YSI ProDSS Meter Calibration and Maintenance
K:\Streamkeepers\Monitoring\Eqpt & supplies\Calibration-Maintenance\SOPs\YSI ProDSS maint-
cal SOP's
9
8.
The meter should now be calibrated. For added assurance, rinse the probe in purified water,
shake off excess water and take a reading in air only. It should be ZERO. If not, repeat
calibration steps.
9.
Record the post-calibration conductivity reading and temperature on the data sheet.
10.
Rinse the sensors and calibration cup with clean water and proceed to pH calibration.
If data does not stabilize after 40 seconds:
-
Gently rotate the sensor, or remove/reinstall the calibration cup to make sure that no air
bubbles are in the conductivity cell
-
If the actual measurement data is about 1/2 if the expected calibration value, the conductivity
sensor is not completely submerged. Add more calibration standard to the calibration cup
-
If you get calibration error messages, check for proper sensor immersion, verify the
calibration solutions is fresh, the correct value has been entered into the ProDSS, and/or try
cleaning the sensor (reference the
Maintenance
section below on proper cleaning techniques
for the conductivity sensor)
pH Calibration
Equipment Needed:
•
pH Calibration Protocol & Data Sheets notebook
•
YSI ProDSS meter
•
Purified water
•
Kimwipes
•
pH 4, 7 and 10 buffer solutions
A note about pH millivolts (mV):
Millivolts (mV) are a way to troubleshoot calibration problems, they can help identify if the
buffer solutions are bad, or if the sensor needs replaced. Below is the proper range for mVs in
the designated buffers:
o
Buffer 7: -50 to +50 mV
o
Buffer 4: +165 to 185 above buffer 7 mV value
o
Buffer 10: -165 to -185 above buffer 7 mV value
If these values are not being produced during calibration, do the following:
-
Remove the sensor from the calibration cup and rinse the sensor and calibration cup with
clean water
-
To rule out that the buffer is bad, get a
fresh
pH 7 buffer, rinse the sensor with a small
amount of buffer and re-calibrate
-
If mVs are still not showing accurate readings, the sensor may need to be replaced, check
the purchase sticker on the long term storage bottle (pH sensor has a 1-2 year life
expectancy)
Perform a 3-point calibration of the pH meter before every monitoring session. Replace buffer
solutions as needed so as not to exceed expiration dates. Solutions are good until the last day of
the month listed. Anytime a new lot number of buffer is put into use, calibrate the instrument
with the new lot and check the old lot to be sure the results are similar (see below)
