Hach 900 MAX - Manual (Page 77)

Section 5
Page 75
8990options.fm Dissolved Oxygen Probe
5.4.3 Dissolved Oxygen Probe Temperature Programming
1. From the Main Menu, select OPTIONS>ADVANCED OPTIONS>DATALOG
2. Highlight Select Inputs using the UP and DOWN keys and press SELECT .
3. Highlight D.O. Temp. using the UP and DOWN keys, then press SELECT .
4. Cycle between Logged and Not Logged, then press ACCEPT .
5. Enter a logging interval using the numeric keypad, then press ACCEPT .
Valid logging intervals are shown on the status bar.
6. Select temperature units (°C, °F) using CHANGE CHOICE . Press ACCEPT .
5.4.4 Dissolved Oxygen Probe Calibration
The Dissolved Oxygen Probe is shipped without an electrolyte or membrane
installed. Install these items before initial use.
1. Connect a suitable power supply to the sampler, and power up the unit by
pressing the
ON button.
2. From the Main Menu, select OPTIONS > ADVANCED OPTIONS >
CALIBRATION > DO.
3. Enter the ambient air temperature (the current reading is displayed for
reference) using the numeric keypad.
4. Enter the elevation above sea level for the specific location.
5. Enter the membrane thickness. The operation of the sampler will be
affected by membrane thickness for the oxygen sensor.
Note: The membrane of a charged
sensor must be kept moist. If the
membrane is allowed to dry
completely, the electrolyte film
between the membrane and the
platinum will evaporate,
destabilizing the sensor. If the
sensor will be out of water for more
than 30 minutes, put a small amount
of water in the silicon soaking cap,
and install it over the protective
guard. Lift the edge of the cap to
break the seal as it is being
removed. This will prevent a vacuum
from forming inside the soaking cap
while it is being removed which can
result in the membrane becoming
stretched. For general purpose applications, the 1-Mil membrane is standard. This
membrane allows measurements in the 0 to 20 ppm range of dissolved
oxygen and provides the best response time and durability.
The 2-Mil membrane can be used to measure up to 40 ppm dissolved oxygen.
Its increased thickness slows the response time of the sensor, but this
membrane has increased resistance to cuts and tears. For this reason, it is
recommended for use in wastewater aeration basins where solids in the water
are in rapid motion.
6. Enter the chlorinity (salinity) of the flow stream (typical wastewater is zero,
sea water is higher).
7. Place the D.O. probe in open air and press any key. The sampler will wait
for the reading to stabilize before storing the calibration value. The screen
will automatically return to the calibration menu.
Calibrating the D.O. Temperature
1. Place the probe and the thermometer in a liquid.
2. Wait for the temperature reading to stabilize.
3. Enter the actual temperature of the liquid.