MIL-HDBK-1003/3
The quantity of supply air shall also be calculated
using the cooling load calculation from equation (5) of
par. 5.3.2.
Add the extra dehumidification load of ventilation air
(due to lower room humidity) to the grand total heat load.
6.2.1.3
Sound Rating. In large central systems, one should
start with the noise limit that may be tolerated in the selected
room criteria and than work backwards through the system to the
fan. ASHRAE Handbook, HVAC Systems and Applications contains
noise guidance, and Army TM 5-805-4 gives noise criteria for
various room types. See Table 2-1 of Army TM 5-805-4 for indoor
noise criteria.
By isolating the fan on vibration pads, selecting a fan
in the efficient range, and utilizing the attenuation of
ductwork; the fan and air noise can be controlled. Refer to the
fan manufacturer's data sheet for fan noise values.
6.2.1.4
Static Pressure Requirement. To select a fan from the
fan manufacturer's fan curves, it becomes necessary to establish
the system static pressure requirement as well as the volume of
air delivery. With some types of packaged equipment, this rating
is called "external static pressure" and static pressure drops
required by coils, filters, etc., inside the equipment have
already been allowed. With central system fans, however, the
static pressure requirement in the entire system must be
established to select the total fan static pressure. Verify how
individual manufacturers rate their equipment and check their
curves and tables for system effects. Select fans so that they
will remain stable and not overload at any operating condition.
a) Pressure Drop of Air Handling Systems. Pressure
drop calculations of air handling systems shall include:
(1)
Outdoor air intake louvers,
(2)
Dampers,
(3)
Air filters (average between clean and dirty),
(4)
Heating coils,
(5)
Cooling coils (wet, dry, or sprayed
condition),
(6)
Moisture eliminators,
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