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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316 Stainless Steel Products- Always in Stock

Metallurgically speaking, stainless steel is a steel alloy with the highest percentage contents of iron, chromium and nickel, with a minimum of 10.5% chromium content by mass, and a maximum of 1.2% of carbon by mass.

Stainless steels are widely regarded for the corrosion resistance that they exhibit. As the chromium content is raised, the corrosion resistance increases as well. The addition of molybdenum also increases the corrosion resistance to reducing acids and against pitting attacks in chloride solutions. By varying the chromium and molybdenum content, different grades of stainless steel are produced with each suited for varying environments. Due to the resistance to corrosion and staining, stainless steel is ideal material for many applications, especially in the food, pharmaceutical, and chemical industries.

The 300 series stainless steels are considered chromium-nickel alloys and is the largest group and most commonly used. Of the different compositions within the 300 series family, Type 304 stainless is the most widely used followed by Type 316, which has 2% molybdenum added to provide greater resistance to acids and to localized corrosion caused by chloride ions.

Table below shows the nominal composition by mass content for 316 stainless steel

316 SS Table

Because 316 stainless steel provides a high level of corrosion resistance, resists pitting, and has good strength properties, EXAIR manufactures many of its products from 316 stainless steel material so that they can be used in the harshest of environments.

Of the EXAIR products these are available off the shelf in 316 stainless steel- Super Air Knife, certain sizes of Adjustable Air Amplifiers, numerous Air Nozzles, Line Vacs including the Sanitary Flanged style, NEMA Type 4X and Hazardous Location Cabinet Coolers. If you need one of our other products such as the Super Air Wipes or Vortex Tubes made in 316 stainless steel, just let us know. Of course we also have them made from Type 303 stainless steel, in stock and ready for shipment (and aluminum, too!)

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316 Stainless Steel Super Air Knife

And, you don’t have to wait months or even weeks, as we keep all of these in stock, ready for shipment.

If you have questions about any of the 15 different EXAIR Intelligent Compressed Air® Product lines, feel free to contact EXAIR and myself or any of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer
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Cabinet Cooler NEMA Ratings Explained

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Temperatures are heating up across the US, when this happens it can wreak havoc on the sensitive electronics in your facility.  If you’re a follower of the EXAIR Blog, you’ve noticed that we’ve spent a great deal of time recently discussing the Cabinet Coolers. From a description of how they work, specific applications, as well as how to determine what size you’ll need, we’ve covered quite a range of topics. Equally important, though, is the NEMA rating of the Cabinet Cooler. I’d like to take a moment to discuss the different NEMA ratings for the Cabinet Coolers that EXAIR has to offer and where each should fit.

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EXAIR’s Model 4008 Nema 12 Cabinet Cooler

NEMA 12 – The NEMA 12 rating is for enclosures that are indoor and provide a degree of protection to personnel against access to hazardous parts as well as prevent any materials from entering the enclosure such as dust, debris, or moisture from light splashing. This standard duty style of Cabinet Cooler is best served indoors on the shop floor where there aren’t any wash-down areas or excessive moisture.

EXAIR PR Hero Images
Model 4880-ETC120

NEMA 4 – A NEMA 4 rated cabinet cooler is designed for either indoor or outdoor use. It, too, provides protection to personnel against access to hazardous parts and prevents dust, dirt, or debris from entering the cabinet. In addition to providing the same levels of protection as the NEMA 12, the NEMA 4 rating also means that the equipment will be protected from water such as rain, sleet, snow, splashing water, and even hose directed water.

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Model 4880SS-316

NEMA 4X – The NEMA 4X carries the same levels of protection as the NEMA 4, but also adds an additional level of protection against corrosion. EXAIR’s NEMA 4X Cabinet Coolers are constructed of either 303 or 316 Stainless Steel.

EXAIR’s Cabinet Coolers are available from stock with cooling capacities ranging from 550 Btu/hr – 5,600 Btu/hr. With a variety of different materials and NEMA ratings, EXAIR has the right Cabinet Cooler ready to ship today to prevent your sensitive electronics from shutting down. Don’t let yourself get frustrated dealing with heat-related issues, get a maintenance-free Cabinet Cooler installed ASAP! Fill out the Cabinet Cooling Sizing Guide and an Application Engineer will be in touch with you within 24 hours with a quote for the most suitable model.

Tyler Daniel
Application Engineer
E-mail: TylerDaniel@EXAIR.com
Twitter: @EXAIR_TD

EXAIR’s Cabinet Coolers Solve Your Overheating Problems

We here at EXAIR always know when summer is approaching, as phone calls and orders for the Cabinet Cooler Systems start to kick into high gear.  After those first few hot days in late spring, it is common for panels and electrical enclosures to overheat due to faulty air conditioning units, fans that are not working, or lack of a cooling system in general.

Time for us to sharpen our pencils and be ready to help! Our Cabinet Coolers are in stock and ready to solve your overheating problems with same day shipping on orders we receive by 3pm. If you need assistance choosing your Cabinet Cooler Solution, Contact an Application Engineer today!

The Cabinet Cooler System is a low cost, reliable way to cool and purge electronic control panels.  We recently hosted a Webinar on the systems, and it is available for review (click picture below)  webinar-on-demand

EXAIR Cabinet Coolers incorporate the vortex tube technology to produce cold air from compressed air, all with no moving parts.

Below shows the basics of how the Cabinet Cooler is able to provide cooling to an enclosure.  Compressed air enters the vortex tube based system, and (2) streams of air are created, one hot and one cold. The hot air is muffled and exhausted through the vortex tube exhaust.  The cold air is discharged into the cabinet through the Cold Air Distribution Kit and routed throughout the enclosure. The cold air absorbs heat from the cabinet, and the hotter air rises to the top of the cabinet where it exits to atmosphere under a slight pressure. Only the cool, clean, dry air enters the cabinet – no dirty, hot humid outside air is ever allowed into the cabinet!

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How the EXAIR Cabinet Cooler System Works

EXAIR offers Cabinet Cooler Systems for cabinets and enclosures to maintain a NEMA rating of NEMA 12 (dust tight, oil-tight), NEMA 4 (dust tight, oil-tight, splash resistant, indoor/outdoor service) and NEMA 4X (same as NEMA 4, but constructed of stainless steel for food service and corrosive environments.

Cabinet Cooler Systems can be configured to run in a Continuous Operation or with Thermostat control. Thermostat control is the most efficient way to operate a Cabinet Cooler.  They save air by activating the cooler only when the internal temperature reaches the preset level, and are the best option when fluctuating heat loads are caused by environmental or seasonal changes. The thermostat is preset at 95°F (35°C) and is easily adjusted.

Another option is the ETC Electronic Temperature Control, a digital temperature control unit for precise setting and monitoring of enclosure conditions. An LED readout displays the internal temperature, and the use of quick response thermocouple provides real time, accurate measurements. The controller has easy to use buttons to raise or lower the desired cabinet temperature set-point.

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EXAIR NEMA 4X 316SS Cabinet Cooler System with Electronic Temperature Control installed on control panel in a pharmaceutical plant.

 

Other Special Cabinet Cooler considerations are:

  • High Temperature –  for ambient temperatures of 125°F to 200 °F – for use near furnaces, ovens, etc.
  • Non-Hazardous Purge – ideal for dirty areas where contaminants might normally pass through small holes or conduits. A small amount of air (1 SCFM) is passed through the cooler when the solenoid is in the closed position, providing a slight positive pressure within the cabinet.
  • Type 316 Stainless Steel – suitable for food service, pharmaceutical, and harsh and corrosive environments.

If you have any questions about Cabinet Coolers or any of the EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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Twitter: @EXAIR_BB