LaMotte DA-DS-1939 User Manual

CONDUCTIVITY/TDS METER

OPERATOR’S MANUAL

MODEL DA-DS · CODE 1939

SPECIFICATIONS

METER

A. Range:

0 - 5,000 micromhos/cm
0 - 3,500 Total Dissolved Solids

B. Accuracy:

2% full scale reading

C. Precision:

0.5% full scale reading

FUNCTION CONTROLS

A. Operation Switch:

BATCK - check battery reserve
OFF - turn meter off
CAL - calibrate instrument
ON - read conductivity or Total Dissolved Solids (TDS)

B. Calibration:

Calibrates instrument by regulating voltage potential

C. Temperature Compensation:

0-100oC - adjusts instrument to temperature of sample
being tested

D. Other Specifications:

Power: Single 9V Transistor Battery
Physical Dimensions: 3-3/4" width x 2-5/8" depth x 6-1/4"

Weight: 1.4 lbs
Jack Receptacle: accepts 9V AC Adapter, 3.5mm plug

height

Code 1708 (optional)

PROBE:

Range: 0-5,000 micromhos/cm
Size: 6" x 1/2"
Weight: 2 oz
Elements: Carbon (non-fouling)
Probe Constant: 5.0/cm
Connector: BNC

NOTES ON THE USE OF CONDUCTIVITY PROBE

1. The sensing element of the conductivity probe consists of thin metal
plates, rigidly supported in a rugged plastic material. These metal plates
have a very precise parallel spacing which determines the probe cell
constant. To keep this spacing and to assure accurate results, it is
essential that the probe is properly maintained and kept clean.

2. When conductivity measurements are made, the probe must be
immersed in sufficient solution to cover the bottom groove. The probe
may be completely immersed within the sample without adversely
affecting the results.

3. There is a tendency for the conductivity probe to entrap air bubbles
which may result in erroneous readings. After the probe is immersed in
the test solution, tap or “jiggle” the probe to remove trapped air
bubbles.

4. The conductivity probe must be kept from contacting the bottom or
sides of the containers which hold the sample. Contact with surfaces
other than the solution might result in inaccurate readings since the
current flow may be altered between the probe elements.

5. After the completion of the conductivity measurement, rinse inside and
outside of probe thoroughly with water, preferably distilled water. Allow
probe to drain completely before storing. The probe may be stored dry
indefinitely without any damage.

DETERMINATION OF CONDUCTIVITY &
TOTAL DISSOLVED SALTS FOR WATER

1. With control knob in the “OFF” position, meter pointer must balance
at zero. To adjust the zero position, use meter-zero adjusting screw (“X”
slot screw on front of meter face usually located under LaMotte logo
sticker). The mirror-faced scale insures accurate readings by eliminating
errors due to parallax problems when the indicating needle and the
scale are not properly aligned by the reader’s eye.

2. Plug the probe into BNC receptacle located above and to the left of
meter movement.

3. Switch the control knob to the “BATCK” position. Meter should
indicate greater than 4,000 micromhos/cm. If not, replace battery. (See
instructions for battery replacement.)

4. Set the “TEMP” knob at 25oC, and switch the control knob to the
“CAL” position. The meter should indicate exactly 5,000
micromhos/cm. If not, carefully adjust by using the “STD” knob.

5. Measure the temperature of the sample solution, set the “TEMP” knob
at the mark indicating the temperature. (Note the markings are in
centigrade.) Temperature has a pronounced effect upon conductivity,
and must be monitored accurately.

6. Immerse the probe into sufficient solution to at least cover the bottom
groove of the probe. Make sure all bubbles are removed from the probe.

7. Switch the control knob to the “ON” position and read either
Conductivity in micromhos/cm (top scale) or Total Dissolved Solids in
ppm (bottom scale).

8. After completing the conductivity measurement, switch control knob
to the “OFF” position and rinse probe thoroughly with water, preferably
distilled water and drain.

DETERMINATION OF CONDUCTIVITY &
TOTAL DISSOLVED SALTS FOR SOIL

An approximation of the Total Dissolved Salts (TDS) in soil is obtained by
making a soil extraction with distilled water and measuring the TDS of the
soil extract. For purposes of comparison, all TDS values are recorded at
25oC.

PROCEDURE

1. Fill a 50 mL beaker full with the soil to be tested. Tap it lightly to
eliminate any air trapped. Strike the excess soil off the surface.

2. Empty the contents of the beaker into a 250 mL wide mouth flask and
add 100 mL of distilled water.

3. Stopper and shake vigorously. Allow to stand for thirty minutes. During
the thirty minute waiting period the sample should be shaken
vigorously three or four times.

4. Filter the contents of the flask and collect filtrate in suitable
conductivity chamber.

5. Take TDS reading according to method given for General Operating
Procedure.

If the Soluble Salts as determined above are greater than 1,000 ppm, the
chlorides and sulfates should be determined in order to learn whether the
Soluble Salts are chlorides or sulfates. Usually in calcareous soils, the
sulfates represent gypsum and cause little injury to plants, while high
concentrations of chlorides might result in damage to the plants.
Greenhouse and sensitive plants may be damaged if the Soluble Salts are
over 500ppm of chlorides. Most other plants will grow well in soils
containing less than 1,000 ppm chlorides.

REPLACING THE BATTERY

When meter does not indicate greater than 4,000 micromhos in the
“BATCK” position, replace the battery. The battery is located under the
meter panel of the instrument. Carefully remove the panel by unscrewing
the four screws on the front of the unit and lift the unit out. Make sure
battery terminal contacts are aligned with the correct terminals. Replace
meter panel to instrument housing.

INSTRUMENT GUARANTEE

This instrument and probe, except for the battery, are guaranteed to be free
from defects in material and workmanship for six months from original
purchase date. If within that time the instrument is found to be defective,
it will be repaired without charge - except for transportation expense to
LaMotte Company, Chestertown, Maryland 21620.

This guarantee is void under the following circumstances: operator’s
negligence, improper application, and unauthorized servicing.

LIMITS OF LIABILITY

Under no circumstances shall LaMotte Company be liable for loss of life,
property, profits or other damages incurred through the use or misuse of
their products.

PACKAGING AND DELIVERY

Experienced packaging personnel at LaMotte Company assure the adequate
protection against normal hazards encountered in transportation of
shipments. After the product leaves the manufacturer, all responsibility for
its safe delivery is assured by the transportation company. Damage claims
must be filed immediately with the transportation company to receive
compensation for damaged goods.

Should it be necessary to return the instrument for repair or servicing, pack
instrument carefully in suitable container with adequate packing material.
Attach a letter to the shipping carton describing the kind of trouble
experienced. This valuable information will enable the service department
to make the required repairs more efficiently.

LaMOTTE COM PANY

Helping Peo ple Solve An a lyt i cal Chal lenges

PO Box 329 • Chestertown • Mary land • 21620 • USA

800-344-3100 • 410-778-3100 (Out side U.S.A.) • Fax [phone]

Visit us on the web at www.lamotte.com

SM

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