Max Refrigeration vs. Max Cold Temp Vortex Tubes

Here at EXAIR, our vortex tubes are offered in two separate series. The reason for this is to optimize the performance of the cold air temperature drop when operating with opposite ends of the cold fraction chart. The maximum refrigeration vortex tubes, 32xx series, perform optimally when they are set to a greater than 50% cold fraction.  The maximum cold temp vortex tubes, 34xx series, perform optimally when they are set to a less than or equal to 50% cold fraction. The cold fraction is discussed more in-depth within this link from Russ Bowman, Vortex Tube Cold Fractions Explained. This blog is going to explain a little further why one series of vortex tubes would be chosen for an application over another.

Cold Fraction
EXAIR Vortex Tube Performance Chart

Maximum refrigeration (32xx) vortex tubes are the most commonly discussed of the two types when discussing the optimal selection of the vortex tube for an application. The 32xx series vortex tubes achieve a maximum refrigeration output when operated at 100 psig inlet pressure with around  80% cold fraction. This would give a temperature drop from incoming compressed air temperature of 54°F (30°C). The volumetric flow rate of cold air will be 80% of the input flow which means only 20% is being exhausted as warm exhaust air. By keeping the flow rate higher the air is able to cool a higher heat load and is the reason the vortex tube is given a BTU/hr cooling capacity.

Vortex Tube Hot Valve Adjustment

Maximum cold temperature (34xx) tubes are less common as their applications are a little more niche and require a very pinpoint application. Rather than changing the temperature inside of a cooling tunnel or cooling an ultrasonic welding horn, the max cold temp vortex tube is going to have a minimum cold flow rate, less than 50% of input volumetric flow.  This minimal flow will be at temperature drops up to 129°F (71.1°C) from the incoming compressed air temperature.  This air is very cold and at a low flow. A 20% cold fraction exhausts 80% of the input volume as hot air. This type of volume would be ideal for sensor cooling, pinpoint cooling of a slow-moving operation, or thermal testing of small parts.

In the end, EXAIR vortex tubes perform their task of providing cold or hot air without using any refrigerants or moving parts. To learn more about how they work, check out this blog from Russ Bowman. If you want to see how to change the cold fraction, check out the video below. If you would like to discuss anything compressed air related, contact an application engineer, we are always here to help.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

 

Adjustable Spot Cooler Removes Tackiness from Plastic Tubes

Black PVC Tube

A manufacturing plant contacted EXAIR to help them with a “sticky” situation.  This company extruded PVC tubes that would be used as fuel lines on small engines.  Plasticizers are typically used to add flexibility to plastic materials.  For the PVC material above, a plasticizer was added to make it softer and more elastic.  The issue that they saw was the outer surface of the tubes were tacky from the plasticizer and heat which made it difficult to handle in packaging the tubes.

This company extruded many different diameters, but they wanted to target their most difficult size, the smallest tube.  The dimensions were given as 0.187″ (4.7mm) O.D. by .0934″ (2.4mm) I.D., and the feed rate was close to 4 feet/min (1.2 meter/min).  The problem area that they explained was at the end of the production line where the extruded tubes were cut by a blade cutter into 12” (305mm) lengths.  The tubes would then fall into a collection bin for batch processing.  Since the collection bin was setup at a slight upward angle, they wanted the tubes to gather toward one end of the bin.  Since the tubes were still hot and sticking to each other, the operators had to individually handle each tube which was counterproductive and time-consuming.  After our discussions, I suggested that cold air could harden the PVC tube enough by removing heat and help to “set”  the platicizer.  Since they manufactured different sizes and feed rates, we needed to have adjustability as well in our cold air device.

How the Adjustable Spot Cooler Works

One of our most versatile spot cooling instruments is the EXAIR Adjustable Spot Cooler.  This system uses the Vortex Tube technology to convert compressed air into a cold air stream without any moving parts, refrigerants, or motors.  The Adjustable Spot Cooler is a low-cost, reliable, maintenance-free way to give spot cooling for a myriad of industrial applications.  For this customer, this product gave them the versatility that they were needing.

EXAIR stocks these units with either a single or dual point hose kit, a magnetic base, a filter separator, and two additional generators.  The control valve at the end of the unit adjusts the output temperature down to -30 oF (-34 oC) with a turn of a knob.  The generators are specifically engineered to control the amount of compressed air that is used.  Both types of controls will allow this customer to “dial in” the correct cooling capacity for the operation.  The filter separator included with the system will clean the compressed air to keep the unit and the product free of dirt and debris.  The magnetic base which this customer really liked makes the Adjustable Spot Cooler portable for use in different areas.

3925 Adjustable Spot Cooler

I recommended the model 3925 Adjustable Spot Cooler because it had the dual point hose kit to blow cold air on both sides of the tubes.  Since this company had different tube diameters and thicknesses, adjustability was very critical.  If the tubes got too cold, cracks could occur from the blade cutting machine; and, if the tubes were too warm, the tackiness on the surface of the tube would remain.   Once they installed the Adjustable Spot Cooler, this company was able to increase their packaging line for the different size PVC tubes.  Now the operators could reach into the collection bin and grab many aligned tubes instead of individually separating and sorting.

If you have a “sticky” situation, the EXAIR Adjustable Spot Cooler may be a product for you.  The company above was able to have their tubes slide together in the collection bin.  Many applications could be improved by adding cold air.  And, if you have a similar situation, an Application Engineer at EXAIR will be happy to discuss a solution.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

 

Photo: Black tube by NIMR LondonCC License 2.0

Cold Gun Aircoolant System™: Overview

EXAIR Cold Gun Promotion

Many machining companies like to use coolant to flood their parts for drilling and milling operations.  But what if there was an alternative way?  EXAIR has an interesting technique by using cold air instead of coolant.  This would help save time by eliminating cleaning and drying of parts as well as reducing coolant waste.  EXAIR calls this product our Cold Gun Aircoolant System™.

How the Cold Gun Works

The Cold Gun Aircoolant System uses a Vortex Tube to produce a cold air stream at 50oF (28oC) below supply air temperature.  Heat is one of the major causes for dulling and premature failures for tools, and by blowing cold air, it will reduce the heat buildup in tools while also removing the chips from the surface.  The EXAIR Cold Guns are very compact, portable, and easy to use.  Just attach compressed air to the unit, and it will produce cold air.  Since they do not have any moving parts, Freon, or electricity to operate, it is maintenance-free and long-lasting.  And, EXAIR offers a 5 year “Built To Last” warranty against defects in workmanship and materials.  These systems will extend tool life, improve tolerance control, and increase production rates by replacing coolant during milling, cutting, and drilling operations.

The benefits of using the Cold Gun Aircoolant System extends beyond reducing tool wear, finishing with dry parts, and surface smearing.  It can be used in applications where liquid coolant cannot be used.  This would include wood products, MDF, and plastics.  As insulators, cutting tools will get extremely hot as the material will not remove any heat like with metal chips.  Thus, machining can soften, gall, or burn the surface of the material; allowing only slow speeds for operations.  The cold air from the Cold Gun can keep the tools sharp and the materials hard and firm.  With plastic materials, this is very beneficial as it will keep the plastic rigid for tight tolerance machining.  If burnishing or scoring is occurring, the Cold Gun Aircoolant Systems can help to improve the surface finish of your product.  Other applications would include surface grinders, laser cutters, hot melt setting, and band saws.  The Cold Gun Aircoolant Systems are a low-cost solution that can do a lot of great things to improve processes.

Cold Gun Aircoolant Systems

EXAIR offers two types, the Cold Gun and the High Power Cold Gun.  The High Power Cold Gun blows twice the amount of cold air as the Cold Gun which doubles the cooling capacity.  They come standard with either a Single Point or a Dual Point Hose Kit with a cone and flat nozzle.  All systems come with a magnetic base and a filter separator.  The magnetic base makes this device simple to attach to your machine and start using.  The four models that EXAIR stocks are in the photo above.

EXAIR is running a promotional offer on the Cold Gun Aircoolant Systems.  From now until the end of yr2019; if you buy a Single Point Cold Gun System or a Single Point High Power Cold Gun System; model W5215 and model W5230 respectively, we will include a free model 5902 Dual Point Hose Kit, a $39.00 value, with your system.  And as always, EXAIR offers a 30-day unconditional guarantee for our customers in the U.S. and Canada to try them out.  If you have an application that you believe would be better served with an EXAIR Cold Gun Aircoolant System™, contact an Application Engineer.  And take advantage of our promotional offering by receiving a FREE Dual Point Hose Kit.

 

John Ball
Application Engineer

Email: johnball@exair.com
Twitter: @EXAIR_jb

Promos, Freebies, and Some Amazing Products

Like many companies, here at EXAIR we generally always have a promotional offering.  These rotate throughout the months and this month is no different.  The current offering involves the EXAIR Cold Gun Aircoolant Systems.

These systems help to reduce cutting fluid use, increase production speeds, increase tool life, and has helped more customers than I know.  One customer in particular is a maintenance worker from a welded tube manufacturer.  This facility had very little amount of downtime permitted due to the high efficiency and high volume of orders.  When a machine went down the maintenance team were in like a trauma team to determine the cause of failure and get it remedied to get the line back up and running. One of the biggest problems they would have is when they would have to dry machine a quick part to get the machine back up and running, this would either ruin tools or they would have to slow down the machining time to get the surface finish and dimensions they truly needed.  After talking with us the team ordered a Single Point Cold Gun Aircoolant System as these parts were generally smaller shafts or machine dogs.

They received the system in and sure enough a machine went down.  The crew went to work and once the part needed was found they got to work on their lathe trying to make a new piece.  The Cold Gun held itself straight to the headstock thanks to the integrated magnet and the flexible single point hose kit routed the cold air straight to the cutting point.  They didn’t have to fill up the liquid tank or setup the mist system on the lathe, they simply turned on the compressed air and let the lathe do the work.  They were able to take what had recently been around a three hour machine job with heavy wear on tooling to a two hour job, no finish pass was needed on the part, and their tools weren’t completely spent by the end of the job.

They got the part back into the machine, made adjustments, and then went to work getting the machine back into production.

Right now, if you would like to try out a Cold Gun Aircoolant System you can order before 12/31/2019 and use the link to order through our promotion in order to receive a free Dual Point Hose Kit with your qualified purchase.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

Vortex Tube Cold Fractions Explained

Simply put, a Vortex Tube’s Cold Fraction is the percentage of its supply air that gets directed to the cold end. The rest of the supply air goes out the hot end. Here’s how it works:

The Control Valve is operated by a flat head screwdriver.

No matter what the Cold Fraction is set to, the air coming out the cold end will be lower in temperature, and the air exiting the hot end will be higher in temperature, than the compressed air supply.  The Cold Fraction is set by the position of the Control Valve.    Opening the Control Valve (turning counterclockwise, see blue arrow on photo to right) lowers the Cold Fraction, resulting in lower flow – and a large temperature drop – in the cold air discharge.  Closing the Control Valve (turning clockwise, see red arrow) increases the cold air flow, but results in a smaller temperature drop.  This adjustability is key to the Vortex Tube’s versatility.  Some applications call for higher flows; others call for very low temperatures…more on that in a minute, though.

The Cold Fraction can be set as low as 20% – meaning a small amount (20% to be exact) of the supply air is directed to the cold end, with a large temperature drop.  Conversely, you can set it as high as 80% – meaning most of the supply air goes to the cold end, but the temperature drop isn’t as high.  Our 3400 Series Vortex Tubes are for 20-50% Cold Fractions, and the 3200 Series are for 50-80% Cold Fractions.  Both extremes, and all points in between, are used, depending on the nature of the applications.  Here are some examples:

EXAIR 3400 Series Vortex Tubes, for air as low as -50°F.

A candy maker needed to cool chocolate that had been poured into small molds to make bite-sized, fun-shaped, confections.  Keeping the air flow low was critical…they wanted a nice, smooth surface, not rippled by a blast of air.  A pair of Model 3408 Small Vortex Tubes set to a 40% Cold Fraction produce a 3.2 SCFM cold flow (feels a lot like when you blow on a spoonful of hot soup to cool it down) that’s 110°F colder than the compressed air supply…or about -30°F.  It doesn’t disturb the surface, but cools & sets it in a hurry.  They could turn the Cold Fraction down all the way to 20%, for a cold flow of only 1.6 SCFM (just a whisper, really,) but with a 123°F temperature drop.

Welding and brazing are examples of applications where higher flows are advantageous.  The lower temperature drop doesn’t make all that much difference…turns out, when you’re blowing air onto metal that’s been recently melted, it doesn’t seem to matter much if the air is 20°F or -20°F, as long as there’s a LOT of it.  Our Medium Vortex Tubes are especially popular for this.  An ultrasonic weld that seals the end of a toothpaste tube, for example, is done with a Model 3215 set to an 80% Cold Fraction (12 SCFM of cold flow with a 54°F drop,) while brazing copper pipe fittings needs the higher flow of a Model 3230: the same 80% cold fraction makes 24 SCFM cold flow, with the same 54°F temperature drop.

Regardless of which model you choose, the temperature drop of the cold air flow is determined by only two factors: Cold Fraction setting, and compressed air supply pressure.  If you were wondering where I got all the figures above, they’re all from the Specification & Performance charts published in our catalog:

3200 Series are for max cooling (50-80% Cold Fractions;) 3400’s are for max cold temperature (20-50% Cold Fractions.)
Chocolate cooling in brown; welding/brazing in blue.

EXAIR Vortex Tubes & Spot Cooling Products are a quick & easy way to supply a reliable, controllable flow of cold air, on demand.  If you’d like to find out more, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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Adjustable Spot Cooler Keeps Rollers Rolling

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.

This, of course, was an ideal application for a Vortex Tube cooling solution.  They wanted to aim the cold air flow from the dual points of two Model 3925 Adjustable Spot Cooler Systems at four points of the shaft, right where it starts to contact the rollers.

Model 3925 Adjustable Spot Cooler System has a Dual Outlet Hose Kit for distribution of cold air flow to two points.

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.

If you need a little extra reach from an Adjustable Spot Cooler or a Cold Gun, the cold air hose segments snap together, and apart, for any length you need.

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.

If you’d like to find out more about how EXAIR Vortex Tubes & Spot Cooling Products can prevent heat damage in your operation, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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Generators for the EXAIR Vortex Tubes

Vortex generator

The EXAIR Vortex Tubes use compressed air to generate cold air down to -50 deg. F (-46 deg. C) without any moving parts, freon, or electricity.  By design, it will produce hot air at one end and cold air at the other.  EXAIR offers different cooling capacities ranging from 135 BTU/hr (34 Kcal/hr) to 10,200 BTU/hr (2,570 Kcal/hr).  This cooling phenomenon begins by spinning the air at a high rate of speed inside the Vortex Tube.  The “separation” of temperatures starts at the generator.  In this blog, I will discuss the features of the generator and how our design allows for an efficient way to cool and heat the air flows.

Vortex Family

EXAIR stocks three different sizes of the Vortex Tubes; small, medium, and large.  Each Vortex Tube will use a generator to define the cooling capacity and compressed air usage.  When compressed air enters the Vortex Tube, it will have to pass through the generator first.  The generators are engineered with vane openings to initiate the spinning of the air and to control the amount of air that can pass through it.  As an example, for a medium-sized Vortex Tube, a model 10-R generator will only allow 10 SCFM (283 SLPM) of air at 100 PSIG (6.9 Bar).  While in that same size body, a model 40-R generator will allow 40 SCFM (1,133 SLPM) of air at 100 PSIG (6.9 Bar) to be used.  Precision in the design of the generators is what sets EXAIR apart with efficiency and effectiveness in cooling.

EXAIR Vortex Tube Performance Chart

EXAIR created a chart to show the temperature drop for the cold end and temperature rise for the hot end, relative to the incoming compressed air temperature.  Across the top of the chart, we have Cold Fraction and along the side, we have the inlet air pressure.  The Cold Fraction is the percentage of the inlet air that will blow out the cold end of the Vortex Tube.  This is adjustable with a Hot Exhaust Air Valve at the hot end.

As you can see from the chart, the temperature difference changes as the Cold Fraction and inlet air pressure changes.  You may notice that it is independent of the size of the generator.  So, no matter which size Vortex Tube or generator is used, the temperature drop and rise will follow the chart above.  But just remember, cooling capacity is different than cooling temperature.  At the same settings, a larger generator will give you more mass of air to cool faster.

Now, let’s look inside the Vortex Tube (reference photo above).  As the compressed air passes through the generator, the change in pressure will create a powerful vortex.  This spinning vortex 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 hot air that leaves the Vortex Tube.  The remaining part of the air is redirected toward the opposite end as the cold flow, or Cold Fraction.

Now, what separates EXAIR Vortex Tubes from our competitors are the three different styles of generators and two different materials for each size.  These generators are engineered to optimize the compressed air usage across the entire Cold Fraction chart above.  With temperatures above 125 oF (52 oC), EXAIR offers a brass generator for the Vortex Tubes.  The same precision design is applied but for higher ambient temperatures.  With the wide range of Vortex Tubes and generators, we can tackle many types of cooling applications.

If you would like to discuss your cooling requirement with an Application Engineer at EXAIR, we will be happy to help.  This unique phenomenon to generate cold air with no moving, freon, or electricity could be a great product to use in your application.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb