The shelter shall maintain a positive pressure in all modes, i.e.
recirculation, cooling, and heating at all times. During an entry or
exit, the shelter low pressure alarm shall not activate when tested in
accordance with 188.8.131.52. During operation in the heating and cooling
modes (without entry or exit) the shelter and entrance pressures shall
fall within the limits specified in table I.
3.3.3 Entry and exits. A minimum of twelve entry and exits shall be
made during the four hour operating mode. When tested in accordance with
184.108.40.206 pressures in the shelter and entrance shall stabilize to the
values specified in 3.3.2 after an entry or exit. NOTE: An entry or
exit is defined as going from the outside through the entrance into the
shelter or going from the shelter through the entrance to the outside.
3.3.4 System leakage. With 160 cubic feet per minute (cfm) maximum of
make-up air being introduced into the system and with the shelter and
entrance maintaining at least minimum pressures (3.3.2), the purge-air
effluent, measured at the damper valve in the outside entrance door shall
be no less than 110 cm when tested in accordance with 220.127.116.11.
3.3.5 Entrance purge. The entrance shall be capable of purging
dioctylphthalate (DOP) to give a 1000 to 1 (3 log) reduction in 5.0 minutes
maximum when tested in accordance with 18.104.22.168.
3.3.6 Shelter purge. The shelter shell be capable of purging DOP
to give a 1000 to 1 (3 log) reduction in 60 minutes maximum when tested
in accordance with 4.3,3.1.
3.3.7 Noise. Noise inside the shelter shall be determined for vent,
cool and heat modes using applicable instrumentation and shall not
exceed the noise criterion curve NCA-60 of the ASHRAE Guide and Data
Book when tested in accordance with 22.214.171.124.
3.4.1 Preproduction and reliability qualification. Prior to the start
of regular production, a preproduction sample of the M51 shelter system
shall be produced in accordance with this specification for examination
(126.96.36.199), test (188.8.131.52), and reliability qualification (demonstration)
phase testing (184.108.40.206).
220.127.116.11 Reliability qualification (demonstration) phase. The M51
shelter system shall conform to the following Mean Time Between Failure
for both the overall system reliability and protection
reliability when tested as specified in 18.104.22.168 and evaluated for account-
able failures (3.4.3) in accordance with table I.