Thermo Electron SORVALL RC3BP, Operating Instructions Manual

Page: 26 / 64

3-9
RC3 BP™ Controls, Indicators, and Displays
most gradual rate, and each successive rate incorporating
incrementally more braking up to number 10. Selection of BRAKE
OFF will have an affect on SLOW STOP
(see the NOTE under
BRAKE OFF).
• BRAKE OFF deactivates normal deceleration braking for a
coasting stop from any specified speed (in rpm) between 6000
and 0. BRAKE OFF transition speed is set independently of set
run speed, and is not affected by changes to set run speed. If the
transition speed is set higher than the set run speed, at run
termination, the centrifuge will coast to a stop from set speed.
NOTE
If SLOW STOP and BRAKE OFF are both selected:
– If the BRAKE OFF transition speed is set to 500 rpm
or higher, the SLOW STOP selection will be ignored.
– If the BRAKE OFF transition speed is set below 500
rpm, the centrifuge will decelerate with full braking to
500, transition to the specified SLOW STOP rate,
then change to a coasting stop when the specified
BRAKE OFF transition speed is reached.
• CHANGE OVERTEMPERATURE LIMIT allows changing the
maximum allowable sample temperature to establish a new
overtemperature offset value. The centrifuge calculates the
difference between the set and the maximum temperatures, and
retains that value as an offset to apply to future runs, until it is
changed. The retained offset will apply to any normal (manual-
entry) runs as well as to any recalled program runs (specific
overtemperature limit settings cannot be saved in run programs).
See the EXAMPLE at left.
During a run, if the calculated sample temperature in the RUN
display goes above the maximum allowable sample temperature,
the run will terminate, a SAMPLE TEMPERATURE OVER LIMIT
message will appear in the SET display, and an alarm will
sound. This may indicate a condition requiring simple corrective
action, or it could indicate a refrigeration problem (see "SAMPLE
TEMPERATURE OVER LIMIT" on page 3-13).
Overtemperature termination is deactivated and a precool mode
begins if the RUN display temperature is more than 2
°
C over
the SET value when START is pressed, or when a temperature
change between programs occurs in a QC RUN or a STEP RUN.
A SAMPLE OVERTEMP – PRE-COOLING message will appear
and an alarm will sound. Pressing CLEAR removes the message
and shuts off the alarm, allowing the run to continue as a
precool run (P-COOL replaces DEG C as the field header in the
SET display during precool mode). A precool mode is automatic
during a QC RUN; the message and alarm are disabled, and the
program is repeated until temperature is within 2
°
of set.
EXAMPLE:
If you have a set temperature of 22
and set the maximum temperature to
24, an overtemperature alert will occur
if the calculated sample temperature
reaches 25. If the set temperature is
then changed to 4, the maximum
temperature setting will automatically
change to 6, based on the previously
calculated offset value.