EXAIR Vortex Tubes are for a Variety of Cooling Applications

Vortex tube
Cooling or Heating with the Vortex Tube

EXAIR Vortex Tubes are a low cost, reliable and maintenance free solution to a wide variety of industrial spot cooling problems.  They only requirement is a supply of compressed air as the power source.  Vortex Tubes have no moving parts and can produce temperatures that range from -50°F to +260°F (-46°C to +127°C).

Vortex Tubes produce two air streams one cold and one hot, the percentage of cold air flow from the inlet flow is referred to as the cold fraction.  The cold fraction is adjustable by the hot valve on the hot discharge side of the vortex tube.  Adjusting the hot valve results in both air temperature and air volume changes. The colder the air becomes, the volume of that cold air declines. So for very cold temperatures, a smaller volume of air is produced compared to a warmer air temperature.

For the vast majority of industrial cooling applications a larger volume of cool air will provide more efficient cooling than a lesser amount of very cold air.  Generally speaking the highest Btu/Hr values are in the 70-80% cold fraction range.

The exception to this would be in labs or special cases where the coldest temperatures are desired.  Adjusting a Vortex Tube is easy, simply insert a thermometer/thermocouple in the cold air exhaust and set the temperature by adjusting the valve on the hot end of the Vortex Tube.  You will know when you reach max refrigeration (80% cold fraction) as the cold air temperature will be 50°F (28°C) lower than the compressed air supply temperature.

EXAIR Vortex Tubes are constructed from stainless steel.  This ensures excellent wear resistance, corrosion resistance and assures years of reliable operation.  They are offered in 3 different size ranges (small, medium & large).  There are generators located inside the tube (user serviceable) that will change the volumetric flow.  The generators are available in a plastic construction or brass construction for high temperature applications.  The ranges 2 SCFM – 8 SCFM are designated as small Vortex Tubes, 10 SCFM – 40 SCFM are medium and 50 SCFM – 150 SCFM are large.  This feature allows you to customize or change your Vortex Tube for greater flexibility in a wide range of applications.

Vortex generator

Large Vortex Tubes are specified when a high flow of cold air is needed. There are 16 models to choose from in total.  Capable of providing 3,400 BTU/HR up to 10,200 BTU/HR of cooling power.  These have been used to cool high heat loads that are centrally located or to help cool samples of gases for testing.

Medium Vortex Tubes are the most popular – there are twenty to choose from, depending on the cold air flow rate and temperature you’re looking for. These can produce temperatures as cold as -40°F (-40°C) when set to a 20% Cold Fraction (which is the percentage of total supply air that’s directed to the cold end) and cold air flows as high as 32 SCFM when set to an 80% Cold Fraction, which will produce a cold air temperature of about 20°F (-7°C). Some common uses are cooling ultrasonic welds and brazed joints.

The Medium Vortex Tubes are so popular, in fact, that they’re incorporated into our Adjustable Spot Cooler and Cold Gun Systems. They come ready-to-go with mufflers, cold air hose kits, and magnetic bases, so they couldn’t be easier to use.

Adjustable Spot Cooler

Cold Gun Lineup

Small Vortex Tubes are great when low flows (less cooling power) will succeed, or if compressed air supply is limited.  There are 12 models in total to choose from. These are specified for much smaller applications, like cooling the needle of a sewing machine, small drill bits, etc. You can also get one with a cold air hose & magnetic base…that’s the Mini Cooler System.

Mini Cooler

If you would like to discuss Vortex Tubes, Spot Cooling, efficiency of your compressed air usage, quieter compressed air products and/or any EXAIR product,  I would enjoy hearing from you…give me a call.

Steve Harrison
Application Engineer
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Vortex Tubes Make Hot Air Too

Back in the spring, my good friend and co-worker Neal Raker wrote a great piece, titled “Can I Use A Vortex Tube For Heating?” which I will try my best not to borrow too much from or outright plagiarize in the blog to follow. I only mention it because I had the pleasure of helping a customer with one of the “usually few and far between” Vortex Tube heating applications recently.

Like Neal said, the conditions under which Vortex Tubes fit a heating application are fairly narrow, but certainly not unheard of. In this situation, a reciprocating air motor had been in place on a piece of factory machinery for years. A recent change in the part being manufactured meant that the motor had to be slowed down, which meant throttling down on the vent valve on the motor’s pneumatic exhaust. When they did this, the valve became prone to freezing up, meaning someone had to rig up a heat gun and climb up on top of the machine to the vent valve, directing hot air on the valve until it thawed. It got to be a real hindrance to the process when this happened several times a day.

The caller was familiar with our Vortex Tube products, having used Mini Coolers and Cold Guns in other parts of the plant. He knew that there was hot air coming out of the other end, and thought it could be used to thaw the vent valve, but was concerned, because it was such a low flow.

Mini Cooler (left) and Cold Gun (right).
Mini Cooler (left) and Cold Gun (right).  Cold air from one end; hot exhaust minimized on the other.

He was right: the hot air exhaust of both the Mini Cooler and Cold Gun is a small fraction of the total air supply…that’s by design. Also, it’s passed through a noise reducing muffler which further spreads it out to make it nice & quiet…also by design.

That’s when a fuller explanation of Vortex Tube operation came into play: See, the Mini Coolers and Cold Guns are all set to a high Cold Fraction (the percentage of supply air that is directed to the cold end,) so, although the hot exhaust is indeed fairly hot, there’s just not a lot of it. By contrast, our 3400 Series Maximum Cold Temperature Vortex Tubes are adjustable for lower Cold Fractions (from 20-50%,) meaning that the hot exhaust flow can range from 50-80% of the supply air flow. Additionally, the hot end of the Vortex Tube has male NPT threads, for convenient porting & direction of the hot air flow.

The EXAIR Vortex Tube.  Cold air from one end; hot air from the other.  Fully adjustable.
The EXAIR Vortex Tube. Cold air from one end; hot air from the other. Fully adjustable.

Now, back to the conditions that made this a good fit for the Vortex Tube: the machinery already had an ample and easily accessible supply of compressed air…they were able to tap a line from the air motor’s supply. The closest outlet for their heat gun was on the other side of the walkway, which meant they had to stretch an extension cord across the walkway, creating a trip hazard. The vent valve is also small enough that they could use a Model 3402 Vortex Tube, which utilizes only 2 SCFM @100psig…a tiny fraction of what the air motor uses.

With the Vortex Tube mounted permanently in place, the vent valve now operates flawlessly, without the need for manually thawing with the incredibly inconvenient heat gun.

If you think you might have a decent fit for a Vortex Tube heating application, give us a call. You may be right.

Russ Bowman
Application Engineer
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Vortex Tube Thaws Steam Connections on Bulk Liquid Sea Containers

Bulk container

Vortex Tube applications for cooling are many and a wide variety. Heating applications though, do tend to be a bit more elusive. That being said, I thought I would highlight a recent application where vortex tubes were used to thaw out steam lines that are used to heat up fluids in bulk sea containers.

We have all seen them running up and down the expressways, the large, bulk liquid containers that have the multi-modal capability to be on a ship, a train or a truck going down the road. I personally never thought about what the users of these tanks must do in order to get the liquid inside up to certain temperatures to allow the material inside to flow easily. I live in the Midwest area of the US, so we get really cold weather for only a few weeks during the year. In the Northern climates though, these bulk container users must have ways to thaw out the product before it can be used. To do this, these bulk containers are equipped with steam lines. Steam is used to heat the liquid inside to get it up to temperature. Once the steam is connected to the lines and circulating, all is well. But before they can get to that point, the steam connections on the tank are usually plugged with ice from condensate from previous use. The previous method was to simply snake a steam line up inside the heater lines to warm them up, but that presented a further problem. That same condensate ends up rolling out the pipe and dripping on the ground, re-freezing and creating a huge slip hazard.

 Steam connections

Above are the typical 1” BSP steam connections found on the bulk tanks.

In order to eliminate the slip hazard, the customer began looking for another method to supply a hot gas to these steam lines to thaw them out. In comes EXAIR with our Vortex Tube selection. The idea is to replace the mini steam line with the hot air output flow from a vortex tube to thaw out the connections. Since the customer has compressed air utility in plentiful supply on site, this makes for a very convenient way to warm up the pipes with a relatively “dry gas”. That being the dry compressed air supplied in the facility. The customer ended up using (2) model 3225 Vortex tubes with Cold Flow Mufflers, to provide the hot air for the steam connections. In fact, the diameter of the hot tube for the vortex tubes was the perfect size to simply slide up inside the steam pipes and hang there until the pipes were free of the problematic ice. There was still some small amount of liquid that re-froze from within the steam pipes, but it was certainly much more manageable than the mess the customer was dealing with previously.

Neal Raker, Application Engineer

Old Customer, New Problem, How Can we Help?

EXAIR has a special customer for whom we build vortex tubes to actually heat product up that is used in a rather cold and hostile environment. If the product being heated is not heated properly, the customer is unable to use it for the various lubrication needs they have in their remote location. Originally, the customer came to EXAIR because they felt their existing supplier was charging too much for their products and taking way too long for delivery. To make a long story short, I worked out the details of the vortex tube set-up based on the customer’s requirements and we produced a special cold muffler fitting that was the same as what had been produced by their previous supplier. We made a few tweaks to the design and ended up with a product that the customer was very happy with.

A little over two years later our customer came back to us with a complaint they had received from one of their end users and needed to know what we could do to advise them and help them out of the predicament they were in. After all, they didn’t really know and understand vortex tubes. When our customer came back to me recently, here is the issue that they put to me for consideration.

Their end use customer was using the vortex tube for the intended heating purpose. In fact, they had two of them. One was working very well and the other was not. The end user performed a bit of their own trouble-shooting and found that the material used in the special cold muffler would actually become clogged with ice and other debris from the compressed air that was coming through and also from splashing, rain and other sources of water from outside the heating device.

What happens to the hot end of a vortex tube when the cold end becomes plugged up and cannot flow freely? It forces more air out the hot end which actually has a cooling effect on the hot end. The temperature is no longer high enough to sustain the temperature needed and the end user is quite un-happy. The end user noted this and relayed the information back to our OEM client who, in-turn relayed back to me and asked for help.

My initial reaction when my OEM client asked about the problem was that in our standard products, we always use a “through hole” type muffler assembly on the cold end to keep it from becoming clogged in precisely the manner that the end customer had experienced with their unit. We had discussed this same issue early on with our client, but they were intent on keeping things the same as they always were. If it isn’t broken, don’t fix it was sort of the idea at the time.  With this understanding, I went back to our OEM client and suggested they try an arrangement that was more in line with our stock offering. There were a few advantages to it that our client needed to consider. 1. It would not freeze up and block the cold output flow thus causing problems with temperature on the hot end flow. 2. The proposed option was actually quite a bit less expensive than the custom option that the customer had originally specified. 3. By de-coupling the vortex tube muffler from the external housing, the customer has a lot more flexibility in where to actually locate the cold exhaust on their product. Before, they did not have this flexibility. Below is a quick mock-up photo of what I had proposed to our OEM client. I sent them these photos and their response was, “Great, please send us enough to outfit three vortex tubes so we can make a test.” We sent the parts over to them and so far the testing has shown a definite improvement in reliability of their product.

The point of the story is that we had a customer with a very definite idea of what they wanted initially, but when the time came when they needed help to get out of a tough situation, we were able to offer timely and reasonable advice to help our OEM client find their way through what could have been an otherwise very un-desirable situation.

Neal Raker
Application Engineer