Extech Instruments 34135-A User manual

Version 1.5 August 2001
User's Guide
Oyster pH - Conductivity - TDS - Temperature Meters
Models
34135-A
341350
341350-P
34145A
341450
341450-P
INTRODUCTION
Congratulations on your purchase of the Extech's Oyster Series meter or meter kit. These
devices measure pH/Conductivity plus TDS or Temperature. These meters are intended for
routine laboratory and field testing. Accurate measurements are provided in a battery
operated, portable meter with a hinged display that can be adjusted to any viewing angle.
Model 34135-A measures pH, Conductivity and TDS. The ‘A’ indicates ‘meter-only’.
Models 341350 and 341350-P are kits which include the 34135A and all the necessary
accessories. The ‘P’ indicates Polymer type electrode (341350 has glass electrode).
Model 34145-A measures pH, Conductivity & Temperature. ‘A’ indicates ‘meter-only’.
Models 341450 and 341450-P are kits which include the 34145A and all the necessary
accessories. The ‘P’ indicates Polymer type electrode (341450 has glass electrode).
Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176
FAX [phone] - TestEquipmentDepot.com
99 Washington Street
Melrose, MA 02176
Phone [phone]
Toll Free 1-800-517-8431
Visit us at www.TestEquipmentDepot.com
Back to the Extech 341350 Product Page

Version 1.5 August 2001
2
SPECIFICATIONS
Range (resolution) Accuracy
Conductivity 10 - 19,990µS (10µS) ± 0.5%
Temperature (34145-A only) -30 to 105oC ± 0.50C
pH 0.00 to 14.00pH (0.01pH) ± 0.02pH
TDS (34135-A only) 10 - 19,990ppm (10ppm) ± 0.5%
Auto/Manual Temperature
Compensation
Manual for pH/Auto for conductivity/TDS; 0-100oC;
Correction: 2% per oC
Power 9V battery or optional AC adapter
Display 3-1/2 Digit LCD (90 to 180oadjustable viewing angle)
Overrange Indication Automatic (1---) on all ranges
Low Battery Indication Automatic
Dimensions/Weight 3.75 x 4.25 x 2" (96 x 108 x 45mm) / 12 oz (340g)
Accessories supplied 9V battery, plus:
341350 kit pH electrode, pH buffers, bottle, case, glass
conductivity cell
341350-P pH electrode, pH buffers, bottle, case, polymer
conductivity cell
341450 kit pH electrode, pH buffers, bottle, case, glass
conductivity cell, stainless steel temperature probe
341450-P pH electrode, pH buffers, bottle, case, polymer
conductivity cell, stainless steel temperature probe
METER DESCRIPTION
1. LCD display
2. Battery compartment
3. AC adapter input
4. Electrode and Temperature
probe input jacks
5. Electrode
6. Neck-strap fasteners
7. Function keys
1
2
5
6
3
7
4

Version 1.5 August 2001
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OPERATING INSTRUCTIONS
pH Calibration
1. Calibrate the meter and electrode before each use to ensure accuracy.
2. Connect the pH electrode via the BNC connector to the meter.
3. Open the meter to the fully extended position. Open the battery cover and install a 9V
battery. Replace the cover and turn the unit ON. The LCD indication should appear.
4. Slide the SELECT switch to pH
5. Adjust the TEMP oC knob to approximate the solution temperature.
6. Remove the wetting cap from the tip of the electrode. Rinse in de-ionized water, blot
dry and place the electrode in a 7.00 pH buffer solution. Allow to stand for
approximately one minute or until the display stabilizes.
7. Adjust the CALIB knob until the display reads 7.00.
8. Remove the electrode from the buffer and rinse it in distilled water and blot dry. Place
the electrode in a 4 or 10 pH buffer solution and allow to stand for approximately 1
minute or until the display stabilizes.
9. Adjust the SLOPE knob until the display reads 4.00 or 10.00 (as required).
10. Repeat steps 6 through 9 until no further adjustment is necessary.
pH Measurement
1. Place the electrode in the sample solution and read the pH value on the LCD.
2. When all measurements have been taken, unplug the electrode or cell and rinse in
distilled water, shake and store as described below.
Conductivity / TDS Calibration
The conductivity cell calibration should be performed frequently to ensure accuracy.
1. Connect the conductivity cell to the input socket on the side of the meter.
2. Prepare a conductivity solution of approximately the same value as the solution to be
measured. The solution should be prepared at 250C.
3. Set the meter to the uS/cm or TDS mode.
4. Place the cell in calibration solution and allow the reading to stabilize.
5. Adjust the Cell knob until the display reads the value of the calibration solution.
Example: For a 12560uS/cm conductivity solution the display will read 1256. The
user must multiply the reading x 10.
Conductivity/TDS Measurements (Multiply readings by 10)
1. Place the electrode in the sample solution.
2. When finished, unplug the electrode or cell and rinse in distilled water.
Temperature Measurement (34145-A only)
1. Set the mode switch to Temperature.
2. Connect the temperature probe to the meter via the meter’s phone jack.
3. The LCD will indicate the temperature in oC.
4. Immerse the probe at least 1/3 of the way below the surface of the solution.
5. Allow enough time for the electrode to reach the sample’s temperature.
Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176
FAX [phone] - TestEquipmentDepot.com

Version 1.5 August 2001
4
Care of the Conductivity/TDS Cell
To prepare the cell, remove any outer protective sheath that may be used in shipping.
1. Cell Storage
On sheathed cells, replace the sheath over the cell when storing. For non-sheathed
versions, soak the cell tip in de-ionized water for storage.
2. Cell Cleaning
After each use, the cell tip should be rinsed with de-ionized water. If solids build up
inside the cell carefully remove with a cotton swab soaked in solvent taking care not
to touch the metal parts of the inner cell.
3. Internal Cell Elements
Two platinum plates reside on the inner cell wall. These plates should be a uniform
black color. If blemishes and scratches appear on these plates, the cell may need
repair. If this occurs, it is suggested that the cell be returned for evaluation.
Care of the pH Electrode
1. The 60120B pH electrode is recessed in the polymer body allowing it to rest against
the bottom of a beaker without damage the glass bulb. This eliminates the need for
electrode holders and allows the probe to be used as a stirring rod. The sealed
reference design eliminates the need for filling solutions (minimizes "dry-out"). Up to
100 psig systems can be accommodated without external pressurization.
2. The Electrode should remain in its bottle or cap until used. Afterwards, store the
Electrode in its bottle. Use a pH 4 buffer solution or tap water as the storage medium.
3. If bubbles are seen in the bulb area, hold the electrode by its cap and shake
downwards until bubbles are removed.
4. To improve speed of response, vigorously stir the electrode in the sample, buffer, or
rinse solution.
5. After exposure to a sample, buffer, or rinse solution, shake the electrode with a snap
motion to remove residual drops of solution.
6. Use part of the next sample/buffer to be measured as a rinse solution, when possible.
7. When calibrating, use a buffer as close as possible to the expected pH of the sample.
8. Keep buffers and samples at the same temperature to avoid temperature effects.
9. pH readings stabilize faster in some solutions than others; allow time to stabilize.
10. Electrodes deteriorate over time. If accuracy falls to 10% the electrode should be
cleaned or replaced. If no improvement is observed, replace the electrode at once.
Electrode Storage
The electrode can be stored in the soaker bottle or wetting cap. For the storage bottle,
slide the cover onto the electrode, replace the O-ring, and insert electrode into bottle firmly
tightening the cap. Ensure that the bottle or cap is filled with a pH 4 buffer or tap water.
Electrode Cleaning
The type of electrode coating which occurs over time will determine the cleaning method.
Soft coatings can be removed by vigorous stirring or by the use of a squirt bottle. Organic
chemical (hard coatings) should be chemically removed. Only in extreme cases should the
bulb be cleaned mechanically.

Version 1.5 August 2001
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pH Troubleshooting Chart
Symptom Cause Recommended Solution
Clogged Junction Soak in 4.07 M KCL @ 60oC for 30
minutes
Strong Alkaline measurement
Deteriorated Gel layer
Soak in 0.1 M HCL overnight
Protein coating on electrode
surface
Soak in 1 gm Pepsin dissolved in
100ml of 0.1 m HCL for 30 minutes or
as needed
Oil, paint, dyes, suspended solids
on sensor
Rinse electrode alternately with
materials solvent then buffer 7.00
Organic solvents are coating
sensor
Long response
time or reading
drift
Dehydrated membrane
Organic mole fraction has to be less
than 50% to assure reasonable
readings. Limit time of measurement.
Keep probe in the 7.0 buffer between
readings.
Dry Bulb Long term storage without wetting Soak electrode tip in wetting cap filled
with 1ml 7.00 buffer for 24 to 48 hours
Static Charge Wiping electrodes Rinse electrode in 7.0 buffer and blot.
Do no wipe electrode.
Same readings in
different buffers
and samples
Cracked or broken bulb Replace electrode. Use bulb guard.
Avoid plunging electrode to bottom of
container and spinning bars. A
wetting cap will protect bulb between
measurements.
Erratic LCD
display
Samples have low ionic strength
(lacks salt); e.g. distilled, de-
ionized, boiled, lake water (high
pressure)
For each 50 ml of sample add 1 drop
(50uL) of SAT.KCL No alteration in
pH will occur by inert KCL.
MAINTENANCE
Conductivity Cell Simulator
The meter is supplied with a cell simulator which can be used in place of the conductivity
cell to provide a means to verify the operation of the meter. The simulator will produce a
reading of approximately 800 - 1200uS (~1mS). The simulator should not be used as a
calibration device.
This device is helpful in determining if the cause of calibration difficulties is related to the
meter or (more likely) an aged or defective conductivity cell.
Battery Replacement
Install a new battery when the LOW BATTERY indication appears on the LCD. Remove
the battery cover (refer to Fig. 1 for location), install new battery, and replace cover.
Calibration / Repair Services
Extech offers complete repair and calibration services for all of the products we sell. For
periodic calibration, NIST certification or repair of any Extech product, call customer
service for details on services available. Extech recommends that calibration be performed
on an annual basis to insure calibration integrity.
Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176
FAX [phone] - TestEquipmentDepot.com