- 32 -
7-3. Operation - Trouble Alarm
This unit can detect an internal failure. When an internal failure is detected, a trouble alarm will
activate (open collector is normally ON (closed position) and during a trouble alarm switches to
OFF (open position). The amber TROUBLE LED will start flashing, and the analog output will fall
to 0.6mA or less.
Self-resetting: When a problem is removed, the TROUBLE LED, open collector, and analog output
will automatically return to their normal positions/status.
Please refer to 10.
“Troubleshooting”, as well.
Internal failures include:
(1) Low flow rate
When a minimum flow rate is not present, the unit determines the flow rate is too low. The
FLOW is shown on the LCD and the spinning flow rate icon stops. The causes of a low flow
rate include: clogged filter element, clogged tubing, excessive negative pressure, worn
pump.
(2) Sensor fault
SENS. appears on the LCD in the following situations:
- the sensor
’s zero level output is extremely low.
- a broken sensor wire is detected. This applies to combustible gas sensor (CHS-7) only.
(3) Incorrect sensor installed
The data (e.g. target gas type, full scale value) from the last installed sensor has been
recorded by the gas detector. If a newly installed sensor unit does not match, the gas
detector will detect that an incorrect sensor unit is installed, and display the SENS. and
“ - - - -“ on its LCD. To use a newly installed sensor unit which does not match the previous
sensor type, press the COMM. button to renew the data.
(4) Broken pyrolyzer wire (when detector uses a pyrolyzer)
If a broken wire is detected, CONV. will appear on the LCD.
(5) No power
If the gas detector is not powered, all the LEDs will turn off and the detector will stop
operation.
(6) Blown fuse
If the fuse blows, causing the unit to lose power, then all the LEDs will turn off and the
detector will stop operation.
(7) Memory read error
When the internal memory cannot be read normally after powering-up,
“nG” will be shown
on the LCD.
