of electronics in ordinary
or hazardous locations
10125 Carver Rd.
Cincinnati, OH 45242
There is no dispute that power densities have increased as enclosure volumes have gotten smaller. Packing
components more densely reduces the circuit size and increases speed but leaves little room for heat
dissipation. Because many industries, including manufacturing, food, chemical, water and wastewater
processing, oil refining and petrochemical processing and others, have become more dependent on
sophisticated microprocessors, PLCs and VFDs, the need for proper heat dissipation has become crucial to keep
controls protected. Tightly packed enclosures and panels restrict airflow, resulting in rapidly rising internal
temperatures, thermal runaway 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 cooling. Forced air cooling systems can provide heat transfer rates that are ten times greater than those
achievable with natural convection and radiation, but even those rates are not adequate to cool electronic
components when they are located in many plant environments, where ambient temperatures can often
exceed 90°F (32°C).
To reduce enclosure temperatures and prevent failure of high density controls, the internal enclosure
temperature must be lowered to below the room temperature. Research by control system manufacturers has
shown that for each 18F° (10C°) increase in temperature, online production shutdowns occur twice as often,
increasing the failure rate of electronics by 40 percent. Most manufacturers of electronic components specify
maximum operating conditions of 104°F (40°C) and 90 percent humidity for proper operation.
The never-ending drive to reduce the cost and size of electronics while increasing speed and complexity
has created a significant design dilemma. For enclosures located in ordinary locations (NEMA 12, 4 and 4X
environments, for example), forced-air fan cooling and refrigerant based air conditioning is usually selected by
designers because fans are relatively inexpensive and easy to install. Unfortunately, the factory air pulled into
the enclosure by fans often contains just enough nearly invisible oil aerosols or other contaminants to coat
the surfaces of sensitive, expensive electronic boards in control enclosures. Drawbacks of refrigerant based
air conditioning include limits on maximum ambient temperature, large physical size, maintenance and high
initial cost. For enclosures located in hazardous locations, cooling solutions are limited to just a few types of
technologies. While refrigerant based models can be built for hazloc environments, they are very expensive
and costly to maintain. Vortex cooling offers safe and reliable alternatives to the problems with these
conventional cooling methods.
A vortex enclosure cooler uses 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 and hot air by
forcing compressed air through a generation chamber that 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) airstream is forced to
counter-flow through the center of the high speed airstream, giving up heat as it travels through the center of
the generation chamber before it finally exits through the opposite end as cold air. There are no moving parts
in a vortex tube, so the systems are reliable, inherently safe and have low maintenance requirements.
The cold air produced is discharged at low pressure and low velocity into the enclosure, while the hot air in the
enclosure is vented outside the enclosure box through an integral relief valve. The relief valve, baffling and
cooler to enclosure seal maintains the integrity of NEMA rated boxes in ordinary locations.
Vortex cooling is also an ideal solution for cooling enclosures located in hazardous locations because they are
inherently safe when used in areas with temperature classifications of T4 or higher. There are no electrical
requirements and no moving parts to generate electrical charges. The only potential ignition source is the
hot surface at the hot exhaust. When supplied with compressed air that does not exceed 120°F (49°C), vortex
coolers are approved for Class I, II and III Division 2 or Zones 2 and 22 locations and can be used in ambient
temperatures up to 175°F (80°C) when used with an approved purge system.
The cooled air that is introduced into the enclosure is
filtered and dried to 5 microns before it enters the vortex
cooler, creating a clean, cool and controlled environment
inside the enclosure and helping to keep controlled
processes up and running. An added benefit is that the
vortex cooler produces a slight positive pressure inside
the enclosure to keep out dust and dirt. Hazardous
location models rely on a purge system to maintain
safe enclosure pressures when the vortex cooler is not
operating. An integral check valve keeps the enclosure
sealed when the unit is not cooling so the purge system
maintains enclosure pressure.
Vortex coolers are available in cooling capacities up to
5000 btuh (1465 watts). All ordinary locations models are
UL Listed and are controlled via an adjustable electric
or mechanical thermostat. Recently introduced electric
models are completely self-contained, are “plug and play”
and can be top or side mounted and maintain the NEMA
4/4X rating of the enclosure. Hazardous locations models
are UL Classified or ATEX approved and are regulated with
a fixed mechanical thermostat that maintains enclosure
temperatures between 75 to 100°F (24 to 38°C). The
typical high pitch noise that most people associate with
vortex tubes has been eliminated in all of the newer
models using a variety of sound abatement techniques,
reducing sound levels as low as 62 dB.
Compact, multifunction electronic controls, VFDs, servos and PLCs are extremely sensitive to heat and
contamination. Excessive heat causes components to “cook”, digital displays to misread, controls to drift, and
breakers to trip below their rated loads. The result often is lost productivity from machines and production line
Vortex coolers offer a solution. By using an internal vortex tube to convert factory compressed air into a clean,
dry, low pressure cold airstream that is distributed throughout the enclosure, these systems provide efficient,
safe and reliable enclosure protection from heat and dirt related problems for electronics in ordinary and
1. Are vortex coolers suitable for hazardous locations?
Yes, newer models are approved for Class I, II and III Division 2 or Zones 2 and 22 locations when used with
an approved purge system. All models have a temperature classification of T4.
2. My Freon 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 here?
Yes, vortex coolers 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 to 40 to 50°F (22 to 28°C) or more. Be sure to avoid running the
compressed air supply near the oven.
3. I currently use a filter-fan to draw air into the enclosure, but it cannot keep the controls cool enough in the
hotter summer months. 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 damaging water droplets to form.
You must remove the fan and filter and seal 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.
4. Is maintenance required?
Because vortex 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 level of cleanliness of the compressed air supply
will determine the change frequency of the filter element. If a dirty filter element reduces the pressure
available at the vortex cooler, the air consumption and the cooling capacity will drop. Mechanical
thermostat models require 90 to 100 psig (6.2 to 6.9 bar) to operate properly.
5. The components in my purged control panel are designed for ordinary locations and the panel is located
in a Class I, Div. 2 hazardous location. However the ambient temperature is greater than the design
conditions and the controls are malfunctioning during the hot summer months. Can I use an “ordinary
location” vortex cooler or is a hazardous location model necessary?
A hazardous locations model is required. Although the components are safe when enclosed in a purged
and pressurized enclosure, the vortex cooler must be able to maintain the Class and Division rating of the
panel. In addition, the size of the spark arrestor vent may need to be increased to accept the additional
cool air flow from the vortex cooler so desired enclosure pressure is not exceeded.