Short-Time Centrifugation; Relative Centrifugal Force (Rcf); Centrifugation Of Materials Or Mixtures Of Materials With A Density Higher Than 1.2 Kg/Dm - Hettich EBA 20 Mode D'emploi

EN
12.3

Short-time centrifugation

•
Set the desired speed with the keys
•
Keep the key pressed. The rotation indicator
0.
The first minute is counted up in seconds, and then the time is displayed in minutes.
When the time is displayed in minutes, a point flashes next to the number.
•
Release the key again to end the centrifugation run. The rotor runs down with the set brake step.
During the centrifugation run the rotor speed and the expired time are displayed.
13

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.
14

Centrifugation of materials or mixtures of materials with a density higher than 1.2 kg/dm

When centrifuging with maxim revolutions per minute the density of the materials or the material mixtures may not
3
exceed 1.2 kg/dm .
The speed must be reduced for materials or mixtures of materials with a higher density.
The permissible speed can be calculated using the following formula:
Reduced speed (n )
red
e.g.: maximum speed RPM 4000, density 1.6 kg/dm
1.2 kg/dm³
n = x 4000
red
1.6 kg/dm³
If in doubt you should obtain clarification from the manufacturer.
24/54
beneath the speed indicator.
appears while the rotor is turning. The time count starts from
2
⎛ ⎞
RPM
⎜ ⎟
= × ×
r 1,118
⎝ ⎠
1000
For more on the centrifugal radius see the chapter " Anhang/Appendix,
Rotoren und Zubehör/Rotors and accessories".
1.2
=
Greater density [kg/dm³]
3
RPM = 3464 RPM
RCF
⇒ =
RPM
×
r 1,118
x maximum speed [RPM]
×
1000
3