KROHNE CORIMASS MFC 85 EN - Manual (Page 9)

9
4. General Concentration
4.1 Mixtures Of Two Immiscible Non Compressible Components
Immiscible means the two components do not mix or interact with each other. Typical
examples are oil/water emulsions or solid/liquid suspensions. For these cases, if you have V
S
volume of one component and V
C
of the other, then on mixing, the total volume V
T
is :
V
T
= V
S
+ V
C
Also for the masses :
M
T
= M
S
+ M
C
Also the densities of the components
ρ
S
,
ρ
C
and the mixture
ρ
M
are related by :
ρ
S
S
S
M
V
=
,
ρ
C
C
C
M
V
=
and
ρ
M
T
T
M
V
=
It can be shown that :
C
V
M C
S C
=
−
−
×
ρ ρ
ρ ρ
100% Equation 1
C
M
S
M
M C
S C
= ⋅
−
−
×
ρ
ρ
ρ ρ
ρ ρ
100% Equation 2
The figure below shows graphically these two equations for the case
ρ
S
=2.0 and
ρ
C
=1.0.
As can be seen, the C
V
curve is linear whilst the C
M
curve is not.
Concentration curves for Immiscible Mixtures
0.00%
10.00%
20.00%
30.00%
40.00%
50.00%
60.00%
70.00%
80.00%
90.00%
100.00%
1.000 1.200 1.400 1.600 1.800 2.000
Density (g/cc)
Conc. by Volume
Conc. by Mass
Ps = 2.0g/cm3
Pc = 1.0g/cm3
It is these two equations that are used in the MFC081/085’s general concentration algorithm.
ρ
M
is measured directly by the meter and
ρ
S
and
ρ
C
are known for the components in question.