Relative Centrifugal Force (Rcf); Centrifugation Of Materials Or Mixtures Of Materials With A Density Higher Than 1.2 Kg/Dm; Emergency Release - Hettich ROTOLAVIT Mode D'emploi

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.
22

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
In the exceptional case that the maximum loading indicated on the hanger is exceeded, the speed must also be
reduced.
The permissible speed can be calculated using the following formula:
Reduced speed (n )
red
e.g.: maximum speed RPM 4000, maximum load 300 g, actual load 350 g
300 g
n = x 4000 RPM
red
350 g
If in doubt you should obtain clarification from the manufacturer.
23

Emergency release

The lid cannot be opened during power failure. An emergency release has to be executed by hand.
For emergency release disconnect the centrifuge from the mains.
Open the lid only during rotor standstill.
Only the plastic release pin provided may be used for emergency release.
See figure on page 2.
•
Switch off the mains switch (switch position "0").
•
Look through the window in the lid to be sure that the rotor has come to a standstill.
•
Insert the release pin (see scope of supply) horizontally into the hole (Fig. 1, A). Push the unlocking pin in until
the handle can be lifted when the pin is pressed down.
•
Open the lid.
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
maximum load [g]
= x maximum
actual load [g]
= 3703 RPM
RCF
⇒ =
RPM
×
r 1,118
x maximum speed [RPM]
speed [RPM]
EN
×
1000
3
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