Eppendorf Galaxy CO2 Sensor - Manual (Page 82)

Equipment options
Galaxy
® 170 R/170 S CO
2
Incubators
English (EN)
82
12.5.6 Programming desired O
2
level
Program the required oxygen level in the PROG screen, following the onscreen instructions.
If you are running an O
2
level programmed between 0.1 - 0.9 %, you should know that the control system
is set to operate in the following way to minimize N
2
consumption after the glass door has been opened:
• The N
2
valve is switched on continuously until the O
2
level is within 0.1 % of setpoint.
• The CO
2
valve is then switched on to allow the CO
2
level to reach setpoint. If the O
2
level is above
setpoint 15 minutes after the N
2
valve has been switched off, it is switched back on for 40 seconds and
the CO
2
valve is switched on for 20 seconds. The CO
2
valve will then pulse until setpoint is reached.
• The process described above will repeat itself until the O
2
setpoint is reached.
• The same process will also repeat if the O
2
level rises above setpoint, and if the O
2
level should rise
toward 0.2 % above setpoint, the N
2
valve will open again continuously until the O
2
level returns to
setpoint.
• The CO
2
Auto-Zero, which would normally take place after a CO
2
alarm, will be cancelled to avoid the
introduction of additional O
2
into the chamber. For the same reason, we recommend canceling the
programmed CO
2
Auto-Zero.
12.5.7 Precautions
Under normal humidity conditions (95 - 99 % RH), the sensor is unaffected. If for any reason (such as a
large spill inside the chamber or the incubator being switched off while fully humidified) liquid condenses
around the sensor, the result may be restriction of gas flow and a low sensor signal. Should such
condensation appear on the chamber walls, normal operation can be easily restored by removing the
humidity tray, drying the chamber completely, and then running the incubator at 37 °C for one hour. This
will dry out the sensor. After the hour has elapsed, the humidity tray can be reinstalled and the incubator
humidified again.