once these are known, using the tables can provide the information needed to select the best option.
For those applications where we are unsure what will work best, we offer the EXAIR Cooling Kits, that include a Vortex Tube (small, medium, or large) and an array of Generators, to allow the configuration of the full range of Vortex Tubes within each size family.
Model 3908 – Small Vortex Tube Cooling Kit – build models 3202, 3204, 3208, and 3402, 3404, 3408
Model 3930 – Medium Vortex Tube Cooling Kit – build models 3210, 3215, 3225, 3230, 3240, and 3410, 3415, 3425, 3430, 3440
Model 3998 – Large Vortex Tube Cooling Kit – build models 3250, 3275, 3298, 3299, and models 3450, 3475, 3498, 3499
If you have questions about Vortex Tubes or any of the 16 different EXAIR Intelligent Compressed Air® Product lines, feel free to contact EXAIR and myself or any of our Application Engineers can help you determine the best solution.
The Adjustable Spot Cooler is a low cost, reliable , maintenance free way to provide spot cooling to a myriad of industrial applications. Simply turn the knob, and the temperature can be changed to suit the needs of the process. The Adjustable Spot Cooler delivers precise temperature settings from -30°F (-34°C) to room temperature.
It can produce temperatures form -30°F to +70°F (-34°C tp +21°C)
Parts included for flow rates of 15, 25 and 30 SCFM (425, 708, 850 SLPM.) The unit comes from the factory set at 25 SCFM (708 SLPM)
It can produce refrigeration up to 2,000 BTU/hr (504 Kcal/hr.)
A swivel magnetic base allows for easy mounting and portability, you can move it from machine to machine as needed. The flexible cold air outlet tubing holds its position and is easy to aim. Most importantly, there are no moving parts or CFC’s, ensuring maintenance free operation.
The Adjustable Spot Cooler incorporates a vortex tube to convert a supply of compressed air (1) into two low pressure streams, one hot and one cold. With the turn of a knob, the temperature control valve (2) allows some hot air to flow through a muffling sleeve and out the hot air exhaust (3). The opposite end provides a cold air stream (4) that is muffled and discharged through the flexible hose, which directs it to the point of use. The swivel magnetic base (5) provides easy mounting and portability.
The Adjustable Spot Cooler can produce a wide range of air flows and temperatures as determined by the temperature control valve knob setting and the generator installed. The generator controls the total SCFM (SLPM) of compressed air consumption, and is easy to change. From the factory, the 25 SCFM (708 SLPM) generator is installed, producing up to 1,700 BTU/hr (429 Kcal/hr) of cooling. For less cooling, the 15 SCFM (425 SLPM) generator can be installed, providing up to 1,000 BTU/hr (252 Kcal/hr) of cooling. And for more cooling, the 30 SCFM (850 SLPM) generator can be installed, providing up to 2,000 BTU/hr (504 Kcal/hr) of cooling.
Two (2) Systems are available as shown below, and include the 15 and 30 SCFM (425 and 850 SLPM) generators, a filter separator, and either a single or dual point hose kit.
Adjustable Spot Cooler Systems
If you have questions about the Adjustable Spot Cooler or any of the 16 different EXAIR Intelligent Compressed Air® Product lines, feel free to contact EXAIR and myself or any of our Application Engineers can help you determine the best solution.
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).
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.
If you’ve got any other specific requirements – special materials, fittings, custom flow/temperature parameters, etc., give me a call; let’s talk.
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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).
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)
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.
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.
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.
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.
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.