Thermo Scientific SORVALL RC-5C PLUS, User Manual

Page: 35 / 55

Operation SORVALL ® Centrifuges
4-10
Test Run for Low Speed and Low
Temperature Operation
If the centrifuge is operated at a speed less than 2000 rpm and a
temperature 2
°
C or less, the refrigeration system may have difficulty
maintaining the indicated sample temperature within 1
°
C of the set
temperature. This condition may cause the sample to freeze;
therefore, when the speed and temperature are set below the values
given above, we recommend that you do a test run to determine a
temperature setting that will achieve the results you want and
prevent the sample from freezing. This test run procedure should
be used for every run where the rotor speed and sample temperature
are this low because each speed/temperature/rotor combination
may give different results.
1. Prepare two tubes or bottles of dispensable fluid and place them
in the rotor. Balance the rotor according to the instructions in the
rotor instruction manual.
NOTE
The dispensable fluid should have a freezing temperature
well below the desired sample temperature.
2. Set the RUN temperature switch to the desired sample
temperature.
3. Install the rotor in the centrifuge and run it for at least two hours
at the speed for which the temperature setting is being
determined.
4. Stop the centrifuge. Wait for the rotor to stop then immediately
open the chamber door and measure the actual sample
temperature using an immersible centigrade thermometer.
5. Adjust the RUN temperature switches upward or downward
according to the temperature differential between the measured
temperature and the set run temperature.
For example: If the measured sample temperature is -2
°
C and
the set run temperature is +2
°
C, there is a 4
°
C differential. To
obtain the +2
°
C sample temperature you should reset the set
RUN temperature switches to +6
°
C. (Setting the higher
temperature would prevent the sample from freezing.)