A customer contacted ITW Air Management: Vortec about an application for an ATEX Vortex AC enclosure cooler. The customer’s enclosure was in an ATEX Zone 2 location but the customer stated that the components within the enclosure were already rated and approved for the hazardous location, so they said there was no requirement for a purge system.
The customer wanted to know “can an ordinary locations NEMA 4 enclosure cooler be used on their enclosure?” or alternately they asked, “Would our ATEX Vortex AC unit function properly without a purge system?” It is always best to consult with your company’s safety engineer and/or certification engineer on situations like this but this is Vortec’s take on the matter:
An “ordinary location” enclosure cooler (ITW Vortec’s “Vortex Cooler”, “Panel Guard”, “Electric Vortex AC” and “Vortex AC”) models that are approved for NEMA 12, NEMA 4 or NEMA 4X locations are NOT approved by any agency for any type of hazardous location. There are two main hazards associated with some of these “ordinary location” enclosure cooler models and why it's important to use a "hazardous location" enclosure cooler:
- The 120 volt AC electric thermostat and solenoid valve in the “Vortex Cooler” and “Electric Vortex AC” product lines are not rated for any hazardous location.
- Most importantly, (and the reason that most people do not realize): the internal vortex tube on all these products generates hot exhaust air which creates hot temperatures on some of the external surfaces of the product. These surface temperatures can get very hot, in some cases-up to, and even exceeding, 250°F (121°C), depending on the temperature and pressure of the compressed air that the customer supplies to the enclosure cooler.
Therefore, none of Vortec’s “Vortex Cooler”, “Panel Guard”, “Electric Vortex AC” and “Vortex AC” models have any Temperature Classification (“T Code”) associated with them. If the hot surface temperature created on the enclosure cooler exceeds the auto-ignition temperature of the hazardous gas, dust or fiber in the area, then this obviously can be a huge problem! (Can you say “BOOM!”)
Another potential issue is related to the maintenance that the enclosure cooler and/or your compressed air filters receive. If the compressed air filtration is not maintained properly and dirt, or foreign materials, bypasses the filter(s), then this dirt can become lodged over time in the hot air path of the enclosure cooler. This can result in the blocking of the hot air path, altering the hot air fraction and leading to hotter surface temperatures on the enclosure cooler.
Therefore, even under controlled compressed air pressure and temperature conditions, an “ordinary location” enclosure cooler may seem to create “safe” hot exhaust surface temperatures when it is new, but over time if the compressed air supply is not filtered and maintained properly, it is possible that the hot surface temperatures could increase.
“Will our ATEX Vortex AC (or HazLoc Vortex AC or ProtEX Vortex AC) function properly without a purge system?” The answer to this is “no”, at least not without some additional equipment. Vortec’s HazLoc, ATEX and ProtEX Vortex AC models were designed for enclosures where the internal electronics are NOT approved for use in the hazardous environment.
"One of the most common ways to protect these types of enclosures is by the 'pressurization method' or Exp. With this method, a common NEMA 12, NEMA 4 or NEMA 4X enclosure can be used to house electrical components that are not rated for the hazardous area. A purge/pressurization system is used to keep the internal enclosure pressure slightly above the atmospheric pressure, thereby keeping the hazardous gas/dust/fiber out of the enclosure."
- Steve Broerman, Vortec Application Engineer
Therefore, our HazLoc, ATEX and ProtEX models were certified by Underwriters Laboratories and/or SGS Baseefa to be used in conjunction with an approved purge/pressurization system. When the hazardous location Vortex AC is not cooling the enclosure, it is not pressurizing it, and that is when the purge system keeps it pressurized at safe levels. If the enclosure’s electronics are rated for the hazardous location, then a purge/pressurization system may not be required. However, it’s best to check with your certification engineer.
A HazLoc, ATEX or ProtEX Vortex AC may be used on these enclosures without a purge system but the enclosure must be properly vented to allow the cooling air to escape (after it has lost it refrigeration) out of the enclosure so as not to over-pressurize the enclosure. There is no need for this vent to arrest sparks or incendiary particles because the electronics should not be capable of producing this hazard in the first place. Because the HazLoc, ATEX or ProtEX Vortex AC models are certified and approved for either a T3 or T4 Temperature Classification (depending on the model type), they can be used safely and with confidence in these situations.
In addition, all ProtEX Vortex AC models are supplied with a 5-micron automatic drain compressed air filter that has an integral pressure drop indicator. This pressure drop indicator can alert the user when the filter element needs to be changed, avoiding contamination in the ProtEX AC and reducing the chance of exceeding the Temperature Classification over an extended period of use.
It's important to fully understand the ratings that are required for specific locations. Be it "hazardous locations" or "ordinary locations" it is important to understand the safety regulations and equipment required to properly maintain an effective enclosure cooler. If you have any questions about our enclosure coolers, please do not hesitate to reach out to email@example.com.