The Basics of Calculating Heat Load for Cooling Electrical Cabinets

Is your electrical cabinet overheating and causing expensive shut downs? As spring and summer approach, did your enclosures have seasonal overheating problems last year? Is your electrical cabinets AC Unit failing and breaking down? Then it may be time to consider EXAIR Cabinet Coolers Systems. These systems are compressed air powered cooling units designed to keep your cabinet cool in hot environments. Major benefits include no moving parts to wear out, UL listed to maintain the NEMA integrity of your enclosure (also CE compliant), they are simple and quick to install and they reliably turn on and off as needed (perfect for solving seasonal overheating).

Just one question then; how do you pick which Cabinet Cooler is best for your application? It’s time to bust out ye ole trusty calculator and crunch some numbers. Keep in mind that the following calculations use baselines of an Inlet air pressure of 100 psig (6.9 bar), compressed air temperature of 70F (22C), and a desired internal temp of 95F (35C). Changes in these values will change the outcome, but rest assured a Cabinet Cooler system will generally operate just fine with changes to these baselines.

How the EXAIR Cabinet Cooler System Works


Before we dig right into the math, keep in mind you can submit the following parameters to EXAIR and we will do the math for you. You can use our online Cabinet Cooler Sizing Guide and receive a recommendation within 24 hours.

There are two areas where we want to find the amount of heat that is being generated in the environment; this would be the internal heat and the external heat. First, calculate the square feet exposed to the air while ignoring the top. This is just a simple surface are calculation that ignores one side.

(Height x Width x 2) + (Height x Depth x 2) + (Depth x Width) = Surface Area Exposed

Next, determine the maximum temperature differential between the maximum surrounding temperature (max external temp) and the desired Internal temperature. Majority of cases the industrial standard for optimal operation of electronics will work, this value is 95F (35C).


Max External Temp – Max Internal Temp Desired = Delta T of External Temp

Now that we have the difference between how hot the outside can get and the max, we want the inside to be, we can look at the Temperature Conversion Table which is below and also provided in EXAIR’s Cabinet Cooler System catalog section for you. If your Temperature Differential falls between two values on the table simply plug the values into the interpolation formula.

Once you have the conversion factor for either Btu/hr/ft2, multiply the Surface Area Exposed by the conversion factor to get the amount of heat being generated for the max external temperature. Keep this value as it will be used later.

Surface Area Exposed x Conversion Factor = External Heat Load

Now we will be looking at the heat generated by the internal components. If you already know the entire Watts lost for the internal components simply take the total sum and multiply by the conversion factor to get the heat generated. This conversion factor will be 3.41 which converts Watts to Btu/hr. If you do not know your watts lost simply use the current external temperature and the current internal temperature to find out. Calculating the Internal Heat Load is the same process as calculating your External Heat Load just using different numbers. Don’t forget if the value for your Delta T does not fall on the Temperature conversion chart use simple Interpolation.

Current Internal Temp – Current External Temp = Delta T of Internal Temperature
Surface Area Exposed x Conversion Factor = Internal Heat Load

Having determined both the Internal Heat Load and the External Heat Load simply add them together to get your Total Heat Load. At This point if fans are present or solar loading is present add in those cooling and heating values as well. Now, with the Total Heat Load match the value to the closet cooling capacity in the NEMA rating and kit that you want. If the external temperature is between 125F to 200F you will be looking at our High Temperature models denoted by an “HT” at the start of the part number.

From right to left: Small NEMA 12, Large NEMA 12, Large NEMA 4X

If you have any questions about compressed air systems or want more information on any of EXAIR’s products, give us a call, we have a team of Application Engineers ready to answer your questions and recommend a solution for your applications.

Cody Biehle
Application Engineer
EXAIR Corporation
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Static Eliminators Essential To Packaging Operations

I had a headache the other day. Of all the things that can make me grumpy, nothing makes me grumpier than a headache. Luckily, there are over the counter medications that work quite well, and quickly, to boot.  And I had a brand new bottle of them in the cabinet.

When I opened the package and removed the tamper-resistant plastic band on the cap, it stuck to my hand when I went to drop it in the trash can.  This raised my grumpiness just a touch.  I shook my hand to try and get it off, and it fell behind the trash can.  My grumpiness elevated a bit further.  I hit my head (you know, the one I was trying to cure the pain in?) on the counter while bending over to retrieve it.  That activated my grumpiness alarm, which sounds just like mild profanity.  My wife silenced that alarm pretty quickly.

The plastic band stuck to my hand, of course, because it’s made of a non-conductive material, and peeling it from the bottle cap, which is also a non-conductive material, generated a static charge.  As a subject matter expert on the topic of static elimination, I am quite familiar with the phenomenon, the problems it causes, and, more importantly, the numerous ways to apply solutions to those problems:

  • One such solution was related to my problem with the tamper-resistant seal.  A mouthwash manufacturer was actually having trouble getting those seals ONTO the bottles on their packaging line.  The bottle caps themselves had so much static charge on them that they repelled the seal as the machine tried to drop it in place before heat shrinking it.  An Ion Air Jet solved the problem:
Gen4 Ion Air Jet ensures bottle caps & necks are static free for application of tamper resistant seals.
  • Speaking of plastic bottles, the finishing process after extrusion can leave small bits of plastic particulate behind, and static charge can keep them on the bottle.  This was a great fit for an Ion Air Cannon:
Gen4 Ion Air Cannon eliminates static & dust prior to filling bottles.
  • Sometimes, air flow isn’t necessary, like in the case of a film that is eventually made into single-use condiment packages, with a static charge that was high enough to fry the print heads that apply the label text.  An Ionizing Bar protects those print heads:
Initial static charge of almost 17kV (left) is almost completely dissipated by the Ionizing Bar (center) to just 0.04kV (right)

EXAIR Corporation’s Gen4 Static Eliminator product line offers a wide variety of options for total static control.  If you need to get rid of nuisance shocks, clinging dust, tearing, jamming or curling of material, misfeeding sheets or rolls, or any of the numerous other problems that static charge can cause, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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What’s So Great About The Gen4 Ion Air Cannon Static Eliminator?

It’s bitter cold this week in southwest Ohio, and one of the consequences of that is dry air in heated indoor areas.  If you’ve walked across a carpeted floor and pet your cat (like I did the other day), you (and your cat) may have experienced a phenomenon known as dissipation of static electricity.

In my defense, Elle The Cat often looks down on me just like she does on Rocky The Dog. Neither of us care.

The relatively low static charge you pick up by shuffling your socks across the rug is pretty small, compared to the charge generated by:

  • High speed rolling & unrolling of plastic film on a shrink wrapper.
  • Plastic pellets traveling through a conveyor system to an injection molding machine.
  • Slitting or trimming of paper, laminates, sheets, etc.
  • Removing protective layers between sheets of delicate materials.

And these can cause issues year-round.  The problems associated with static charge in these situations include:

  • Nuisance shocks to operators.
  • Dust and debris clinging to product finishes and surfaces
  • Product clumping or clinging while in transit.
  • Thin sheets tearing, jamming, folding, or misfeeding.
  • Disruption of sensitive electronic sensors, switches, etc.

EXAIR Corporation has a variety of Static Eliminator Product solutions, depending on the specific needs of a particular application.  To answer the question in the title of this blog, though, the Gen4 Ion Air Cannon is quite versatile, and is often considered alongside our other products.  For example:

  • Gen4 Super Ion Air Knives come in lengths from 3 inches to 9 feet.  If you have a wide web, sheet, or plate to remove static charge from, they’re the best choice, hands down.  For narrower widths, or situations where you have to blow in from the side or at a certain angle due to physical interference, the Gen4 Ion Air Cannon’s small footprint and adjustable mounting bracket provide a great workaround.
  • Gen4 Ion Air Jets generate a focused, concentrated flow of ionized air, for spot cleaning of smaller parts.  Its compact design is ideal for installations in close quarters.  If you have some room, the Gen4 Ion Air Cannon actually uses less compressed air to generate a higher ionized air flow…and it’s quieter, to boot.
  • Gen4 Super Ion Air Wipes are made to blow off and remove static from pipe, cable, extruded shapes, etc.  They come in 2″ or 4″ diameters.  If your product is larger than that, an array of Gen4 Ion Air Cannons can accommodate that.
  • Gen4 Ionizing Points are often installed in ducts to ionize existing air flow.  Arrays of two, three, or four are suitable for ducts up to about 6″ in diameter, depending on the air flow rate.  For larger ducts (or very high flow rates,) Gen4 Ion Air Cannons can be installed to blow into a ‘Y’ connection in duct walls.

Regardless of the nature of the application, if you’ve got a static problem, EXAIR has a solution!

These are just a few of the myriad Static Eliminator applications that EXAIR Corporation has successfully solved over the years.  Many times, the details of the application make one particular product the clear choice.  When there ends up being more than one worth consideration, one of the others is usually the Gen4 Ion Air Cannon.

Again…that’s based on the details of the application, and we’re here to help with that.  If you’ve got a static problem, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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Five Things To Know About Single Acting Reciprocating Compressors

With the development of highly efficient air compressors, there’s still a place for the most basic design: the single acting reciprocating compressor.  When the piston moves out of the cylinder, it draws air in, at atmospheric pressure.  When it moves in to the cylinder, it reduces the volume that air occupies, increasing its pressure.  These machines are durable, effective, relatively inexpensive, and pretty easy to maintain.  Here are a few interesting things to know about them:

1. Popularity. Because of the simplicity of their design, they’re the most common air compressor in the 10HP and under sizes.  You can get them from a number of sources, and they’re not going to set you back as much as some other types.
2. Oil free air (part 1) While the most basic design uses oil to lubricate the piston rings in the compression cylinder, oil-less reciprocating compressors have cylinders with very smooth (and hard) bore surfaces, like nickel or chrome plating. A series of guide rings around the whole circumference of the piston prevent metal-to-metal contact, eliminating the need for liquid lubrication in the compression cylinder.
3. Oil free air (part 2) If oil in your compressed air is a problem, an oil-free (as opposed to oil-less) compressor is another option. While an oil-less compressor doesn’t use lubricant for the piston movement, an oil-free compressor’s moving parts are oil lubricated, but that oil is kept away from the compression cylinder(s) with connecting rod(s) so that the oil is confined to the lower moving parts…the crankshaft and bottom ends of the connecting rods, and away from the pistons & compression cylinders.
4. Foundation. Reciprocating machinery, as the name implies, has parts that move back and forth. The sudden reversal of direction of heavy metal pistons & rods, dozens of times a minute, means that their operation is inherently unbalanced. This out-of-balance condition, though, can be absorbed by properly securing the compressor to a properly prepared foundation.
5. Higher pressures. If your facility’s compressed air usage primarily entails pneumatic tools, cylinders, and blow off devices like air guns, the system header pressure is likely maintained at around 100psig. While a one-stage reciprocating compressor is usually rated for discharge pressures up to 125psig, a second stage can increase that to 175psig. Multi-stage compressors are used for applications that require up to 3,000psig compressed air. Examples of these are scuba breathing air, pneumatic excavators, and my personal favorite: ballast tank blowing air, used to surface a submarine.

4-stage reciprocating compressors charge 3,000psig air tanks that are used to rapidly push water from a submarine’s ballast tanks to create positive buoyancy.  Because keeping your ‘diving-to-surfacing’ ratio at 1:1 is important.

At EXAIR Corporation, helping you get the most out of your compressed air system is important to us.  If you’ve got questions about how to do just that, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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