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Subsequent alarms
BAS-APG001-EN 101
Subsequent alarms
(UL 864: 49.8)
When multiple input signals are received from more than one smoke zone
to initiate different automatic smoke-control sequence(s), the smoke-
control system shall continue automatic operation in the mode
determined by the first signal received.
Once a floor-based smoke alarm is activated, the system will react as if
that is the only alarm and will ignore all subsequent alarms, The supply,
return and stair shaft smoke alarms are still allowed to affect the supply,
return and stair shaft supply fans. Any reaction can be overridden at the
smoke control panel.
To ignore all subsequent floor alarms, the program fragment in Figure 53
on page 102 has been tested and works correctly. Once an alarm is
triggered by any floor-based smoke alarm, it will be the only smoke alarm
reaction allowed. When the first alarm is received, it triggers two events;
it writes the floor of the smoke alarm to analog variable 1 and sets a
binary variable to hold the output at that value. That binary variable is
held until all alarms are cleared by the fire smoke control system.
Table 28. Operational priority
Current state of system
Manual
override
Automatic
smoke alarm
System self-test Panel lamp test
HVAC
(nondedicated)
Next state of system
Manual override
N/A Actuator is
overridden.
System self-test
ends.
Panel lamp test
can continue.
Actuator is
overridden.
Automatic
smoke alarm
Affects all non-
overridden
actuators.
N/A System self-test
ends.
Panel lamp test
ends.
HVAC system
operation is
completely
suspended.
Only smoke
purge operation
is allowed.
System self-test
System self-test
is not allowed
to start.
System self-test
is not allowed
to start.
N/A Allowed. No
change.
System self-test
not used.
Panel lamp test
Panel lamp test
is allowed to
start.
Panel lamp test
is not allowed
to start.
Panel lamp test
is allowed to
start.
N/A Panel lamp test
is allowed to
start.
HVAC
(nondedicated)
HVAC system
running, but
overridden
actuator will be
affected.
HVAC opera-
tion is not
allowed to start.
System self-test
not used.
HVAC opera-
tion continues.
N/A