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Sash Override/External Alarm Input
— A selection can be made
between a sash override input and external alarm input. The differences
between the inputs relates to the visual, audible, and remote indications
activated when the input is received by the monitor.
The sash override input can be connected to a sash position switch on
the fume hood to indicate that the sash has exceeded a given height and
a full alarm is sounded. When activated, the sash override puts the
monitor into alarm in the same manner as a low air flow condition. The
red LED lights, the horn sounds, the alarm relay is activated, and the
Override descriptor on the display illuminates.
The external alarm input is typically used for some external remote
event that may not warrant an alarm to the user, but is used rather as an
alert of a situation that may necessitate attention. When activated, the
external alarm input causes the horn on the monitor to sound
intermittently and illuminates the EXT descriptor on the display to
indicate that this is an external alarm. The EXT descriptor will remain
on until the external alarm input returns to an inactive state. Note that
this selection will
not
cause the alarm relay to activate.
NOTE:
The local alarm (steady horn) will always take precedence
over an external alarm event.
This Configuration Parameter selects the input and configures it for
open or closed contacts. Open indicates that opening the contacts
activates this alarm; closed indicates that closing the contacts activates
the alarm.
If the monitor is configured for closed contacts to activate the external
alarm, the display will show:
