Tag: NEMA 12

EXAIR Cabinet Cooler Systems provide heat protection for electrical enclosures, especially those in more “aggressive” environments. They’re durable & reliable, and unlike other devices (panel A/C, I’m looking at you), they’re impervious to environmental conditions and contamination…which they’ll also protect your electrical enclosures from. My colleague Jordan Shouse did a fabulous job of explaining how they work in a blog entitled (appropriately enough) “EXAIR Cabinet Cooler Systems – How Do they Work?” so I’ll get right to point of today’s blog, which is the selection process.

First, we need to calculate the heat load. If it’s for cooling a panel currently in operation, you need three things:

• Thermometer
• Tape measure
• EXAIR Cabinet Cooler Sizing Guide

You’ll use the thermometer to “take the panel’s temperature”. See, we calculate the internal heat load (that’s the amount of heat generated by the components inside the panel) by using the difference between the internal air temperature, and the external air temperature. Since we’re essentially air conditioning the panel, it’s important to get air temperatures (from a thermometer) rather than surface temperatures (from a heat gun or similar instrument).

You won’t need the thermometer for this, but we’ll also need to know the maximum ambient temperature in the area where the panel is installed. This is to calculate the external heat load, and also determine if a High Temperature model is needed (more on that in a minute).

The tape measure is to get the length, width, and height of the panel. We also need to calculate the heat transfer surface area. A ruler or yardstick would work as well.

If there’s something cooling the panel already – whether it’s panel A/C, fan circulation of environmental air through the panel, etc. – we’ll need to know about that too, because you’ll be removing that for optimal performance of the Cabinet Cooler System.

Once you have all that, you can enter the data (and a few other things, which I’ll get to momentarily) at the above link to the Sizing Guide. If you’re a DIY type person (or control freak…no judgment from ME on that), there’s also a link there to our new Cabinet Cooler System Calculator. You can also print a copy of the Sizing Guide and email it or fax it in. Or…you can call me with the data. It only takes a minute to do the calculation, and we do it over the phone all the time.

Next, we need to know about the environment in which it’ll be installed, so we can specify certain parameters like:

• NEMA rating. We make Cabinet Coolers for three distinct ratings, depending on the environment in which they’ll be installed.
  • NEMA 12 means it’s dust tight & oil tight, indoor duty. If no liquids or corrosives are present, this is probably what you’re looking for.
  • NEMA 4 means it’s dust tight, oil tight, splash resistant, indoor/outdoor duty. These have a low pressure relief valve for the Vortex Tube’s hot flow, and the exhaust from the panel, to maintain the splash resistant integrity of the panel.
  • NEMA 4X systems meet all requirements for a NEMA 4 rating, and are made of Type 303 Stainless Steel for corrosion resistance. We also make them in Type 316 Stainless Steel for higher levels of corrosion resistance, which is oftentimes specified in food and pharmaceutical environments.
• Ambient temperature. If they’re going to be installed in areas where the temperature can exceed 125°F, there are some internal components made of plastic & buna that aren’t rated for that. In those cases, we specify a High Temperature Cabinet Cooler, where we replace those with components made of brass and Viton, respectively. Those are good for up to 200°F environments.
• Atmospheric contaminants. All of our systems are, at a minimum, oil & dust tight per the above NEMA ratings. If a panel isn’t completely sealed – maybe there’s a cable bundle going through a loose grommet, or the door/front panel isn’t gasketed – then airborne stuff that you ideally want to keep away from sensitive electrical/electronic gear can still make it in. For those, we have two options:
  • Continuous operating systems will provide cold air flow for cooling and positive purge as long as compressed air is flowing to the Cabinet Cooler. That’ll keep the bad stuff out, but it’ll also get your panel colder than it needs to be, and you’ll pay for that with the increased cost of the full rated compressed air flow.
  • Non-Hazardous Purge systems allow Thermostat Control to turn off the compressed air flow when it’s not needed, and still pass 1 SCFM through the Cabinet Cooler (instead of full flow) when the internal temperature is at or below the Thermostat setpoint. These cost considerably less to run than Continuous Operation systems.
• Thermostat Control. Agencies like Compressed Air Best Practices and the Compressed Air Challenge include panel cooling on their list of inappropriate uses of compressed air – EXCEPT when they’re thermostat controlled. EXAIR uses Solenoid Valves operated by bimetallic thermoswitches with superior response times, so the Cabinet Cooler doesn’t continue running once it’s cooled the panel to the setpoint temperature, and (more importantly) comes on as soon as the temperature rises above that setpoint to further guard against heat damage. They’re available in 120VAC, 240VAC, and 24VDC options.

• Thermostat Control part 2. There are situations where the ability to change the regulated temperature is desirable. While the Thermostat’s setpoint can be changed, EXAIR’s ETC Electronic Temperature Control allows you to change it, at the push of a button. It also gives a continuous display of the actual temperature inside the panel that can alert operators to a potential overheating situation before the alarms start going off, or, if there are no alrms, before all those expensive electronic devices start to fry.

EXAIR’s Cabinet Cooler Promotion also started June 1st if you’re interested in purchasing one for your process. For a limited time, you can order any of EXAIR’s Cabinet Cooler® Systems and get a FREE AC Sensor with purchase! Check it out here.

If you’d like to discuss the ease at which you can provide safe, effective, and reliable heat protection for electrical panels in almost any environment, give me a call.

Russ Bowman, CCASS

Application Engineer
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