LaMotte DO 4000 Dissolved Oxygen Meter User Manual

Page 11

CALIBRATION
The DO 4000 should be recalibrated daily using one of the following

methods to account for changing environmental conditions. For most

accurate results, calibrate as close to the temperature of the sample to be

tested as possible. DO NOT CALIBRATE WITH THE SHEATH

ON.
The saturated air calibration is easiest and generally considered to be a

very accurate and reliable procedure. Alternative methods are listed on

pages 12-16.
NOTE: If the DO 4000 has not been set on the constant polarization

mode, set constant polarization button to out position on top of meter

and wait 15 minutes before calibrating.
SATURATED AIR (RECOMMENDED PROCEDURE)
NOTE: It is very important that the membrane be completely dry

before starting air calibration. Vigorously shake the probe several times

to remove water droplets from the membrane. However, calibration

must be done in humid not dry air!
1. Hold the probe several inches above water surface.
2. Set “SALINITY COMP” knob to 0. Press “%SAT” button to turn

the meter on. Wait for display to stabilize.

3. Adjust the “SLOPE” control until display reads 100. The meter is

now calibrated for use. Turn off constant polarization unless meter is

to be used again shortly.
NOTE: If readings are erratic, or the meter can not be calibrated

see Troubleshooting on page 18.