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CDE-30 Series
Lab Conductivity Cells
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Model Constant Temp. Type Application
CDE-30- 01 122 x 11.75 K=0.1cm 0 to 100 ºC Platinum
Pl ates
CDE-30 -1 133 x 11.75 K =1 cm 0 to 1 00 º C Platin um G ener al u se
Disc
CDE-30- 10 119 x 11.75 K=10 cm 0 to 100 ºC Plat inum
Ring
CDE-30- 01S 107 x 12.00 K=0.1 cm 0 to 100 ºC
h x ø (mm )
Low Concentration
solutions
-1
-1
-1
-1
P aint and S ugar
Industries
Con cen t rat ed
Solutio ns
St ainle ss St ee l
Application Connectors
Connectors
Conductivity Cells, are supplied with PA Connectors
(Standard).
Service and Maintenance :
1 - For storage purpose, the cell must be kept in
distilled water.
2 - After every reading, the cell must be cleaned. For
cleaning, use a syringe filled with distilled water,
injecting it through the holes located on the cell
side, or dip it in a water solution made of detergent in
a proportion of 1:1, for 30 minutes. Then rinse it
with distilled water before using it.
3 - Never touch the Cell Electrodes, they contain Black
platinum that with a minimum contact with a solid
surface, will cause serious damages.
4 - When not in use, leave the cell always dip into
deionized water.
5 - For a better cleaning, when the cell is really dirty,
dip the cell in a water / alcohol solution in a
proportion of 1:1at 50 ºC for 15 minutes. Be
Careful, leave the cell to cool down, as any thermal
shock will cause the glass to break.
6 - For Platinum Cells, do not attempt to perform any
mechanical cleaning and do not touch the Platinum
Cells. In case the boards are bended, replace the
Cell immediately. If the Cell present cracks or is
broken, replace it immediately.
7 - For Stainless Steel Cells, the cleaning must be
performed using a sample solvent. Proceed by
removing the SS protection, located in lower
portion of the cell.
.
4
When a Cell is replaced under warranty, the new warranty will start
counting from Date Code of the new replacement cell. This
warranty does not cover any shipping charges, damages to Cell
body, caused by eventual contaminations or mishandle.
Instruction Manual
Conductivity Cells
CDE-30 Series
M.4505/0908
Page 4
Conductivity Cells and Parts
A
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(*) Consult dimensions
at appliction table
Models:
A - CDE-30-01 - Platinum Board Cell, constant K=0.1 cm
B - CDE-30-1 - Platinum Disc Cell, constant K=1 cm
C - CDE-30-10 - Platinum Ring Cell, constant K=10 cm
D - CDE-30-01S - Stainless Steel Cell, constant K=0.1 cm
Characteristics:
1-Low Noise Cable: assures stable Readings.
2-Polypropylene Cap: chemically aggressiveness resistant.
3-Glass Body: chemically inert.
4-Platinum Element (boards, discs or rings).
5-Transfluency Holes: for sample flowing
6-Transportation Cap: contains distilled water for transport or
storage.
7-Polypropylene Body.
8-Stainless Steel Protection: removable for a better cleaning.
9 - Sample Opening.
10 - Temperature Sensor location.
Definitions Conductivity Cells
DEFINITIONS:
Electrolytic Conductivity, also known as Specific Conductance, is the
solution capacity to conduct electrical current.
Electrical current conductance in electrolyte solutions differ from the one in
metals. In metals, the electrical current is composed basically by "free
electrons", in liquids the conductance is done by ions.
Specific Conductance results from the sum of contributions of all present
ions. But, the transported current fraction depends on relative concentration
and the freedom to move in the sample, where we can conclude that
specific conductance of an electrolyte varies with concentration of present
ions.
Specific Conductance is defined as reciprocal of Specific Resistance. In
unit terms, Resistance is expressed in Ohm/cm that will have a reciprocal as
Conductivity expressed in Mho/cm, also known as Siemens /cm.
Normally the submultiples are used: µS = 0,000001S and mS = 0,001S.
Conductance measure requires use of alternate current in order to minimize
the electrosis effect, that alters the solution composition. The current
frequency, in order to optimize the readings, must be situated within certain
limits.
Temperature Compensation and Coefficient
Conductivity values obtained on readings will depend on Temperature. This
relation between Conductivity / Temperature is linear, but strongly
influenced by solution natures. In general, the relation Conductivity /
Temperature, is expressed by a coefficient related specifically to each
ionized substance, that could vary between 0,5% to 10% per °C. Because
of this big variation, the user can observe that two Conductivity
measurements, of same function during measurements, will only differ by
some degrees (°C).
In order to guarantee correct measurement values, the first alternative
would be to perform readings at a constant temperature (thermostat
regulated at 25°C), method not very practical, but correct! Another
alternative would be to automatically compensate all readings based on a
reference temperature fixed at 25°C (ASTM Standard).
Inorganic Salt Solutions such as Chlorides, Nitrates, Sulfides, etc..., Are
good electrical current conductors. Organic substances such as Phenol,
Alcohol, Oils etc... Are the opposite, they are bad conductors.
So, when a reading of a solution indicates low conductivity value, that can
mean "Low Inorganic Concentration", even with a high Concentration. In
practice, it is introduced the concept of Total Dissolved Solids (T.D.S.)
That, refers only to inorganic components.
CONDUCTIVITY CELLS:
Conductivity Cells are composed typically of two boards or two
concentric cylinders (electrodes) with a well known geometry. The gap
between the boards will create a solution column, so the measurement
is independent from the total solution volume.
The geometry type used will be related to the solution concentration,
varying the distance or the boards section.
The relation "distance between platinum boards" over "section" will
determine the CELL CONSTANT (K = 1/cm).
In order to obtain good results it is necessary to choose the specific cell
for the desired application. Three factors are very important in order to
make the selection: Electrical, Mechanical and Chemical.
Electrical
When reading an electrolyte of high resistance caused by the lower
ions presence, a higher sensibility will be obtained with bigger
electrodes and with a small distance between them. Consequently user
must decrease capacitive reactance of the cell solution system,
increasing the frequency tension supplied by the equipment.
It is necessary to invert when the electrolyte is very concentrated:
smaller electrodes and with bigger distance in order to avoid saturation
and the polarization effect of the electrodes.
Which means, the cell will have a low "K", for low conductivity
electrolytes and a high "K", for high conductivity, considering that the
equipment must offer automatic exchange of the adequate frequency.
Mechanical
These are significant factors: pressure, temperature, flow speed and
solid suspension presence. Only when all these factors are considered,
the performance achieved will be considered satisfactory with a
minimum maintenance.
When the system’s temperature and pressure are higher than the
specified values, user must install a cooling system, with a valve,
before cell contact.
But, in places where the speed is very low, user must generate an
increase for the solution exchange. Solids presence will influence,
caused by the obstruction that they can cause to electrodes or even a
super-conductance (in metal cases).
Chemical
It is necessary to consider the aggressiveness and clogging of the
electrodes, that will determine the geometry, altering the constant
value.
In this cases, electrodes must be resistant to chemical aggressiveness
And be cleaned periodically.
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M-4505/0908
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