HIQUEL GmbH
Page 1
Author:
Peter Reiter
File:
HIQUEL_AppNote_TCL_1_E_R0100.doc
Translator: Markus Rindler
Date:
05.07.2004 12:56
TCL/PCL application instruction
Function
For supervising and/or controlling fill factors electronic level indicators/controls are required.
Our products with the following type designations represent such devices: TCL, PCL and
TCL3. Because of simplicity reasons, all these devices in this document are designated as
level controls. In the case of differences between the devices we will deal in a separated
manner with it.
Operating range
The application of the level control requires the fulfilment of the following:
•
The liquid you want to measure must be conductive.
•
The liquid you want to measure must not be flammable.
•
The liquid you want to measure must have its conductivity within the available
measuring range.
•
Make sure that the sensor cabling is placed within a shielded cable away from AC
cabling or engine cabling.
Conductive liquids
Resistor calculation
The calculation of the resistance of the medium is possible. For this, the size of the
electrodes must be known.
A
d
p
c
R
*
*
1
=
A =
Size of the electrodes [cm³]
d =
Gap of the electrodes [cm]
c =
Concentration
[val/cm³]
p =
equivalent conductivity [Scm²/val]
An equivalent means the amount of molecules of the liquid. There is one positive molecule
and one negative. For example, one molecule NaCl means Na
+
+ CL
-
the equivalent in this
case is 1. One molecule CaCl
2
means Ca
++
+ 2CL
-
the equivalent is ½.
Usually the size of the electrodes is not measured, but the d/A ratio is acquired when
measuring the resistance of a cell with a defined concentration and a known equivalent
conductivity. In some cases the cell constant will be necessary for measuring with the level
control.