Nellcor Oximax NPB-40 Operator's Manual page 22

Description of Controls, Indicators, and Symbols
Note: When the NPB-40 is turned on, a button press,
except the Power button, should result in either a
valid or an invalid key tone (refer to Description of
Audible Indicators on page 22). If the key pressed
fails to emit a tone, contact qualified service
personnel.
The Alarm Silence button. Press the Alarm Silence
button to silence audible alarms within 1.5 seconds after
the start of the alarm. If the Alarm Silence button is
pressed when no audible alarm is active, alarms during
the alarm silence duration will be silenced. In all cases,
the alarm silence shall time out after the selected alarm
silence duration, and auditory alarm capability is
reactivated.
Note: Alarms that occur throughout Power-On Self-Test
(POST) cannot be silenced.
Press and hold the Alarm Silence button for three
seconds to invoke the Alarm Silence Duration menu,
which allows the alarm silence interval to be adjusted
from 30, 60, 90, or 120 seconds or to OFF (alarms
disabled). See Set Alarm Silence Duration on page 54.
The Down Arrow button. Press the Down Arrow button
to sequentially decrease the parameter under adjustment
by one decrement. Press and hold the Down Arrow
button for more than three seconds may cause the
decrement to repeat.
Press the Down Arrow button during normal operation
to decrease the pulse beep volume.
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