Vernier Go Direct GDX-ODO Instruction Manual page 2

3. Place the tip of the probe into the water sample. The sample needs to be deep
enough that the metal ring on the tip is submerged. Note: If your water sample
is not at room temperature, wait a few minutes for the reading to equilibrate
before taking a reading.
4. When you are finished making measurements, rinse the probe with distilled
water.
5. Slide the lid onto the body of the probe, and then screw the lid onto the storage
bottle.
Channels
Go Direct Optical Dissolved Oxygen has five measurement channels:
DO Concentration
l
DO Saturation
l
Temperature
l
Pressure
l
DO Salinity
l
DO Concentration
This channel measures the dissolved oxygen concentration in a water sample. This
is an absolute measurement of dissolved oxygen concentration expressed as
milligrams of oxygen gas dissolved per liter of water. Units can be changed from
milligrams per liter (mg/L) to parts per million (ppm). Water temperature and
atmospheric pressure are being measured and used in the DO calculations
regardless of whether the temperature and/or pressure channels are activated. This
is the default channel that is active when the probe is connected.
DO Saturation
This channel measures the percent saturation of dissolved oxygen in a water
sample. Percent saturation is a relative measurement in which the dissolved
oxygen concentration is expressed as a percentage of the maximum amount of
oxygen that water can hold at a given temperature and pressure. This channel is
not active by default when the probe is connected.
Temperature
This channel measures water temperature of the sample. Units can be changed
from °C to °F, or K. This channel is not active by default when the probe is
connected, however it is always in use internally, along with pressure, to calculate
the dissolved oxygen readings.
Pressure
This channel measures the atmospheric pressure. Units can be changed from kPa
to mmHg, inHg, mbar, psi, atm, or torr. This channel is not active by default when
the probe is connected, however it is always in use internally, along with
temperature, to calculate the dissolved oxygen readings.
DO Salinity
This channel should be used when measuring dissolved oxygen in highly saline
environments (> 1 ppt). In these cases, a correction must be made to account for
the effect of salinity on dissolved oxygen concentration. Salinity is not actually
measured by the probe, but it can be manually entered once this channel has been
selected. If no value is entered, a default salinity concentration of 35 ppt, the
typical salinity of ocean water, is used to make the correction. Units can be
changed from milligrams per liter (mg/L) to parts per million (ppm). This channel
is not active by default when the probe is connected.
Calibrating the Sensor
DO Concentration
This channel is factory calibrated and does not require calibration by the user. If
the probe is not reading accurately, a reset can be done using a one-point
calibration. To do a reset
1. Fill the storage bottle to the top of the sponge with distilled water.
2. Insert the probe into the storage bottle and make sure it is positioned vertically
so that the tip is not in contact with the sponge or water.
3. Start the software and identify your probe, if necessary.
4. Keep the probe in a vertical position for a minimum of 60 seconds.
5. Click or tap the meter, choose calibrate, and follow the instructions on the
screen.
DO Saturation
This channel is factory calibrated and does not require calibration by the user. If
the probe is not reading accurately a reset can be done using a one-point
calibration. To do a reset
1. Fill the storage bottle, to the top of the sponge, with distilled water.
2. Insert the probe into the storage bottle and make sure it is positioned vertically
so that the tip is not in contact with the sponge or water.
3. Start the software and identify your probe, if necessary.
4. Keep the probe in a vertical position for a minimum of 60 seconds.
5. Click or tap the meter, choose calibrate, and follow the instructions on the
screen.
Temperature
This channel is factory calibrated and can not be calibrated by the user.
Pressure
This channel is factory calibrated and can not be calibrated by the user.
DO Salinity
This channel is factory calibrated and does not require calibration by the user. The
salinity correction is automatically set for 35 ppt. To change the correction, click
or tap the meter, choose calibrate, and enter the actual salinity concentration, in
ppt. Click or tap Keep, then done.
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