MIL-PRF-24775A(SH)
f.
Scheduled maintenance shall not be required more than once per week. The average elapsed time per
week for scheduled maintenance shall not exceed 15 minutes.
3.9 Mean-time-to-repair (MTTR). The maintainability requirements of all shock grade A equipment expressed
as MTTR shall be 1.3 hours.
3.10 Human engineering. Human engineering design criteria and principles shall be applied in the design and
construction of the fan-coil unit to achieve safe, reliable, and effective performance by the operator and maintenance
personnel while optimizing personnel skill requirements. ASTM F1166 shall be utilized as a guideline in applying
human engineering design criteria for the fan-coil unit.
3.11 Design requirements. A fan-coil unit shall be a complete assembly, ready for shipboard installation, that
contains all components necessary for providing sufficient heating, cooling, and air recirculation required to satisfy
compartment environmental design conditions. Each unit shall consist of a fan(s) and a 2-speed fan motor(s), air
filter, thermal and acoustic insulation, thermostat, electrical control relays, and a chilled water-cooling coil.
Optional inlet and outlet grilles and electric heater are also installed, when specified. Type H units shall be designed
for horizontal mounting to overhead decking. Type V units shall be designed for vertical mounting to bulkheads.
Both types of fan-coil units shall be capable of being installed with or without ductwork. Bolt holes shown in
Figure 1 and Figure 2 shall be used for connection of ductwork or optional grilles. Electrical creepage and clearance
distances used in construction of fan-coil units shall be considered.
3.11.1 General design characteristics. General shipboard design characteristics shall be as follows:
a.
Power source quality - In accordance with MIL-STD-1399-300.
b.
Entering dry bulb (DB) temperatures of 70 degrees F (°F) minimum to 100 °F maximum.
c.
Entering wet bulb (WB) temperatures of 58 °F minimum to 82 °F maximum.
d.
Entering chilled water temperature of 45 °F.
3.11.2 Sizes. Sizes of fan-coil units shall be limited to those listed in Table I.
3.11.3 Capacity. Fan-coil unit capacity shall be as specified in Table I. Selection information shall be as
specified.
TABLE I. Fan-coil unit capacity. 1/
Rated values 2/
Nominal capacity range
(Wet cooling coil)
Fan-coil
Cooling 3/ (MBH)
External static
Heating (kW)
unit size
Capacity
Airflow
pressure
EDB (°F) 70 - 100
heater size
ft3/min
(MB)
(in. w.g.)
EWB (°F) 58 - 82
(Low, Medium, High)
1
145
0
5.85
2.78 - 12.86
1.2, 2.2, 3.3
2
240
0
9.69
4.63 - 21.03
1.2, 2.2, 3.3
3
350
0.25
15.28
7.27 - 34.39
1.75, 3.5, 5.25
4
530
0.25
22.89
10.98 - 50.06
2.0, 4.0, 6.0
5
690
0.25
30.50
14.66 - 66.01
2.0, 4.0, 6.0
6
950
1.0
39.91
18.94 - 90.44
3.0, 6.0, 9.0
7
1100
1.0
45.56
21.67 - 102.44
3.0, 6.0, 9.0
8
1650
1.0
72.92
34.80 - 161.35
3.0, 6.0, 9.0
7
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