Section 20: Fire System Operation; Manual Signal Silence; Automatic Signal Silence (Bell Cut-Off); Signal Silence Inhibit Timer (Fire Silence Delay) - DSC PC4020 Installation Manual

S e c t i o n 2 0 : F i re S y s t e m O p e r a t i o n

20.1 Manual Signal Silence

Once the panel is in alarm and the alarm notification appli-
ances are active, entering a valid user code will silence the
alarm signals. If an LCD4521 keypad is used, pressing the
"Silence Bells" function key then entering a valid user code
will silence the signals. (see below for Valid User Code)
If the signal silence inhibit timer (Fire Silence Delay) is pro-
grammed, the user will be unable to silence the alarm noti-
fication appliances until the timer has expired. In this case,
the LCD display will show "SILENCE INHIBIT XX MIN"
to indicate how much time remains before silencing can be
done. This display will show for three seconds and the LCD
display will then return to the Auto-Scroll mode. Silencing
will not deactivate any output programmed as Fire Strobe.
Once the signals are silenced, the LCD Auto-Scroll mode
stops and the message "FIRE BELL HAS BEEN
SILENCED" is displayed. This message will remain until
any key is pressed. The "FIRE BELL HAS BEEN
SILENCED" message will return 30 seconds after the last
keypress.
Manual Silencing initiates a trouble condition by turning on
the keypad trouble LED and sounding the keypad buzzer.
The buzzer may be silenced by entering an access code.
If a Waterflow Alarm is present on the system silencing will
not be possible. Instead, the system will announce, "Silence
Inhibit. Waterflow Alarm." All Waterflow Zones must be
secured before the system can be silenced.

20.2 Automatic Signal Silence (Bell Cut-Off)

Ref #: [000200] Fire Timeout (default Y)
Ref #: [00020300] Bell Cut-Off (default 004 minutes)
The fire alarm notification appliances may be set to silence
automatically after a programmed time. The system is
default programmed to silence the notification appliances
four minutes after the last initiated fire alarm. If the Fire
Timeout option is disabled, the notification appliance can
only be silenced manually.
The Bell Cut-off timer begins upon the first fire alarm. Each
subsequent alarm will restart the timer.
If the alarm notification appliances are silenced automati-
cally, the Auto-Scroll feature will continue and will include
the following message: "FIRE BELLS HAVE BEEN
SILENCED." Outputs programmed as Fire Strobe will not
deactivate on Bell Cut-off.
NOTE: If the Fire Silence delay is programmed, the Bell Cut-
off time must be set for a time equal to or greater than the
Fire Silence delay time. This will ensure that the alarm noti-
fication appliances cannot be silenced manually or will not
silence automatically before the Fire Silence Delay time has
expired.
Automatic silencing initiates a trouble condition by turning
on the keypad trouble LED and sounding the keypad
buzzer. The buzzer may be silenced by entering an access
code.
20.3 Signal Silence Inhibit Timer (Fire Silence
Delay)
Ref #: [000203111] Fire Silence (default 000 minutes)
When it is required that the Alarm notification appliances
operate for a minimum period before they can be silenced,
program the Fire Silence Delay timer for that period. Man-
56
ual silencing will be inhibited for the programmed period
and if a user attempts to silence before the delay expires, the
LCD will display "SILENCE INHIBIT XX MIN" to indicate
how much time remains before manual silencing can be
done.
The Bell Cut-off timer must be disabled (Fire Timeout = N)
or set to a time equal to or greater than the Fire Silence
Delay time. This is to guarantee that the alarm notification
appliances will not silence automatically before the Fire
Silence Delay period.

20.4 Fire System Reset

Once the Fire notification appliances have been silenced
(manually or automatically), the fire system may be reset by
entering a valid user code. On an LCD4521 keypad, press-
ing the Fire reset function key then entering a valid user
code will reset the system. The "Fire Silence Delay" timer
will inhibit both manual silencing and reset until the delay
period expires.
When the system is reset, all latched fire functions within
the panel are restored and a Sensor Reset is initiated to
restore all 2- and 4-wire smoke detectors. If an alarm is
present at the end of the reset period, the panel will go into
alarm. The Auto-Verify Fire delay and Waterflow delay are
both in force after a system reset.
Fire Supervisory Off-Normal is a latched function and will
be restored on system reset.

20.5 Manual Sensor Reset ([*][7][2])

Ref #: [0100XX01] Com O/P2 Rq Cd (default N)
where XX = Partition (01 to 08)
The Sensor Reset function is designed so that the user can
manually reset latching smoke detectors by entering
[*][7][2]. In order for this feature to function, the detectors to
be reset must be connected to a programmable output
(SAUX+, PC4204/PC4204CXCF).
Program the output as "Command Output 2" (output
option #39). The output pulse time is default set at five sec-
onds. For instructions on output programming, see your
PC4020 Installation Manual, Section 11 "Programmable
Outputs."
RECOMMENDED: As a security measure, enable the Com
O/P2 Rq Cd partition toggle option. This will require that a
user enter a valid access code after entering [*][7][2] in
order to reset smoke detectors.

20.6 Subsequent Alarm Operation

If the alarm notification appliances have been silenced –
manually or automatically – and a subsequent fire alarm is
initiated, the following will occur:
• Audible and Visual notification appliances will activate
as programmed.
• Auto-verification is overridden for Auto Verify Fire
zones (alarms are instant).
• The Waterflow Delay is maintained for waterflow
zones.
• The Bell Cut-off timer, if used, will restart for a full tim-
ing period before automatic silencing.
• The Fire Silence Delay timer, if used, will NOT restart.
The silence inhibit period is not reinstated and silencing
can be done without any delay.