For sensitive electronics, environmental control is
more than simple cooling. “Comfort” air conditioning
systems are designed for the comfort of people and
simply cannot provide the kind of environment
required by high performance computer or communi-
cation equipment.
The high density heat load in a computer room
or other similar application is beyond the
capacity of ordinary air conditioning systems.
Sensitive electronics are best maintained in a stable
environment of 72°F ±2°F (22.2°C ±1°C). Because
computers and communications equipment generate
large quantities of heat in small areas, six to 10
times the heat density of normal office space, the air
conditioning system must have more than just
enough cooling capacity. It must have the precision
to react quickly to a drastic change in heat load and
prevent wide temperature fluctuations—something a
large building system cannot do.
The electronic equipment must be protected
from both internal condensation and static
electricity discharges.
Maintaining the correct humidity level in the room is
just as important as maintaining proper tempera-
ture. When humidity is too high, condensation may
form inside electronic equipment and damage it. If
humidity is too low, static electricity could disrupt
operation or even shut down the electronic system.
An ordinary building system cannot normally control
the environment within these boundaries.
Computers and other sensitive electronics require
greater air volumes than ordinary air conditioning
can provide. Typical comfort systems are designed to
provide between 300 and 400 CFM (cubic feet per
minute), (500–700 CMH) per ton of cooling. Com-
puter systems require between 500 and 600 CFM
(850–1020 CMH) per ton. The high density heat load
in a relatively small space requires more changes of
air than a less dense “comfort” application.
While a normal office space requires only two air
changes per hour, a room filled with electronic equip-
ment requires up to 30 changes per hour. Without
proper air volume, hot spots and temperature fluctu-
ations could develop within the room. Also, greater
air volumes provide the higher sensible heat ratios
required by electronic computer equipment.
A clean environment of properly filtered air is essen-
tial. Build-up of dust and fibers attracted by operat-
ing electronics can cause faults and impair the
operation of electromechanical devices, such as
switches and disk drives.
In short, today’s electronics need the same precision
environmental control that mainframe computers
need. The difference is that instead of one large com-
puter room there are several small, often crowded
rooms, widely dispersed throughout a building, plant
or campus. Conditions and requirements can vary
widely.
Comfort conditioning systems cannot be relied upon
24 hours per day 365 days per year. They are typi-
cally designed to operate 10 hours per day, from
spring to autumn. Many “comfort” systems have no
provision for winter operation. A precision environ-
mental control system is designed for operation at
temperatures down to -30°F (-34.4°C).
Standard 60 Hz
units are UL
listed and CSA
(NRTL-C) certi-
fied. NRTL-C
meets both U.S.
and Canadian
government safety requirements, providing fast, has-
sle-free inspection and building code approvals. The
units are also MEA listed for New York City applica-
tions.
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