THINK ABOUT COOLING...EARLY! - Cooling needs
should be evaluated early in the design process. Nearly all systems require some
degree of forced cooling. Early estimates of the location of components in the cabinet,
the heat to be dissipated and the amount of space needed for the cooling device
will save time, trouble and expense.
FORCED VENTILATION VS. CLOSED-LOOP COOLING -
Keep it simple. If ambient air is cool and clean enough, use it. It’s free.
If the ambient is too hot, dirty or corrosive, a closed-loop system is needed. A
heat exchanger is usually a lower-cost choice than an air conditioner. See if it
will do the job. Don’t over-cool. Don’t oversize the cooling equipment.
FAN OR BLOWER? - Propeller fans are designed
to move large volumes of air at low static pressure.
Blowers are used in higher static pressure applications and are at maximum efficiency
when operating near their peak static pressure. Figure 2 shows their relative operating
PRESSURIZE, DON’T VACUUMIZE! - Pressurization
of the cabinet is far more desirable than drawing the air out. Plan to pump filtered
air INTO the cabinet, to gain the advantage of using cracks between panels, around
doors or other small openings as part of the exhaust area rather than as sources
for the intake of dust and dirt. If pressurization is impossible and a fan or blower
must be used to exhaust the enclosure, a filter at the air inlet is recommended.
KEEP IT CLEAN - Nothing is more important than
CLEAN filters. Clogged filters restrict airflow and cause motors, compressors, etc.
to work harder and fail prematurely. Timely filter servicing is vital to your system.
KEEP INLET AND EXHAUST AIR FAR APART - Be sure
that all of the exhaust area is located downstream, as far as possible from the
air inlet and beyond all heat-producing components. An open-base cabinet sitting
only one-quarter inch off the floor can waste a substantial percentage of cooling
air even if the air is directed upward initially. A properly planned air path will
avoid all “short circuits” or losses by forcing the cool supply air
to pass through the components that are to be cooled before reaching the exhaust
area. This will allow for a maximum of cooling efficiency.
LET NATURE HELP - Cooling air should enter the
enclosure from as low as possible and leave the enclosure from above the highest
hot component. Thus, the forced air flows upward through the heat-producing components
adds to the natural buoyancy of the heated air.
A “BOOSTER” CAN SAVE SPACE AND COST
- A booster fan located downstream or at the outlet can draw added cooling power
through densely packed components. It could permit the use of a smaller, quieter
packaged blower than originally indicated, allowing more panel space for other uses.
ENTERING AIR NEEDS EXIT ROOM - The cross-section
area of the airstream throughout the flow path in the cabinet should be at least
equal to the effective area of the air intake. If this ratio is less, “choking”
of the delivered air may result. The table shown on the right gives the recommended
area which should be available for discharge.
For intake and exhaust grille and filter grille assemblies, see the Accessories
and Options sections.
USE DUCTS FOR EVEN COOLING - If the maintenance
of an even temperature from top to bottom of the enclosure is important, ducts along
the sides of the enclosure offer an ideal solution. Multiple duct outlets allow
precise control of the location and quantity of air delivered.
COMPONENT LOCATION - Where possible, locate
heat sensitive electrical components toward the bottom of the enclosure, since the
warmest air temperatures will be at the top. Maintain adequate spacing between components
within the enclosure to minimize airflow restriction.
BAFFLES SOMETIMES WORK WONDERS - At times, an
excessively hot component or an isolated area in the enclosure presents a problem
in an otherwise well-cooled system. A baffle to channel air across the location
is often the best solution.
VIBRATION ISOLATION - Neoprene vibration isolators
minimize the possibility of trouble associated with vibration. All portions of a
system will respond to periodic forces in varying degrees. This excitation can occur
regardless of the balance or design of the air-moving equipment, since any given
construction could be in resonance with any of the driving forces in the blower
motor. If the sympathetic vibration level is unacceptable, slight weight change
or redistribution will usually alleviate the problem.
CALL KOOLTRONIC FOR HELP - For help with your
design problems or to resolve questions, give us a call.