E8500 Instruction & Operations Manual
version 1.017
Page 9 of 49
D.
AUTOZERO ERRORS & BASIC TROUBLESHOOTING
AUTOZERO ERRORS
Channel
Possible Causes
Resolution
(Electrochemical
sensors)
CO
NO
NO
2
SO
2
H
2
S
O
2
Sensor has been
recently exposed to
gas and has not yet
returned to zero.
Purge for 10 minutes,
monitor sensor voltage,
and re-zero.
Battery was dead,
sensor has
destabilized.
Charge battery, wait up
to 24 hours for sensors
to stabilize, and re-zero.
Sensor cell is dead.
Call for a replacement.
T Stack
Thermocouple is not
connected
Check electrical
connections running to
the probe
Thermocouple was
hot
Probe tip should be cool
Stack Draft
Probe not connected
Draft voltage will be
high. Connect probe and
re-zero or ignore draft
readings.
Filters are dirty
Draft voltage will be low.
Check filters
Infrared CO-CO
2
-HC 00 No response from
infrared system
Autozero period must be
at least 60 seconds.
Zero the instrument
again.
Infrared CO-CO
2
-HC XX Infrared system is
reporting error code
XX
Infrared system may
need maintenance.
Velocity
Velocity probe is not
connected
Check probe and
connections.
Flow (low)
Filters are clogged
and/or wet
Replace filters as
needed
Flow (high)
Gas exhaust at
bottom of unit blocked
Unblock exhaust and
check all hoses
