Eppendorf R Series 48R CO2 Incubator - Manual (Page 58)

58
CO48R-0050 Š Galaxy R Series 48 R Personal Size CO
2
Incubator User’s Guide
8.6.4 Alarms
The alarm levels are set automatically to ± 0.5% above and below the
programmed value, but these points can be altered in the
ALARM screen. In
addition, the rearming of the alarm can be delayed until the Programmed Value
is achieved by selecting the relevant option in the
ALARM screen.
For example, it is possible at low oxygen levels that the CO
2
and O
2
levels
might not fully recover within the Alarm Limits after the 15-minute DELAY IN
ARMING AFTER DOOR OPENING period has elapsed, so this time period can be
increased in the ALARM screen to suit individual circumstances.
8.6.5 Referencing to Atmosphere
To reference the oxygen sensor to atmospheric oxygen levels, see Section 8.5.4.
8.6.6 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
AutoZero, 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
AutoZero.