Quantcast Shielded Enclosures

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MIL-HDBK-1012/1
observed daily to insure they are both operating.  If the fans are of a type
making observation difficult, then a failure alarm should be considered
d) Safety features.  Battery rooms shall comply with OSHA
regulation 1926.403, Battery Rooms and Battery Charging.
4.2.4.4
Shielded Enclosures.  HVAC systems for areas that require
electrical and/or acoustical shielding should be one of two types:
a)  Electrically shielded enclosures.  For these areas, supply and
return ducts penetrating the shield shall be provided with radio-frequency
(RF) cutoff cores at the penetration points.  Temperature and humidity control
sensors shall be located in the return air duct outside the enclosure rather
than the space itself to avoid filters in the control wiring.  Requirements
for backup, inside design temperatures and similar factors shall be as
indicated in the BESEP for the specific facility type.
b) Electrical/acoustical shielded enclosure. Air handlers within
the room should be considered to avoid large supply and return ducting.
Minimum sized fresh air supply/exhaust openings or ducts will still be
necessary and must have RF cutoff cores and acoustic attenuators. Temperature
and humidity controls can then be within the room and control wires need not
penetrate the shield.  This method requires only that power for the fan, plus
a few watts for control, penetrate the shield, and therefore limits the power
that must be filtered.  The air handler in the room may use direct expansion,
chilled water, steam or hot water coils supplied via piping from remote
heating and cooling units.  The advantage is that main power for these
functions need not enter the room, eliminating the need to filter it.  The
piping penetrating the shield must be metallic, must be bonded to the shield,
and must be long enough to ensure RF cutoff.
Plumbing.  Plumbing systems shall be in accordance with NAVFAC DM-
4.3
3.01, Plumbing Systems. Special requirements not covered by DM-3.01 are as
follows:
4.3.1
Battery Rooms.  UPS battery rooms and other spaces containing
electrolytic solution must be provided with emergency showers and eye wash
facilities, as specified in OSHA 1926.403, Battery Rooms and Battery Charging.
4.3.2
Shielded Enclosures.  Domestic water and other plumbing piping
penetrating the shield must be bonded to it to ensure RF cutoff.
4.3.3
Transportables.  Generally, the requirements of DM-3.01 do not
apply to the tactical type of transportable.
4.4
Fire Protection.  Design of fire protection and signaling systems
is covered by MIL-HDBK-1008 and MIL-HDBK-1190.  Fire protection signaling
systems are briefly discussed in Section 5 of this handbook.  The following
discussion is intended only to highlight data contained in the reference
documents which should be consulted for more detailed guidance.
4.4.1
Areas Not Containing Electronic Equipment.  Offices, classrooms and
similar spaces are usually sprinklered, especially if the building is of
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