RC12
BP™
Controls, Indicators, and Displays
3-11
• CHANGE UNDERTEMPERATURE LIMIT allows changing
the minimum allowable sample temperature to establish a new
undertemperature offset value. The centrifuge calculates the
difference between the set and the minimum 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
undertemperature 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 below the minimum allowable sample temperature,
a SAMPLE TEMPERATURE UNDER 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 UNDER LIMIT" on page 3-16).
This undertemperature alert is not activated and a preheat mode
begins if the RUN display temperature is more than 2°C under the
SET value when START is pressed, or when a temperature change
between programs occurs in a STEP RUN. In each case, a SAMPLE
UNDERTEMP – PRE-HEATING 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 preheat run (P-HEAT
replaces DEG C as the field header in the SET display during preheat
mode). A preheat 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.
• STEP RUN allows the linking-together of up to three sets of
programmed run parameters to automatically perform step run
protocols. When step run is selected, the specified programs must
specify the same rotor at similar temperatures. Step runs can be
saved to program memory (program numbers 10-15) for simple
recall in future use (see SAVE RUN below).
• SAVE RUN allows pre-programming of up to 15 different sets of
run parameters (9 standard runs, and 6 step runs) for simple recall
and error-free run reproducibility. In addition to basic parameters,
all option selections and settings (excluding rotor name,
overtemperature limit, and undertemperature limit) will also be
saved to program memory. To eliminate inadvertent loss of
existing programs, the save run sequence alerts users before
overwriting. The convenient RECALL key allows browsing
through existing programs for selection or reference.
NOTE If you plan to use the QC RUN feature, specific guidelines
should be considered when saving parameters to memory
(see QC RUN on page 3-8).
EXAMPLE:
If you have a set temperature of 22
and set the minimum temperature to
20, an undertemperature alert will
occur if the calculated sample
temperature goes down to 19. If the
set temperature is then changed to 4,
the minimum temperature setting will
automatically change to 2, based on
the previously established offset value.
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