TM
5-858-7
CHAPTER 4
AIR-QUALITY
CONTROL
b. Where personnel efficiency is the prime con-
41.
Introduction.
sideration, the average effective air temperature
a. This chapter deals primarily with quality con-
trol of the air required to support personnel. Ref-
erence is made to operating equipment when nec-
order to permit combined cooling and dehumidifi-
essary, but does not address the quantity (or
cation at moderate coolant temperatures. (The in-
quality) of air needed for combustion systems.
dicated dry-bulb and effective temperatures to-
View the air-quality control system within the con-
gether with an air velocity of 100 ft/min are
text of two operation modes: preattack, and
consistent with a relative humidity of 50 percent,
transattack/postattack. In general, it will be most
which is also considered the optimum for control of
effective to use an open ventilization system during
air-borne bacteria. )
the preattack time frame. The design of this sytem
is similar to the ventilation systems found in con-
c. For facilities that are primarily personnel
ventional facilities, except that a hardened air
shelters (as opposed to operational facilities), per-
entrainment system (A ES) will be used to ex-
sonnel efficiency and comfort could be compro-
change air between the facility and the atmos-
mised to the extent of permitting somewhat higher
phere. The AES is discussed in TM 5-858-5.
effective and dry-bulb temperatures. With higher
ambient temperatures the maximum useful heat-
b. Design the transattack/postattack air-quality
sink temperature range and capacity could be in-
control system to include no fewer than the follow-
creased by raising the cooling water temperature,
ing capabilities:
for example, from 68F to 78F. However, the ap-
--Provide acceptable preattack availability.
parent advantage is illusory where the major heat
--Provide acceptable quality control of air-flow
load is the metabolic heat of personnel, since at
velocity, temperature, humidity, oxygen,
higher temperatures the percentage of total meta-
carbon dioxide, contaminants--as deline-
bolic heat rejected as water vapor (latent heat) in-
ated below.
creases rapidly and dehumidification requires low-
--Accommodate exercising preattack.
er coolant temperatures (50F or less).
c. Transattack/postattack ventilation systems
d. Where operating equipment is the important
that communcate with the atmosphere must pro-
consideration, air temperatures will be limited by
vide for removal of large dust loads and insidious
equipment cooling requirements. In general, the
chemical, biological, and radiological warfare
reliability of electronic and electrical power equip-
contaminants. This is an extremely difficult task
ment is inversely proportional to the air tempera-
that should be avoided by using a closed ventilation
ture. Battery-inverter systems, for example, are
system whenever possible.
prime candidates for closed-cycle power systems,
and the recommended operating temperature for
42. Air-flow velocity. Design the system for
inverter systems and storage temperature for
minimum circulation velocity of 50 ft/min in any
batteries is usually no higher than 75F. Inverter
part of the facility that is contaminated by carbon
system availability and battery cell life improve at
dioxide, water vapor, or toxic and combustible
lower ambient air temperatures.
gases and of 100 ft/min in areas normally occupied
by personnel. Substantially higher air velocities
e. For cooling facility air, use air-to-chilled
may be justified in some occupied locations to
water or air-to-refrigerant fan-coil units. To mini-
maintain required effective temperatures at higher
mize power demand and heat-sink requirements for
dry-bulb temperatures, without excessive demands
air cooling, specify liquid-to-liquid heat exchangers
for power to dehumidify the air.
to remove waste heat from equipment at the source
wherever possible.
43. Air temperature.
a. Temperature control in hardened facilities will
of the power systems as much as possible to mini-
typically require heat removal. Two prime consid-
mize heat generation. Where this is not feasible,
erations govern the establishment of design air
specify electrical heating rather than gas, to pre-
temperatures: personnel comfort and efficiency,
clude gaseous combustion products that would
and cooling requirements for air-cooled equipment.
need venting at further expense.
4-1
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