7. ALARMS - The growth chamber has high and low alarms. There are
settable delay timers and alarm band associated with these alarms. The
high and low timers provide a delay before either alarm will go off if
the chamber temperature has deviated from the setpoint temperature
by the amount set in the alarm band. These time delays and alarm
band are used in the control to distinguish between door openings and
real alarms. The following is an example of this:
The growth chamber is controlling at 40.0°C and the low delay timer
is set for 2 minutes and the alarm band is set for 1°. Now the door is
opened. Most likely, the temperature will begin to drop.
If the door is not closed and the control senses a temperature of 39°C
or less after 2 minutes, the low alarm temperature will go off along
with the compressor. This is not a real alarm failure. If the door is left
open long enough for this to occur, then the door must be closed
sooner so the growth chamber can recover in time. Alternately, the
delay times can be set for a longer period of time, or the alarm band
can be increased.
To adjust the delay timers and the alarm band, follow these instructions:
A. Press and hold the up or down arrow keys and then press the
ENTER key and the displays will change to the following:
Use the up arrow key to select 01 and then press ENTER. The
displays will change to the following:
A number other than 01 might be shown. This is the delay time
setting, in minutes, for the high alarm. Use the up or down arrow
keys to select your time value and press ENTER and the displays
will change to the following:
3-8
Plant Growth Chamber
Thermo Scientific
Section 3
Operation and Calibration
