ETL 1110-3-490
13 May 98
(1) Indoor Design Temperatures. Indoor dry and wet bulb design temperatures will be
determined in accordance with TM 5-810-1, associated references, and mission requirements.
(2) Outdoor Design Temperatures. The outdoor design temperature will determined in
accordance with TM 5-810-1 and associated references.
(3) Outside Air Occupant Ventilation Rate. The target outside air intake rate per occupant will
be 17 m3/hr (10 ft3/min) and, if necessary, a minimum outside intake rate of 8.5 m3/hr (5 ft3/min)
will be allowed. Normally, the filtered outside intake rate required to pressurize the TFA will
exceed the required occupant ventilation rate.
c. TFA Envelope Isolation and Control.
(1) Ductwork. Ductwork that serves the TFA during normal operation but is not required
during CP operations will be closed off and isolated by use of low-leakage dampers at the TFA
envelope. During CP operations, the TFA overpressure system will maintain pressure on the
isolation dampers under all conditions and thereby eliminate entrance of contaminated air into the
TFA. Isolation damper position indicators will be included to provide visual identification of the
open and closed positions. Additionally, the isolation damper position will be visually annunciated
at the system control panel. The leakage rating of the isolation dampers will be selected based on
an economical comparison of damper leakage and additional filtration capacity.
(2) Doors. Doors at the TFA envelope will be weather sealed to reduce the air leakage rate.
The door position will be monitored and visually annunciated at the system control panel.
B-10. CP Control System and Operational Requirements.
The CP control system will be located in the TFA, preferably in a utility room. The CP system will
be energized by one control panel switch that de-energizes other facility systems not required
during CP system operations. Examples of these systems are normal outside air fans, exhaust fans,
and recirculation fans that are in the building but outside the protected envelope. The control
system will monitor the position of all isolation dampers and doors by use of an annunciator light
at the control panel. All device positions; i.e., either open or closed, will be annunciated at the CP
control panel. A green indicator light will annunciate if the damper or door is in the correct
position during CP system operation. A red indicator light will annunciate if the damper or door is
not in the correct position or if a problem has occurred. The TFA overpressure, with reference to
the atmosphere, will be monitored and displayed on the CP control panel. To maintain the TFA
overpressure, the airlock doors must not be opened simultaneously.
B-8
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