Tag: freeze seal

How to Apply Vortex Tubes and Understand Cold Fractions

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It’s been almost 100 years since Georges Ranque discovered the vortex tube phenomenon. Since then, they’ve become one of the best worst kept secrets in industry…I talk to callers all the time who have a piece of equipment that came with one of our Cabinet Cooler Systems installed, and they want to know how to get cold air like that for a machine tool cutting or spot cooling application. Other callers have discovered Vortex Tubes for the first time via a web search, or they saw one at a customer’s (or vendor’s) facility. They often sound like someone asking a magician to reveal the secret behind a trick. Of course, it’s not magic (not really) – but it is certainly a neat trick:

Then, the discussion turns to product selection. EXAIR Vortex Tubes come in three sizes, with multiple Models in each size range. Those different Models are all the same Small, Medium, or Large Vortex Tube, with a different Generator installed, which determines the amount of compressed air the Vortex Tube will consume…and the Cold Fraction range. These two variables go hand in hand when determining which Vortex Tube is right for the application.

‘Cold Fraction’ is the term for the percentage of the supply air that’s directed to the cold end. The higher the Cold Fraction, the higher the flow, and the temperature, of the cold air flow. Conversely, the lower the Cold Fraction, the lower the cold air flow…and temperature.

For jobs that call for rapid cooling to ambient temperature (or a little below), a “Max Refrigeration” Generator is installed in a 3200 Series Vortex Tube. They are designed to direct most of the compressed air flow to the cold end, exhausting a smaller amount out of the hot end. A Vortex Tube set at an 80% Cold Fraction is generally very close to being optimized for these applications: they’re putting out a decent amount of air flow, with a 54F temperature drop. Assuming the compressed air supply is roughly room temperature, that means you’re blowing 20 to 30F (-6.6 to -1.1C) air onto your part. Most of the time, it’ll cool it down in a real hurry. The final piece of the puzzle, then, is determining the cold air flow rate. Our lowest capacity Small Vortex Tube with a Max Refrigeration Generator will use 2 SCFM @100psig, and generates a flow of 1.6 SCFM of cold air. On the other end of the spectrum, our highest capacity Large Vortex Tube uses 150 SCFM @100psig, and gives you a cold flow of 120 SCFM. There are ten Models in between, so we can come quite close to an optimal selection for just about any size/shape of part that needs cooled.

Keep in mind that there are two variables in a convection/conduction air cooling application: the flow rate of the air, and the difference in temperature in the cooling air and the hot part. We’ll always recommend starting at the highest cold fraction, but you may find that a little bit lower flow…and the lower temperature that comes with it…might suit your needs better. Good news is, that doesn’t change the compressed air consumption, so you can optimize performance at no additional cost of operation.

Other applications call for air that’s just as cold as possible. For those, we offer our 3400 Series “Max Cold Temperature” Vortex Tubes. Where the 3200 Series’ Cold Fractions are adjustable from 50-80%, the 3400 Series can be adjusted from 20-50%. Assuming, again, that the compressed air supply is roughly room temperature, at a 20% Cold Fraction and 100psig supply pressure, your cold flow can be as low as -50F (-45.6C). If you’re trying to get something to a particularly low temperature – lab samples or circuits that need to be tested at a certain temperature, or freeze seals in piping systems, for instance – then a 3400 Series Vortex Tube is just what you’re looking for. These come in the same sizes & Models as the 3200 Series, from 2 to 150 SCFM.

Another nice thing about using a Vortex Tube for cold air is that you can turn them on and off as frequently (or as seldom) as needed. They’re generating cold air flow, at their published rated temperature, instantly. There are no moving parts to wear, so you can cycle them on and off rapidly, or let them run continuously. In fact, if you supply them with clean, moisture free air, they’ll run darn near indefinitely, maintenance free.

Here’s a short video, showing how to adjust the Cold Fraction of a Vortex Tube. If you’d like to find out more, give me a call.

Russ Bowman, CCASS

Application Engineer
EXAIR Corporation
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When Efficiency And Practicality Collide

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Even if you’re a casual reader of our blogs, you already know that EXAIR Application Engineers LOVE to preach efficiency in the use of compressed air…it’s our “bread and butter;” the very nature of our business. This year, we’re celebrating thirty-five years of leading the way in the development of efficient, safe, and quiet compressed air products. Our track record of success as a solutions provider across a diverse range of industrial and commercial applications is well documented in our blogs, as well as Knowledge Base and Case Study Libraries.  We devote considerable resources (engineering, research & development, product testing, etc.) to making certain that EXAIR Intelligent Compressed Air Products cost less to operate, and perform better, than whatever you’re using right now.

Strange as it may seem, though, sometimes our products are EXTREMELY popular in cases where they INCREASE a facility’s consumption of compressed air…by replacing something that DOESN’T use compressed air at all:

*I’ve written before about how our Large Maximum Cold Temperature Vortex Tubes have replaced liquid nitrogen rigs in freeze sealing operations.  Now, a Vortex Tube directs a portion of its air supply to (usually) unusable hot exhaust, in order to generate the usable flow of cold air.  When compared to the costs of liquid nitrogen and the resources involved to get it where it needs to be, though, the cost of the compressed air needed to operate the Vortex Tube is indeed the practical solution.

A 1/4 ton of refrigeration from a product that fits in the palm of your hand, and all you need is a supply or compressed air!

*Line Vacs are probably THE prime example of the value of using compressed air where it wasn’t used before…replacing a “bucket and ladder” operation:

Straight from our Catalog, a perfect example of using valuable compressed air to save even more valuable resources.

*Then there are the situations that just come down to time.  In large spaces, our Super Blast Safety Air Guns can be used to “sweep” the floor in a fraction of the time it takes an operator with a push broom.

Super Blast Safety Air Gun makes short work of large area cleanup.

To make a long story just a little bit longer…if you’re using compressed air, you can use it better with EXAIR’s engineered compressed air products.  And there are plenty of practical applications where you’re not using compressed air right now too.  If you’d like to find out more about either one, give me a call.

Russ Bowman
Application Engineer
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Cool Job, Cool Products

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I’ve got a pretty cool job. I’ve written about this before…in fact, as recently as last week, in a piece about workplace safety, and how EXAIR is all over it, all the way. Brian Farno also blogged the other day about how EXAIR recognizes, appreciates, and celebrates achievement. Like usual, actually.

So yeah; this is a pretty cool job. And, just to put that into perspective, my first “grown up” job set the bar pretty high: upon completion of Naval Nuclear Power School, I was assigned to the initial manning crew of a new construction Trident submarine. When I got there in the spring of 1987, “tha thirty-five boat,” as the future USS Pennsylvania (SSBN-735) was known, was ON the pier (not NEXT to it) and we boarded through hull cuts in Engine Room Lower Level & the Torpedo Room. For two years, we worked with shipyard personnel to install, test, & certify all ship’s systems, and then took her out in the summer of 1989 for a rigorous series of sea trials. I wish there were words capable of conveying the extent of “job satisfaction” we felt when we submerged for the first time, and the whole ocean stayed outside the boat.

I was reminded of this the other day when I saw a news account of the bow section of a submarine being transported via barge from the shipyard that fabricated this section, to the shipyard that’s assembling the boat. Here’s a video clip of one such transit, from about a year ago:

I’ve written before about how compressed air is (and isn’t) used on board a submarine at sea. Compressed air is also used, for some pretty neat stuff, in their construction & service. And EXAIR Compressed Air Products are in the mix:

*Sometimes during work on a piping system, it’s not possible to isolate a particular section with valves, so a freeze seal is applied: a collar fits around the outside of the pipe, and very cold fluid is circulated through the collar. This freezes the liquid inside the pipe, forming a “plug,” which allows you to work on the piping downstream, just the same as if you had shut a valve there. One method of doing this is with liquid nitrogen…you take a big tank of the stuff to your work site, implement all the safety precautions you need to handle pressurized liquid at -321°F (spoiler alert: it’s complicated,) make up your connections, hope they don’t leak, and activate the system. Depending on the length of the job and the size of the tank, you may need to change it out…which, again, is complicated.  And yes, I’ve done it.

It's a real shame to foul this view with a block & tackle to lower a pressurized nitrogen tank down.
It’s a real shame to foul this view with a block & tackle to lower a pressurized nitrogen tank down.

Or, like several shipyards are doing currently, you can install an EXAIR Maximum Cold Temperature Vortex Tube to the collar, run a compressed air line to it, and you can supply cold air as low as -40°F, which will freeze a plug in that pipe for as long as you keep your air compressor running.

Vortex Tube
EXAIR Vortex Tubes produce cold air, on demand, with no moving parts.

*Another application has to do not with the equipment, but the people working on it. Welding is a hot job – there’s really no way around it – and welding in tight spaces can present real issues for the folks involved. Fans and blowers can provide a good amount of ventilation, but they also take up some room, which there may not be any to spare.

Enter EXAIR Air Amplifiers – they’re compact, lightweight, and use a small amount of compressed air to blow a high flow of cooling air, right where it’s needed.

EXAIR Air Amplifiers use a small amount of compressed air to create a tremendous amount of air flow.
EXAIR Air Amplifiers use a small amount of compressed air to create a tremendous amount of air flow.

These are just a couple of examples of how a large industry – shipbuilding – is using EXAIR products to capitalize on efficiency in a challenging environment. Regardless of your situation, if you’d like to learn if EXAIR can help out, give us a call.

Russ Bowman
Application Engineer
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Up Ladder courtesy of Russ Bowman  Creative Commons License