Owner's manual

ISA-44RAL-OD / ISA-44RAH-OD ENMET Corporation
17
7.3 Oxygen Cell Replacement
The oxygen fuel cell has a six-month warranty. The average lifetime of the cell is twelve months. Replace the cell when
you can no longer adjust the oxygen gain potentiometer, outside on the front panel, so that the oxygen channel meter
reads 21%. An oxygen circuit that is in constant alarm is a good indication that the oxygen fuel cell is either expired or
grossly contaminated. See Figure 6
MATERIALS
§ screwdriver
PROCEDURE
1. Obtain a new oxygen cell, ENMET P/N 67013-008.
2. Do not open the sealed package as soon as you receive it. Wait until you are ready to use the cell. The cell is
packaged in nitrogen and begins its useful lifespan as soon as it comes into contact with oxygen.
3. Remove the two screws from the sensor housing cover.
4. Unpackage the new oxygen cell. Remove the "shorting clip" before installation. Your unit goes into alarm when
you disconnect the oxygen cell, if it isn't already in alarm. The absence of a signal from the oxygen cell makes the
circuitry react as if there is not enough oxygen in the air. Turn the operation switch to HORN OFF before
disconnecting the oxygen cell.
5. Carefully unplug the old oxygen cell from the printed circuit board. Install the new cell (it may be necessary to clip
off approximate 1/2 of the gold pins on the back of the new oxygen cell to make sure that the pins on the cell do not
puncture the gasket on the sensor housing). See Figure 6. The alarm should shut off immediately after the new
oxygen cell is plugged in. If it doesn't, you may have plugged in the oxygen cell backwards.
6. Replace the enclosure cover and screws.
7. Wait at least four hours for the oxygen cell to stabilize. Having been packaged in nitrogen, the cell must adjust to an
environment with oxygen in it. The meter reading will be much higher than normal until the cell stabilizes. Don't
bother adjusting the meter now; it will drift.
8. After at least four hours, verify the alarm point by adjusting the oxygen gain potentiometer (front panel of control
unit) down to trigger the alarm.
NOTE: If, after following these steps, you are unable to trigger an oxygen alarm by adjusting the oxygen gain, check
the voltage between the oxygen cell pins. It should be between .043 to .09 Vdc. If not, you have a defective
oxygen cell. If the oxygen cell voltage is good and the alarm still does not trigger, contact your area's
authorized ENMET service center or ENMET personnel directly.
9. Leave the meter set at 20.9%.
10. This procedure is now complete. Turn operation switch to OPERATE.
Top View (cover removed)
Side View(cover removed)
Side View (cut away)
Figure 6: Housing, Oxygen Cell and MOS Sensor
Cable to Instrument
Enclosure Cover
Oxygen Cell (Bottom View)
Center Pin (neg.)
Outside Pin (pos.)
MOS Sensor
and Clip
P C Board
O
2
Cell
and Clip
MOS Sensor & clip
O2 Cell w/clip & PCB