Extech SDL150 User guide

User's Guide

Dissolved Oxygen (DO) Meter

SD Card real-time Datalogger

Model SDL150

1

2

3

4

5
6

7

8

9

10

11
12

13
14
15

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 50oC (32 to 122oF). The SDL150
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.

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 key

5. SET and Clock key

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 key

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

2

SDL150-EU-EN-V2.1-11/11

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.

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 at 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.

3

SDL150-EU-EN-V2.1-11/11

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 50oC (32 to 122oF) 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).

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 50oC (32 to 122oF) on the lower LCD line in
smaller sized digits.

4

SDL150-EU-EN-V2.1-11/11