Proservo NMS5
52
Hauser
6.6
Calculation of Level and Densities
The section specifies the formula used by NMS5 to calculate levels and densities.
Figure. 56:
Calculation of Levels and Densities
Surface and Interface Levels
While the measured surface or interface level is constant, the displacer rests at the balancing position. The ten-
sion on the measuring wire is proportional to the displacer weight diminished by the buoyancy forces in both
layers:
A rise or fall of the level will increase or decrease the submerged volume. If this change exceeds the volume
tolerance set at matrix position GVH=345 "VOLUME TOLERANCE", then the
corresponding change will actuate the motor of the NMS5 till the balancing condition is fulfilled again.
Tank Bottom Level
For bottom level measurement, the balancing condition is defined as
Level
Formula
Liquid Level
T = W - V
вρ
u
Upper Surface
T = W - V
вρ
m - (V - V
в
)
ρ
u
Middle Surface
T = W - V
вρ
b - (V - V
в
)
ρ
m
Measuring Wire
Tension T
Gas
Density Negligible
Measured Displacer Weight W
Upper Liquid
Density
ȡX
Measured Displacer Weight Wu
Middle Liquid
Density
ȡP
Measured Displacer Weight Wm
Bottom Liquid
Density
ȡE
Measured Displacer Weight Wb
Balance
Volume V
B
Displacer
Volume V
6 Operation