Copyright © 2002 demondo
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operation
digiflume™ contains a
capacitive level sensor. The fluid to be measured is part of the dielectric of a co-axial capacitor.
The relation between capacitance and fluid volume is linear. The volume of liquid in the barrel is calculated
in one of two basic modes:
In mode 1 the dielectric constant of the fluid is measured in an auxiliary
capacitance cell,
which is situated directly behind the input port. The dielectric properties are then used to
calculate the volume in the main barrel. In mode 3 the same calculation is performed, but applied only to the increase or
decrease of volume in the barrel since the last measurement. Mode 3 is chosen when the
dielectric constant of the liquid may vary over time.
In mode 1 or 3 the display shows on the upper line the calculated volume
and the instrument temperature. The temperature is measured by an RTD sensor in the base on the opposite side of the input port. On the lower line the relative dielectric constant of the fluid is displayed on the left
and a two digit number with instrument information on the right.
The first digit of this number is the mode of operation, the second shows the barrel size.
In mode 4 the volume in the barrel is calculated directly from calibration data; those are stored in non-volatile memory (EEPROM). Mode 4 can be used when very high precision is required. Data for up to eight different fluids can be retained in EEPROM. The display shows on the lower line the fluid which is presently being used. Mode 2 operates in the same way as mode 4 but with two fluids, for example water displacing oil:
More details on operation can be found in the manual.