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TDS 5 Meter
Manual
LaMOTTE COM PANY
Helping Peo ple Solve An a lyt i cal Challenges
PO Box 329 • Chestertown • Maryland • 21620 • USA
800-344-3100 • 410-778-3100 (Outside U.S.A.) • Fax 410-778-6394
Visit us on the web at www.lamotte.com
SM
626094-23 • 7/03
The LaMotte 5 Series
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Contents
What is Conductivity? .........................4
The TDS 5 Meter ............................5
Display & Keypad Functions ......................6
Meter Specifications ..........................7
Accessories ...............................7
Meter Set-up .............................8-9
TDS Calibration ..........................10-11
Temperature Calibration ........................12
Measuring TDS ............................13
Measuring the TDS of Soil .....................14-15
Measuring Temperature ........................16
Probe Care ...............................17
Error Messages .............................18
Troubleshooting ............................19
Warranty Information .........................20
22 TDS 5 METER TDS 5 METER 3
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What is 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.
A commonly used factor is 0.7.
Conductivity is measured in microsiemens per centimeter (µsiemens/cm).
Siemens are also called mhos. In waters of higher conductivity,
µsiemens/cm may be multiplied by 1000, giving results as millisiemens per
centimeter (msiemens/cm). Total dissolved solids are measured in parts per
million. Therefore, using the information discussed above:
µsiemens/cm x 0.7 = ppm TDS
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.
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Warranty Information
The TDS 5 Meter
Repairs
If it is necessary to return the instrument for repair, contact LaMotte
Company at 1-800-344-3100 for a return authorization number.
Instrument Guarantee
This instrument, excluding the probe, is guaranteed to be free of defects in
material and workmanship for two years from date of original purchase. If
in that time it is found to be defective, it will be repaired or replaced
without charge, except for transportation expenses. This guarantee does
not cover the batteries.
This guarantee is void under the following circumstances:
u
Operator’s negligence
u
Improper application
u
Unauthorized servicing
Limits of Liability
Under no circumstances shall LaMotte company be liable for loss of life,
profits, or other damages incurred through the use or misuse of their
products.
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 TDS 5, see
Probe Care on page 17.
Conductivity/TDS 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.
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 percent per °C, accurate temperature
measurements must be made simultaneously to the conductivity reading.
The TDS 5 includes a temperature sensor within the probe to measure the
temperature. The meter has a protective rubber boot.
To make TDS readings taken at different times and places comparable,
measurements are often converted to what the TDS of the solution would
be at 25°C. The TDS 5 automatically makes this conversion before
providing a final reading.
Packaging and Delivery
Experienced packaging personnel at LaMotte Company assure adequate
protection against normal hazards encountered during shipping. After the
product leaves the manufacturer, all responsibility for its safe delivery is
assured by the transporter. Damage claims must be filed immediately with
the transporter to receive compensation for damaged goods.
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HO
LO
°C
pptm
1.8.8.8
indicates
HOLD
function
is activated
indicates
low
battery
condition
indicates
operation mode
Degree C annunciator
ppm, ppt annunciators
for TDS readings
Reading
µS, mS
annunciator
for conductivity
readings
mµS
Display and Keypad Functions
ON
OFF
CAL
MODE
HOLD
ENTER
Troubleshooting
Problem Check Action
ON/OFF :Turns the meter on and off
HOLD/ENTER: Freezes the measured reading or confirms the calibration
value.
CAL: Allows calibration of the meter for TDS and temperature
MODE/INC: Selects the parameter to be measured: TDS or temperature
: Scrolls display values up or
down to select
calibration values
LO Message
Power on but no display
Unstable reading
Slow response
Display locked
Unable to calibrate
Batteries
Batteries
Batteries
Batteries
Probe
Probe
Interference
from nearby
motor
Probe
Probe
Electrical
discharge
near meter
Probe
Replace
Insert batteries
Verify correct polarity
Replace
Immerse probe more deeply in
sample
Replace probe
Remove or switch off
Clean probe
Clean probe
Switch meter off and then on
again. Remove batteries and
reinsert.
Clean probe
Calibration
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standard
Select standard within range
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Error Messages
Error
Message Indicates Solution
E 2
E 3
Ur
Or
Microprocessor
Error
Microprocessor
Error
Temperature under range
Faulty sensor
TDS over range
Temperature over range
Faulty temperature sensor
Recalibrate instrument
Turn meter off and then on
again. Contact LaMotte for
return authorization
Warm sample
Contact LaMotte for return
authorization
Dilute sample
Cool sample
Contact LaMotte for return
authorization
Meter Specifications
Range: 0.0 to 99.9 ppm 0.0 to 50°C
100 to 999 ppm
1.00 to 9.99 ppt
Auto Ranging
Resolution: 0.1 ppm 0.1°C
1 ppm
0.01 ppt
Accuracy: +/- 2 ppm +/- 0.5°C
+/- 20 ppm
+/- 0.2 ppt
(+/- 2% of full scale)
Calibration: Up to 3 points offset 0.1°C increments
TDS Factor: User adjustable 0.5 to 0.85
Cell Constant: 1
Auto Shutoff: after 17 minutes
Automatic Temp.
Comp.:
Reference Temperature: Factory set at 25°C
Temperature Coefficient: Factory set at 2% per °C
Keys: ON/OFF, HOLD/ENTER, MODE/INC, CAL,
Power: 4 AAA Alkaline Batteries
0.0 to 50°C
s/t
Accessories
Description Order #
TDS/Temp Probe 5-0042
Conductivity Standard, 52 ppm TDS, 500 mL 6416-L
Conductivity Standard, 503 ppm TDS, 500 mL 6417-L
Conductivity Standard, 989 ppm TDS, 500 mL 6354-L
Conductivity Standard, 4668 ppm TDS, 500 mL 6418-L
Protective Rubber Boot 5-0040
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Meter Set-up
Probe Care
Inserting the batteries
1. Remove the rubber boot.
2. Open the battery compartment on the
back of the meter.
3. Insert four AAA batteries. Note
polarity.
4. Replace cover and press it down until it
clicks.
5. Replace the rubber boot.
NOTE: A “LO” annunciator in the LCD will indicate when battery power is
low. Replace the batteries as soon as possible.
Connecting the Combination
TDS/Temperature Probe
1. Slide the BNC connector over the
receptacle on the meter. Make sure
the pin on the meter connector is in
the lower end of the slot.
2. Turn the outer ring on the BNC
connector until the pin slides to the upper end of the slot.
3. Insert the small plug into the jack on the meter.
NOTE: If the temperature probe is not connected, the temperature reading (°C)
will default to 25 °C.
A dry probe should be soaked for at least 10 minutes before use.
Never scratch the stainless steel portions with a hard surface.
Do not strike the probe against hard surfaces.
Keep the TDS probe clean. Rinse the probe with deionized water or tap
water before storing it. The probe may be cleaned by swishing it in a mild
detergent bath and then wiping it with soft tissue paper. The probe should
then be rinsed with tap water and then rinsed in deionized water. Clean
the probe with alcohol to remove oils, films or oxidation. Recalibrate the
meter after cleaning the probe.
NOTE: Wet the probe for 10 minutes before performing the calibration
procedure or taking readings in order to saturate the probe surface and minimize
drift.
Turning the meter on
The ON/OFF key will turn the meter on. All of the LCD segments will be
displayed for a few seconds as the meter goes through a self-diagnostic test.
The meter will then switch to the TDS measurement mode.
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Measuring Temperature
Meter Set-up, continued
Setting the Conductivity-to-TDS Conversion Factor
The TDS 5 meter has a default conversion factor of 0.67. Using this factor
should give good results for most applications (including natural waters and
other applications that calibrate to 442 standard solutions). Follow the
procedure below to adjust the factor for different salts, chemicals, or
nutrient solutions.
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TDS Calibration
3.
1. 2.
4.
Press the ON/OFF
key to turn the
meter on and to
enter the TDS
mode.
1
2
Pour approximately 3 cm of a
conductivity standard into two
separate containers.
Conductivity
Standard
3 cm
1
2
Gently stir the first
container of the
standard with the
probe. This
container will be
used as the rinse
solution to remove
contaminants.
1
2
Immerse the
probe in the
second
container of the
standard.
CAL
MODE
HOLD
ENTER
HOLD
ENTER
ON
OFFONOFF
The meter is capable of up to a three-point calibration. Only one
calibration is needed for the entire range of the meter but better accuracy
will be achieved if each range is calibrated. If a range is not calibrated, the
meter will automatically calibrate to the range closest to the sample being
tested.
Calibrate the meter at least once a week if solutions with a conductivity of
less than 50 ppm are being measured in order to get +/- 2% full scale
accuracy. If solutions are being measured with conductivity in the mid
range, and the probe is washed in deionized water and stored dry, the meter
need only be calibrated once a month. Calibrate the meter at least once a
week if measurements are taken at extreme temperatures.
Select a TDS standard with a concentration near the sample to be
measured. If this is not possible, choose a value that is approximately 2/3 of
the full scale value of the measurement range. For example, in the 100 to
999 ppm range, the meter should be calibrated with a 989 ppm solution.
NOTE: The meter will not accept calibration values less than 20 ppm. All new
calibrations will automatically override existing calibrations.
Measuring the TDS of Soil
10 TDS 5 METER TDS 5 METER 15
continued...
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TDS Calibration Measuring the TDS of Soil
continued...
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Temperature Calibration
The temperature probe is factory calibrated. Over time, the temperature
calibration may drift and require recalibration. The temperature should be
recalibrated prior to TDS calibration if the probe has been replaced.
Measuring TDS
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