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4.3.5 Test pH sensor
4.3.6 Test float bladder
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1. Enter w to start the IsusAgent>.
2. Enter p to use the SBE 41cp to set pressure, temperature, and salinity. This must be
done before a nitrate sample can be taken.
3. Enter e to see the error report for the SUNA.
4. Enter i to start ("initialize") the SUNA internal variables.
5. Enter r to set the RTC to agree with the N2.
6. Enter s to take a nitrate sample.
A value of 0–2 µM is typical in air.
7. Enter u to see the most recent sample.
8. Enter t to see the timeout value.
9. Enter q to stop ("quit") the IsusAgent.
The c>prompt shows again.
The pH sensor is shipped dry, but was pre-conditioned in seawater from the Pacific
Ocean near Hawaii. (When the pH sensor adjusts to the specific ionic concentration of
region-specific seawater, it is "conditioned.") Once it is wet it takes a minimum of several
hours to re-condition, but three days is recommended. The sensor does not need to be
calibrated again after it is conditioned.
The manufacturer recommends that the user supply power to the isolated battery and put
the pH sensor in natural seawater that is similar to the deployment site several days
before deployment. Seawater makes a half-cell bridge between the Counter Electrode
and the ISFET. The sensor should be stored dry to prevent biofouling, and the battery
can be removed.
This is a very delicate sensor that must be flushed with ONLY filtered and UV-sterilized
natural seawater. Do not use Seawater Certified Reference Material (CRM), synthetic
seawater, de-ionized water, NaCl solutions, or tap water. The manufacturer recommends
that the user fill the CTD tubing with filtered and UV-sterilized natural seawater when the
float is in the laboratory.
1. Enter xb to turn on the pH battery.
2. Enter xn to see the serial number of the pH sensor. Make sure that it agrees with the
label on the pH stem.
3. Enter xm to see the current draw. It should read less than 0.2 watts.
4. Enter xs to take a pH sample.
•
vrs value: -0.8 to -0.95
•
vk value: -0.8 to -1.0
•
ik and ib should be less than -1e
•
Battery voltages should read 7.0 ± 0.5 V.
Notes:
•
Streaming commands have not been tested in the field.
•
If profiling commands such as phall are used, send isooff when done with data
streaming, or the battery will continue to draw 750 µA.
•
Ignore the date and time from the sensor. This is erased every time the float is in a
low power mode, even if power is supplied to the SBE 41cp.
•
The SBE 41N does not collect samples at exactly 1 Hz: for best accuracy, samples
should be time-stamped when received.
Make sure that the air system functions correctly.
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