ETL 1110-3-498
24 Feb 99
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.
C-10. Collective Protection 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.
C-11. Operation and Maintenance.
a. CP System Operational Testing. Standby CP systems should be tested once each month
to ensure that they are in good operating condition. For continuously operated systems, periodic
system monitoring should be performed to ensure the CP system is operating properly.
b. Filter System. In addition to the manufacturer's recommended maintenance requirements,
the following filter replacement and testing requirements should be performed.
(1) High-Efficiency Particulate Air (HEPA) Filter. The initial resistance of the HEPA filter is
typically 250 Pa (1.0 inch wg). The HEPA filter should be replaced when it is loaded and the static
pressure differential reaches about 750 Pa (3.0 inches wg). The HEPA filter pressure drop will be
monitored at the CP system control panel with annunciation when the dirty filter pressure drop is
reached. The HEPA filter will be mechanically leak tested after filter replacement.
(2) Adsorption Filter. The adsorber filter should be replaced as required in FM 3-4 and
mechanical leak tested with a test gas after filter replacement.
(3) Airflow Testing. The filtration system airflow rate should be periodically tested and re-
balanced as necessary to maintain the design airflow rate. The filtration system should also be
airflow tested after prolonged use. A HEPA filter without a prefilter could be fully loaded after 9
months of continuous use. Utilizing a prefilter will extend the life of the HEPA filter to about 2
years of continuous use.
C-6
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