Extech SDL150 Operating Manual

USER GUIDE

Dissolved Oxygen (DO) Meter

SD Card real-time Datalogger

Model SDL150

Introduction

Congratulations on your purchase of the Extech SDL150 Dissolved Oxygen Meter, an SD Logger
Series meter. This meter displays and stores Dissolved Oxygen readings in the 0 to 20.0mg/L
range, Oxygen in air from 0 to 100%, and Temperature from 0 to 50
uses a polarographic oxygen probe that also measures temperature. %Salt and Altitude
compensation can be fine tuned by the user in the Setup mode. Logged data readings are stored on
an SD card for transfer to a PC. In addition, an RS232 port allows data streaming to a PC. This
meter is shipped fully tested and calibrated and, with proper use, will provide years of reliable
service.

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C (32 to 122oF). The SDL150

Safety

International Safety Symbols

This symbol, adjacent to another symbol or terminal, indicates the user
must refer to the manual for further information.

Meter Description

1. Oxygen Probe Input Plug

2. Dissolved Oxygen or Oxygen in Air reading

3. Temperature reading

4. Power ON-OFF

5. SET and Clock

6. Up arrow ▲ / CAL key

7. Down arrow ▼ / Function key

8. ENTER and LOG key

9. SD card slot

10. Dissolved Oxygen/Temperature Probe

11. HOLD and Backlight

12. MAX-MIN key

13. PC interface jack

14. Reset button

15. Power Adaptor jack

Notes:

Items 13, 14, and 15 are located behind the snap-off compartment cover on meter’s right side.

Battery compartment, tilt stand, and tripod mount are located on the rear of the instrument

key

key

2

3

4

5

key

6

7

8

1

10

11
12

13
14
15

9

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Probe Description

1. Probe to meter input plug

2. Probe body handle

3. Temperature Sensor

4. Probe head

5. Protective cap

1

2

3
4

5

Getting Started

Accessories

 The SDL150 includes batteries, SD card, probe (with spare probe head and

diaphragm), electrolyte, and carry case. If items are missing please contact the
distributor through which this product was purchased

 Optional AC adaptor and universal AC adaptors (UK, EU, US), as well as

replacement probes, membranes, and electrolyte are available through Extech
distributors

Power ON-OFF

 Press and hold the power button for at least 1.5 seconds to power ON the meter.
 Press and hold the power button for 1.5 seconds to power OFF the meter.
 This meter is powered by six (6) 1.5VDC ‘AA’ batteries or by optional AC adaptor. If

the meter will not switch ON please check that fresh batteries are installed in the rear
battery compartment or, in the case of the AC adaptor, check that the adaptor is
connected correctly to the meter and to an AC source.

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Measurements

Connect the Oxygen Probe

The supplied probe connects to the keyed input jack (DIN style) at the top of the meter.

Measurement Ranges

Dissolved Oxygen measurements are displayed in the range of 0 to 20mg/L in the upper,
larger digit display area of the meter’s LCD. Measurements outside of this range will
yield dashes (- - -) on the meter’s LCD. Oxygen in Air measurements (O2) are displayed
in the range of 0 to 100%. Temperature measurements are displayed in the range of 0 to
50oC (32 to 122oF) on the lower LCD line in smaller sized digits.

Calibration Considerations

For best accuracy, calibrate the meter with the probe before each use. The calibration
should be performed before first use and after long periods of non-use. The calibration
procedure is provided in a later section of this user guide.

Taking Dissolved Oxygen Measurements

1. Immerse the DO probe into the solution under test to a depth of at least 10cm. The
depth specification is important since the temperature measurement of the solution
and the automatic temperature compensation circuitry rely on the probe depth to
operate correctly.

2. Allow the test to stabilize for several minutes to achieve thermal equilibrium between
the probe and measurement sample.

3. To successfully measure DO the velocity of the solution striking the probe must be at
least 0.2-0.3m/s (meters per second); if not, simply agitate the solution with the probe
while waiting for thermal equilibrium to be achieved.

4. In laboratory environments use of a magnetic agitator to ensure proper velocity is
recommended. In this way, errors due to the diffusion of the oxygen present in the
surrounding air are minimized.

5. The Dissolved Oxygen measurements are displayed on the upper, larger digit display
area of the meter’s LCD. Measurements outside of the specified range will yield
dashes (- - -). Temperature measurements are displayed in the range of 0 to 50
(32 to 122

o

F) on the lower LCD line in smaller sized digits.

6. %SALT, Altitude (height) compensation, temperature units of measure, and other
parameters, can be modified in the SETUP mode (refer to the SETUP mode section
later in this guide).

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Taking Oxygen in Air Measurements

1. The probe measures Oxygen in the air surrounding the probe (in percent).

2. The meter defaults to the DO measurement mode. Therefore, press and hold the
FUNCTION button for 1.5 seconds to switch to the %O2 mode (oxygen in air). The
displayed unit of measure will switch from mg/L to 02. To return to the DO
measurement mode simply press and hold the FUNCTION button again for 1.5
seconds.

3. The Oxygen in Air measurements are displayed on the upper, larger digit display
area of the meter’s LCD. Measurements outside of the specified range will yield
dashes (- - -). Temperature measurements are displayed in the range of 0 to 50
(32 to 122

o

F) on the lower LCD line in smaller sized digits.

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C

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