Let’s Size A Cabinet Cooler System!

I can’t remember the last time I put an exclamation point in the title of my blog, but it was probably the last time I got to talk about doing math. Or write about heat transfer.  Insert your favorite engineer joke here…I’m sure I have it coming.

We’re in the dog days of summer (in the Northern Hemisphere) for sure…or, as we call it, “Cabinet Cooler Season.”  If you’re having heat related problems with a control panel, give us a call; we can help.  If you’d like to know what we’re going to talk about, read on.

Heat can cause real problems for electrical and electronic components, in a hurry…we all know that.  Fortunately, we can also specify the right Cabinet Cooler System for you in a hurry too.  And since we keep them all in stock, we can get it to you in a hurry as well.

You can access our Cabinet Cooler Sizing Guide online, here.  You can fill in the blanks and submit it, or you can call in your data.  We do it over the phone all the time, and it only takes a minute.  Here’s what we’re going to ask for, and why:

Enclosure dimensions.  We need the length, width, and height of your enclosure to calculate the heat transfer surface, and the volume of the enclosure.

Current Internal Air Temperature.  How hot is it inside your enclosure?  This is the starting point for figuring out the internal heat load…how much heat the components inside the box is generating.  This needs to be the air temperature – don’t use a heat gun, or you’re going to give me the surface temperature of something that may or may not be close to what I need.  Just put a thermometer in there for a few minutes.

Current External Air Temperature.  How hot is it in the area where the enclosure is located?  We’re going to compare this to the internal air temperature…the difference between the two is actually proportional to the heat load.  Also, if there’s anything cooling the enclosure right now (like circulating fans; more on those in a minute,) this reading is key to figuring out how much heat they’re removing.

Maximum External Air Temperature.  How hot does it get in the area on, say, the hottest day of summer?  We’ll need this to calculate the external heat load…how much heat the enclosure picks up from its surroundings.

Maximum Internal Temperature Desired.  Most electrical and electronic component manufacturers publish a maximum operating temperature of 104F (40C) – it’s kind of an “industry standard.”  Based on this, a lot of us in the enclosure cooling business set our products’ thermostats to 95F (35C) – if we’re maintaining the air temperature a decent amount cooler than the components are allowed to get, history and practice has shown that we’re going to provide more than adequate protection.  If your enclosure houses something with more sensitive temperature limitations, though, we can work with that too…that’s the only time you’re going to want to put something other than 95F (35C) in this field.

Cabinet Rating.  This is all about the environment…we offer three levels of protection, per NEMA standards:

NEMA 12 – oil tight, dust tight, indoor duty.

NEMA 4 – oil tight, dust tight, splash resistant, indoor/outdoor duty.

NEMA 4X – oil tight, dust tight, splash resistant, corrosion resistant, indoor outdoor duty.

The NEMA rating does not affect the cooling capacity at all.

Other:  If the enclosure is mounted to the side of a machine, or a wall in the plant, you really don’t need to put anything here.  If it’s outside and exposed to direct sunlight, tell us what the surface finish (i.e., polished metal, painted grey, etc.) is so that we can account for solar loading too.  If anything else is unusual or peculiar about the application, let us know that too.

My Cabinet Is…Not Vented, Vented, Wall Mounted, Free Standing, Fan(s).  We’ll use what you tell us here to verify heat transfer surface (a wall mounted cabinet’s back surface isn’t a radiative surface, for example.)  Also, I mentioned fan cooling before, so without further ado…

Fan diameter or SCFM.  If there are fans circulating air into (and/or out of) the enclosure, they’re providing a finite amount of cooling right now.  Proper installation of a Cabinet Cooler System is going to require their removal.  Running a Cabinet Cooler System on a vented enclosure is just like running your air conditioner with the windows open.  So, if we know the size (or the SCFM…sometimes there’s a label on those fans, and we LOVE those folks who do that) then we can use that, and the temperatures you gave us above, to take the fan cooling into account.

Once we have all this information, it’s down to the math. Like I said, we do this all the time (especially during “Cabinet Cooler Season”) – give me a call.  Your heat problem isn’t waiting; why should you?

Before I go…here’s a nice little video, walking you through the Cabinet Cooler Sizing Guide.  Yes, I just made you read the book before watching the movie…feel free to tell me which one you liked better.

Russ Bowman
Application Engineer
EXAIR Corporation
Visit us on the Web
Follow me on Twitter
Like us on Facebook

Video Blog: Measuring Surface Temperature and Air Temperature Requires Different Tools

IR Temperature Guns are a great tool for measuring surface temperatures, but not the best solution for providing the air temperature data EXAIR needs to size a Cabinet Cooler system for your electronic cabinets. This brief video illustrates the differences between using an IR temp gun and a regular thermometer when gathering temperatures to determine Cabinet Cooler system specifications.

Make sure to print out the Cabinet Cooler Sizing Guide before you get started so you can easily fill in all the needed data.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

Can We Help Identify Your Existing EXAIR Product? – Yes.

From time to time we have customers call in and say “We have one of your products and need another. But we installed it so long ago that we no longer have the paperwork to know which model we bought.” That’s a great thing to hear in a way. Our products have outlasted their filing system, and not only that, but now we have potential to solve another problem for the same customer.

When this happens, we can sift through our files to find out which model was purchased, or if the original purchase was made through a third party, we can determine the model number in other ways. We can use the dimensions, material of construction, description over the phone, or a photo emailed to an Application Engineer such as the one below.

Cabinet Cooler

But, the needs of the application don’t end there. We may be able to pinpoint the model number of the device currently in use, but we also need to confirm that this model will be suitable for the new application. For the end user that sent in the photo above, this meant the completion of a Cabinet Cooler Sizing Guide for new heat load calculation.

What we determine in many cases is that the new application has specific needs which dictate the use of a product with different attributes (in this case a different Btu/Hr rating on a Cabinet Cooler). Whether it is because of heat load, ambient temperature concerns, required material, or any other variable, we are sure to provide the most suitable solution.

As spring gains momentum and warmer months are to come, it may be time to consider an EXAIR Cabinet Cooler solution for an overheating electrical panel in your facility. Contact an EXAIR Application Engineer for help calculating heat load and choosing the right system.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE