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REMOTE INTELLIGENT SENSOR - AREA MONITOR
Instruction 2772-0803 Page 3-3
Flashing
This symbol shows that sampling vacuum
has dropped. The cause could be a pump
failure or an air leak.
Optics
Icon warns that the light level is not
acceptable. In addition, the affected
channel is shown by a 1 or 2, or both.
NOTE: This will occur if the tape gate is
opened, an external light source enters the
sampling input FET tube(s), the tape breaks,
runs out, or, if the cassette is changed
without first going into the TEST Mode.
Door Open
This icon is displayed when the system door
is open. It is also shown if the ‘door closed
switch is incorrectly adjusted or if the door
securing screws are not tight, be careful
not to over tighten them! The switch
adjustment procedure is detailed in Sec-
tion 4.7.
3.8 SYSTEM ALARMS
The standard RIS provides displays of gas and
fault alarms, and a combined ‘relay’ output. Basic
systems have one gas alarm set point with a default
value established by the system software. The alarm
set point is also user adjustable through the RIS
keyboard so that it can be set to an appropriate local
value. Set point adjustment is covered in Section
2.8.2.3. The default values are shown in the Table #1.
A fault alarm is initiated by any one of several
monitored parameters. Appropriate icons are shown
on the display when a fault is detected.
3.8.1 GAS ALARM. When a gas concentration
value above the alarm set point is detected, the
‘flashing bells’ icon provides visual warning. Simul-
taneously the combined gas alarm/fault relay opens.
Both warnings, visual and relay signal, remains
active until a gas concentration lower than the set
point is measured over a complete sampling cycle
(normally 4 min.). This ensures that small varia-
tions around the set point do not cause intermittent
alarm operation.
3.8.3 ADDITIONAL GAS ALARM SET POINT.
When the Relay alarm Option is installed, a second
alarm level set point is provided. This second set
point is also user adjustable. In this case there are
three active relays, one for each alarm level, and one
for fault indication.
SYSTEM OK icon confirms the system is
operating normally.
NUMERICAL VALUE (in ppb or ppm)
alternates with % value of remaining cassette
life. When cassette is new the display reads
99%. As the tape is used, the numerical value
reduces in proportion.
NOTE: If the system is turned off and then
on at SW1, or if the tape reset button is
used, the tape counter is reset to 99%. This
occurs despite the actual tape remaining.
3.7.2 SYSTEM NORMAL, GAS CONCENTRA-
TION ABOVE THE ALARM THRESHOLD.
Besides the SYSTEM OK and the NUMERICAL
VALUE of the measured concentration, a ‘FLASH-
ING BELLS’ icon is shown across the top of the
display. This provides a strong visual warning that
a Gas Alarm is present. The display is maintained
during the period that the threshold level is ex-
ceeded and until a complete sample period has
passed where the concentration falls below the alarm
level.
3.7.3 OVER RANGE ALARM. When the moni-
tored concentration exceed the system range, the
‘flashing bells’ icon is accompanied by the numerical
readout displaying 9999 (ppb models) or 99.99 (ppm
models).
3.7.4 SYSTEM FAULT. When self diagnostics
detect a fault condition, the SYSTEM OK icon is
turned off and one or more fault icons are dis-
played. Icons and their meaning are as follows:
Constant
This symbol shows that the input supply
has failed, or is not connected, and the
system is operating from the internal
back-up battery.
Flashing
Shows that the back-up battery charge is
low. This could occur with long interruption
of input power. It can also warn that the
battery is not maintaining an adequate
charge during NORMAL operation.
Constant
Warns that the cassette has run out of
tape, or the tape has broken, or the tape
gate has been left open.