4
Operation
Entering Parameters
Thermo Scientific
Multifuge 4KR
4-5
Run Time Pre-selection
5. Press the
key below the field run time.
1. Enter the desired value by pressing
up or down.
Up to 9 minutes 59 seconds the duration is given exactly to the second. After 10 minutes the
Explanation of RCF Value
The relative centrifugal force (RCF) is given as a multiple of the force of gravity g. It is a unitless
numerical value which is used to compare the separation or sedimentation capacity of various
devices, since it is independent of the type of device. Only the centrifuging radius and the speed
come into play in it:
r = centrifuging radius in cm
n = rotational speed in rpm
The maximum RCF value is related to the maximum radius of the tube opening.
Remember that this value is reduced depending on the tubes and adapters used.
This can be accounted for in the calculation above if required.
K-Factor
The k-factor is an information on the sedimentation capacity of a rotor. You can calculate the
required sedimentation time of each rotor with this formula:
t = sedimentation time in hours
K = clearing factor of the rotor (K-factor)
S
20,w
= Sedimentation factor for sample particles in water at 20 °C in Svedbergs
The k-factors given in this manual refer to:
r
max
= bucket bottom, (bottom of cavity of fixed angled rotors)
r
min
= bucket upper edge, (upper edge of cavity of fixed angled rotors)
Tubes which have various radii due to adapter or micro plate carriers the k-factor can be calculated
by using this formula:
RCF
11 18
,
n
1000
-------------
2
r
×
×
=
t
K
S
20,w
-----------
=
K
253000
(
)
n
r
max
r
min
---------
Speed
1000
-------------
2
÷
=
