There is no dispute that power densities have increased as cabinet volumes have gotten smaller. Packing components more densely reduces circuit size and increases speed but leaves little room for heat dissipation. Because industrial plants have become more dependent on sophisticated microprocessors, PLC's and VFD's, the need for proper heat dissipation has assumed critical proportions. Tightly packed cabinets and panels restrict airflow, resulting in rapidly rising internal temperatures and increasing control failures.

Thermal testing has proven that natural convection cooling is not adequate for today's smaller, high power density enclosures. Heat dissipation by forced convection (fan cooling) is the most frequently used method of enclosure cooling. Forced air-cooling systems can provide heat transfer rates that are 10 times greater than those achievable with natural convection and radiation, but even this is not adequate to cool faster electronic components when they are located in hostile plant environments.

It is necessary to lower the internal enclosure temperature to below the room temperature to reduce hot spot (junction) temperatures and prevent control failure on higher density controls. Research by control manufacturers has shown that for each 18° F (10º C) increase in temperature, online production shut-downs will occur twice as often - increasing the failure rate of electronics by 40 percent. Most manufacturers of electronic components specify a not-to-exceed limit of 104ºF (40ºC) and 90 percent humidity for proper operation.

The never-ending pressure to reduce the cost and size of electronics while increasing speed and complexity has created a significant design dilemma. Forced-air, fan cooling usually is selected by designers because fans are relatively inexpensive and easy to install. Unfortunately, the factory air pulled into the enclosure by the fans usually contains just enough nearly invisible oil aerosols to coat surfaces of sensitive and expensive electronic boards in control enclosures. This light surface coating of oil attracts and holds dust. The dust eventually forms an insulating blanket over the board, promoting heat buildup and eventually failure. Reliable, low cost, user friendly enclosure cooling is critical to keeping production lines operating.

Have You Considered Vortex Cooling?

Vortex enclosure coolers have come a long way in recent years. Models are available up to 5000 BTUH of cooling capacity, which are UL listed and maintain NEMA type 12, 4 and 4X ratings. Many of the NEMA 4X models competes very well with similarly rated refrigerant-type air conditioners because of their comparatively low purchase price and smaller size. Vortec offers several models that are controlled with an integral mechanical thermostat and valve, eliminating the need for mounting and wiring of a separate solenoid valve and thermo-switch, greatly simplifying installation. A recently released, Vortex A/C model eliminates one of the biggest objections to vortex type cooling -the high pitch "scream" that is inherent to all vortex tubes. These new units approved for NEMA 4/4X enclosures emit a relatively quiet, 62 dBA sound level -ideal for operator interface panels and still robust enough for harsh environments.

The Vortec brands, Vortex A/C and Vortex Cooler use a vortex tube to convert a filtered, compressed air supply into refrigerated air without the use of electricity, ammonia or other refrigerants. The vortex tube creates cold air and hot air by forcing compressed air through a generation chamber which spins the air centrifugally along the inner walls of the tube at a high rate of speed (1,000,000 rpm) toward a control valve. A small percentage of the hot, high-speed air is permitted to exit at the control valve. The remainder of the (now slower) air stream is forced to counter flow up through the center of the high-speed air stream, giving up heat, through the center of the generation chamber finally exiting through the opposite end as extremely cold air. Because there are no moving parts in a vortex tube, they are extremely reliable and low maintenance.

The cooled air produced by the tube inside the enclosure cooler is discharged at low velocity into the enclosure while hot air in the enclosure is vented outside the box into the surrounding area through an integral relief valve. The relief valve, baffling, and the cooler-to-enclosure seal maintain the integrity of NEMA 12, 4 and 4X boxes. Air introduced into the enclosure is filtered before it enters the vortex cooler, creating a clean, cool and controlled environment inside the enclosure helping to keep controlled processes up and running. An added benefit is that the enclosure cooler produces a slight positive pressure inside the cabinet to keep out dust and dirt.

Are Vortex Coolers suitable for hazardous locations?

Yes, but only if integrated into an approved purge system. Un-modified, Vortex Coolers must not be used for Class 1 or 2 hazardous locations. Even if they are allowed to operate continuously (without electric valve and thermostat) they are not approved for hazardous locations. One, because the vent air path through the Cooler will not contain or arrest incendiary particles (sparks). Two, because there are no controls to detect a loss of internal pressure if there is a malfunction. If used in conjunction with a purge/pressurization control system, modified Vortex Coolers can be, and are used for hazardous locations if the Cooler is designed in as part of the purge control system. Contact the purge control manufacturer for more information.

What if I just want to keep my enclosure at a slight positive pressure and it is not in a hazardous location?

If it is desired to cool the enclosure and maintain a slight pressure just to keep out infiltrating dust and dirt, and the enclosure is NOT in a hazardous location, then alternatives are available: One, the Vortex Cooler can be operated continuously without a thermostat, as long as the heat load remains fairly constant. Two, Vortex A/C models are equipped with a purge-air port that, when opened, will allow a small portion of low pressure air to "bleed off" into the enclosure to pressurize it, regardless of whether or not the unit is in the cooling mode or not. These models do not require an additional compressed air connection or mounting hole.

My Freon-type air conditioner is located near an oven and in the summer it "cuts out" when ambient temperatures get too high. Can I effectively use a Vortex Cooler or Vortex A/C here?

Yes. Vortex Coolers or the Vortex A/C will operate trouble-free in extreme temperatures and in dirty inhospitable environments. As long as the compressed air supply is kept properly filtered and dried, a Vortex Cooler will lower the incoming compressed air supply by 40 to 50 degrees Fahrenheit or more. Of course, avoid running the compressed air supply line near the oven.

I currently use a filter-fan to draw air into the enclosure. In the hotter summer months it cannot keep the controls cool enough. Can I install a Vortex Cooler and operate it with the fan during those hot months?

No, not efficiently. The fan will continue to pull in warmer humid air. The humidity in the ambient air will condense on the much colder Vortex Cooler components causing unwanted water droplets to form. You must remove the fan and filter and seal up the openings in the enclosure to prevent ambient air from entering the enclosure. The fan can be located inside the enclosure, if desired, to circulate the cold air.

How much inline pressure does a Vortex Cooler or Vortex A/C need?

These panel coolers are designed to use a filtered, factory compressed air supply of 80 to 100 psig. Unless compressed air pressures fluctuate widely or run considerably higher than 110 psig, do not use a pressure regulator to reduce the inlet pressure. Pressures lower than 80 psig, limit inline airflow into the enclosure, thus reducing the BTU/hr cooling capacities of the coolers.

What inlet line sizes do I install?

A Vortex Cooler enclosure cooler with up to a 5,000 BTU/hr capacity can be supplied using 3/8" schedule 40 pipe that has a drop (distance from the main supply) less than 10'. A ¾" schedule 40 pipe would be used for a distance up to 50'.

Rubber hose with a suitable pressure rating can be used to supply the coolers. A ½" hose is used in place of a 3/8" pipe; ¾" hose used in place of a ½" pipe; and 1" hose is used in place of a ¾" pipe. Only new rubber hose should be used to supply Vortex Coolers. A used rubber hose normally will have cuts on the inside wall (inside diameter) and be contaminated from inadequate filtration of particulate and oils. Select the compressed air line size appropriately and remember that lower inline pressures will produce a greater inline pressure drop and subsequent lower airflow and BTU/hr cooling capacity.

How do I remove moisture, dirt and oil from compressed air?

All compressed air systems will have condensed water, rust (scale) and dirt in the lines. To remove this contamination from the compressed air, a 5-micron filter separator with an automatic drain is provided with all Vortex A/C and Vortex Cooler systems.

A dryer usually is not required for proper operation, except when the normal relative humidity level is very high. A desiccant or refrigerated type dryer can be used in the inlet line to eliminate water vapor in the supply. The dryer should be rated to produce an atmospheric dew point lower than the output temperature of enclosure cooler.

If upon start up of the compressor every day, large amounts of water are produced, a bulk water removal filter should be used upstream of the 5-micron filter.

It is not necessary to supply lubricated air to a Vortex Cooler; in fact, excess oil and oil aerosols must be removed from the compressed air supply. Coalescing type filters are available for older compressors that have a lot of oil carryover.

Is maintenance required?

Because these cabinet coolers have no moving parts, they are reliable and require little maintenance. It is only necessary to change elements in the compressed air filter at regularly scheduled intervals. A minimum interval of six months is recommended; however; the cleanliness of the compressed air supply will determine the change frequency of the filter element.