Thermo Scientific 11174729, Instruction Manual

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Chapter 4
OPERATING PRINCIPALES
4-2 MR23i Thermo Fisher Scientific
The imbalance condition is displayed with the message “IMBA-
LANCE”. The display shows the actual speed and a TIME OUT
delay. The operator cannot open the lid until the rotor has stopped
spinning and he has pressed the ENTER key. When the motor
stops, opening and correctly loading the rotor allows the unit to be
restarted. The tolerated imbalance depends upon the rotor in use.
Carefully balance the sample load to avoid actuating the imbalance
detection system.
REFRIGERATION
SYSTEM
The Jouan MR23i is equipped with a CFC-free refrigeration
system which allows the rotor chamber temperature to be control-
led at a constant temperature. The refrigeration system injects cold
gas around the evaporator of the bowl in order to achieve the desi-
red temperature rapidly.
Avoid leaving the lid open in order to preserve good temperature
regulation and avoid the build-up of ice.
The temperature measurement of the air in the bowl is displayed
and the temperature is monitored by the microprocessor which
controls the cooling unit.
The operator can use a temperature compensation procedure so
that the sample temperature can be more accurately controlled
allowing for its original temperature.
Empirical tests by the user will enable him to know what air tempe-
rature to select compared to the normal temperature of the proto-
col. For example, suppose samples at 20°C need to be spun at
4°C.
It might be found with a protocol temperature (T) of 3°C that the
samples are cooled to 7°C. The temperature compensation (
T)
of the air in the bowl has to be set at 3°C (telling the control unit
that the result is 3°C too high) in order that the samples average
4°C during the run. The air will be maintained at 1°C. Of course,
this compensation is not possible if the refrigerant group is already
working at maximum power or if the run time is too short.
It is also possible to choose between refrigeration or not between
cycles in order to maintain the environment at the desired tempera-
ture. If active refrigeration is selected, this will only cease to ope-
rate if the lid is opened.
INTEGRATION
CENTRIFUGAL ACCELERATION
AND DURATION
Setting centrifugation parameters consists of determining the time
during which the sample is submitted to the selected centrifugal
acceleration. In practical terms, centrifugal acceleration is set in