I was working with a customer several weeks ago. He did not think he had enough air to make the cabinet cooler work. He filled out a Cabinet Cooler Sizing Guide so EXAIR could assist with determining his heat load and recommend the most efficient model number for the application. His cabinet is 48 inches tall, 36 inches wide and 12 inches deep. The internal temperature inside the cabinet with the electronics running reached 130 degrees Fahrenheit. The ambient temperature was 80 degrees Fahrenheit. The maximum external temperature possible is 115 degrees Fahrenheit. The cabinet was rated for a NEMA 12 enclosure. The NEMA 12 rating is dust and oil resistant , but will not prevent water intrusion.
With all this information, I calculated that my customer needed a model 4325-ETC120 NEMA 12 Cabinet Cooler System with Electronic Thermostat Control. The 4325-ETC120 Cabinet Cooler will use 25 SCFM of compressed air at 100 PSIG. The customer was designing a cooling system for an oil drilling operation. 25 SCFM of compressed air can be difficult for some facilities to generate, but oil wells typically have a compressor capable of putting out enough compressed air to power our products.
After sharing my recommendations with the customer, he was very disappointed that he did not think he would have enough Instrument Air to operate the equipment. The instrument air was tripping us up. Cabinet Coolers require clean, dry compressed air. They do not need instrument air. The cabinet coolers will run on instrument air, but it is not necessary in almost all applications.
Instrument air or control air is typically a special compressed air system used primarily inside pneumatic control devices or sensitive instruments. In these systems dew point, oil concentrations and particulate filtration are closely monitored to ensure that controls are not damaged. Equipment vendors specify oil concentration limits, and not all instrument air systems share the same parameters. In every facility instrument air is more expensive than shop air or compressed air. You can use instrument air to power cabinet coolers, but it typically is not necessary. On the rare occasions that the vortex tube will be mixed with air that is actually going through a sensor or instrument, instrument air is required. This distinction will have a significant impact on the cost to operate a vortex based cooling system on your electrical enclosures.
My customer was trying to use instrument air, because he believed the standard house air would not work. In many cases standard house air will work, especially when a Automatic Drain Filter Separator, and/or and oil removal filter are used. The Cabinet Coolers feature no moving parts to wear out, but dirty air could block the air flow though the cooler over time so we do recommend a filter on any shop air supply. Instrument air is far more costly to produce than standard shop air. The customer was not interested in providing instrument to cool his cabinet. This is completely understandable. After I explained to him that using filtered compressed air, the cabinet cooler would be more than capable of cooling his troublesome cabinet, he was able to utilize the Cabinet Cooler. The lower operational cost of the shop air over the instrument air was able to make the Cabinet Cooler a great solution.