Operation
Calibration (
continued
)
l
Apply a 50% LEL gas concentration to the
sensor. The display will change from
“AC” to “CP” (figure 14) indicating that
the sensor is responding to the calibration
gas.
l
After one or two minutes the display will
change from “CP” to “CC” (figure 15)
indicating that the calibration is complete.
l
Remove the gas and wait for the unit to
return to normal operation. The display
will indicate less than 5% LEL and then
drop to “0” (figure 16).
l
The unit is now calibrated and the new
ZERO and SPAN values have been stored
in the non-volatile memory.
The Model S104 can be returned to normal
operation if the magnet is re-applied ninety
seconds after initiating the calibration se-
quence. If the Model S104 is placed in the
Calibration Mode and no gas is applied for six
minutes, the unit will revert to a Fault condi-
tion. Re-applying the magnet over the GMI
Logo will return the unit to the Calibration
Mode.
Procedure without digital display:
See figure 17 for LED flashing sequences.
l
If it is suspected that hydrocarbons are
present, it will be necessary to purge the
sensor environment with Zero Air. If
Zero Air is not available, cover the sensor
for about thirty seconds before applying
the calibration gas. Zero Air is air that is
hydrocarbon free.
l
Place the magnet next to the end of the
LED switch and hold it there until the
LED comes on steady.
l
Apply the calibration gas (50% LEL) and
wait for the LED to blink slowly (about
one or two minutes).
l
Remove the calibration gas and allow the
unit to see clean air.
l
The unit is now calibrated.
figure 14
figure 15
figure 16
figure 17
12
GENERAL MONITORS
Model S104
