LaMotte CDS 5000 User Manual
Instruction Manual For
L
M
o
tt
DIGITAL DISPLAY
CDS 5000
CONDUCTIVITY/TDS
.5
.6
.7
.8
.9
uS
ppm
mS
ppt
°C
OFF
SLOPE
CONDUCTIVITY
TDS
Controls Used
To Calibrate
Light
Indicates
Currently
Active Mode
Press Button
To Select
Operating
Mode
2
CDS 5000
L
Mott
CONDUCTIVITY/TDS METER
CODE 1752-01
TABLE OF CONTENTS
Conductivity.......................................................................................... 4
Meter Basics ........................................................................................... 5
Meter Specifications............................................................................... 6
Calibrating ............................................................................................. 7
Testing Water......................................................................................... 8
Testing Salinity ...................................................................................... 9
Testing Soil........................................................................................... 12
Maintaining the Meter......................................................................... 13
Warranty Information .......................................................................... 15
3
CONDUCTIVITY
Conductivity is defined as the ability of a solution to conduct an electrical
current, or the reciprocal of the solution’s ability to resist the current. This
current is conducted by electrically charged particles called ions, which
are present in almost all solutions. Different solutions have different kinds
and amounts of ions: distilled water has very few ions, and therefore a low
conductivity, while sea water has a large number of ions, and a high
conductivity.
Although a conductivity reading provides an overall measurement of the
ionic content of a solution, it is not possible to distinguish the specific
amounts of individual ions. For this reason, conductivity is often used to
measure the total dissolved solids (TDS) of a solution. TDS is defined as
the amount of solids which will pass through a 45 micron filter. Rather
than filtering a solution, the TDS can be estimated by multiplying the
conductivity measurement by a predetermined factor. This factor, which is
determined gravimetrically, will fall between 0.55 and 0.9; 0.7 is a
commonly used factor.
The conductivity measurement can also be used to estimate the salinity of
water, or the total amount of all salts dissolved in the water. Typically, the
conductivity reading is converted to salinity using charts, such as the one
found on page 10. These charts are based on water containing the same
amount and proportion of ions as standard seawater, so this form of
measurement is most effective for low concentrations and dilutions of
seawater.
Conductivity is measured in microsiemens per centimeter (msiemens/cm).
Siemens are also called mhos. In waters of higher conductivity,
msiemens/cm may be mul million. Therefore, using the information
discussed above:
msiemens/cm x 0.7 = ppm TDS
Salinity is usually measured in parts per thousand (ppt). The chart on page
10can be used to convert conductivity readings to salinity.
Because it is a quick, reliable, and inexpensive way of monitoring the
ionic content of a solution, conductivity measurements are widely used in
many areas of water testing, from environmental monitoring to municipal
water supplies to many industrial applications.
4
METER BASICS
Conductivity is measured using a probe which contains two electrodes,
separated by a fixed distance. When a voltage is applied from the meter
across the electrodes, the ions in solution conduct a current, which flows
between the electrodes. The greater the concentration of ions in the
solution, the larger the current generated and the higher the conductivity.
Likewise, the smaller the concentration of ions, the lower the
conductivity. The meter converts the current measured to a conductivity
reading.
Over time the electrodes may become dirty or fouled with contaminants
from the sample. For specific probe cleaning instructions for the CDS
5000 see Maintaining The Meter on page 13.
Conductivity measurements are very dependent on temperature. The
ability of the ions to move through the solution, and conduct the current,
is related to the temperature of the solution. As the temperature rises, the
ions move more quickly through the solution, increasing the conductivity;
likewise as the temperature decreases the ions move more slowly and the
conductivity decreases. Since the conductivity of the same solution can
change by as much as 2%/°C, accurate temperature measurements must
be made simultaneously to the conductivity reading. The CDS 5000
includes a temperature probe to measure the temperature.
To make conductivity readings taken at different times and places
comparable, measurements are often converted to what the conductivity
of the solution would be at 25°C. The CDS 5000 automatically makes this
conversion before providing a final reading.
5
METER SPECIFICATIONS
Range 1-199.9 mS/cm
200-1999 mS/cm
2-19.99 mS/cm
20-199.9 mS/cm
0to50°C
Resolution ±0.1
±1
±10
±100
Readout 3
1
digit LCD
2
Controls SLOPE
CONDUCTIVITY
mS/ppm
mS/ppt
°C
OFF
Temperature
Automatic by separate probe
Compensation
Probe Carbon electrodes; 3 ft. cable
Power 1604A Alkaline Battery (9 volt)
3.5 mm jack adapter
7
1
Size 5
“x3
8
3
”x1
“(15cmx8cmx5cm)
4
4
ACCESSORIES
Description Code #
AC Adapter 1708
Funnel 0459
Filter Paper 0465
Cond. Std., 0.0005M KCl, 74 mmhos/cm 6416-L
Cond. Std., 0.005M KCl, 718 mmhos/cm 6417-L
Cond. Std., 0.01M KCl, 1,413 mmhos/cm 6354-L
Cond. Std.,0.05M KCl, 6,668 mmhos/cm 6418-L
Cond. Std., 0.5M KCl, 58,640 mmhos/cm 6419-L
6
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