Cooling (Only In Centrifuges With Cooling); Standby-Cooling; Pre-Cooling The Rotor; Relative Centrifugal Force (Rcf) - Hettich UNIVERSAL 320 Mode D'emploi

EN
20

Cooling (only in centrifuges with cooling)

The temperature set-point can be adjusted from -20°C to +40°C. The lowest obtainable temperature is dependent on
the rotor (see Chapter "Anhang/Appendix, Rotoren und Zubehör/Rotors and accessories").
20.1

Standby-cooling

With rotor standstill and closed lid the centrifugal chamber is cooled to the pre-selected temperature. The
temperature set-point is shown in the display.
Standby cooling will be subject to a timed delay after a centrifuge run and the display will show
OEFFNEN. The delay time can be pre-set in 1minute steps from 1 to 5 minutes. It is pre-set to 1 minute.
With the rotor standing still and the cover open the delay time can be set as follows:
•
Hold down the key for 8 seconds.
After 8 seconds, t/min = X appears in the display.
•
Use the rotary button
•
Press the key
START / IMPULS
As confirmation, ∗∗∗ ok ∗∗∗ will be displayed for a short period.
To leave the delay time display press the key
20.2

Pre-cooling the rotor

•
Press the key . The LED in the button
•
Press the button
OPEN / STOP
brake step is displayed.
During the centrifugation run the rotational speed of the rotor or the subsequently resulting RCF value, the sample
temperature and the expired time will be displayed.
The pre-cooling speed can be adjusted in decadic steps from 500 RPM to the max RPM of the rotor. It is pre-
adjusted to 2800 RPM.
When the rotor is stationary and the lid open the pre-cooling speed can be set in the following manner:
•
Hold down the key for 8 seconds.
After 8 seconds, t/min = X appears in the display.
•
Press the key once again.
The set pre-cooling RPM - RPM = XXXX will be displayed.
•
Set the desired pre-cooling speed using the knob .
•
Press the key
START / IMPULS
As confirmation, ∗∗∗ ok ∗∗∗ will be displayed for a short period.
To leave the pre-cooling RPM display press the key
21

Relative centrifugal force (RCF)

The relative centrifugal force (RCF) is given as a multiple of the acceleration of gravity (g). It is a unit-free value and
serves to compare the separation and sedimentation performance.
These values are calculated using the formula below:
RCF
RCF = relative centrifugal force
RPM = rotational speed (revolutions per minute)
r = centrifugal radius in mm = distance from the centre of the turning axis to the bottom of the centrifuge.
The relative centrifugal force (RCF) stands in relation to the revolutions per minute and the centrifugal
radius.
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to set the delay time.
in order to store the setting.
OPEN / STOP
START / IMPULS
to end the pre-cooling. The run-down is effected with the selected brake step. The
in order to store the setting.
OPEN / STOP
2
⎛ ⎞
RPM
⎜ ⎟
= × ×
r 1,118
⎝ ⎠
1000
For more on the centrifugal radius see the chapter " Anhang/Appendix,
Rotoren und Zubehör/Rotors and accessories".
or do not press any key for a period of 8 seconds.
lights up for as long as the rotor turns.
or do not press any key for a period of 8 seconds.
RCF
⇒ =
RPM
×
r 1,118
OPEN
×
1000