YSI ProDSS Meter Calibration and Maintenance
K:\Streamkeepers\Monitoring\Eqpt & supplies\Calibration-Maintenance\SOPs\YSI ProDSS maint-
cal SOP's
15
Pre-Monitoring Session Calibration Procedures
The DO sensor should have already been inspected for cleanliness during sensor installation, but
if the sensor is visibly dirty, refer to the
Maintenance
section below for proper cleaning
procedures.
DO Zero-Point Calibration
Before each quarter, the following procedure should be performed to assure that the sensor is
reading accurately in near-zero dissolved oxygen conditions, so that its internal “zero-dissolved-
oxygen” point is being set properly:
1.
Put on safety equipment: goggles, gloves
2.
Make a solution using ~ 3g sodium sulfite/375 mL DI water. Stir to dissolve and allow to sit
for at least 60 min.
3.
Pour the sodium sulfite solution into a 1000 mL graduated cylinder
4.
Place DO probe in the sodium sulfite solution.
5.
Select the
calibration button
, then select ODO, then Zero.
6.
Confirm stabilization by watching the
actual readings
on the screen, if DO% and Temp
remain within ± 0.1 for 2 minutes, the sensor is stable.
7.
After observing stabilization, press Accept Calibration. “Calibration Successful!” will be
displayed on the screen.
8.
Record results on the data sheet.
9.
Rinse the probe thoroughly with DI water before placing it back in the calibration cup - this
is important or it could mess up future calibrations.
10.
Proceed to DO% calibration
DO Calibration
Calibrating in DO% automatically calibrates the mg/L measurement. There is no reason to
calibrate both parameters.
1.
Make sure the DO sensor setting is set to “DO% Local”:
a.
2.
Make sure the sensors and calibration cup have been rinsed following the preceding
calibration
3.
Make sure there are no water droplets on the sensor cap or temperature sensor. With a
Kimwipe or lint-free cloth, carefully wipe off any large droplets from the DO sensor tip and
the temperature sensor by inserting the Kimwipe through the open slots in the sensor guard.
If large droplets cannot be removed by wiping them away through the guard, remove the
sensor guard to get to the sensors. Note that the temperature sensor does not need to be
completely dry; drying the sensor at its base is hard to do and is not necessary.
4.
Pour a small amount of clean water (1/8
th
inch) gently down the side of the calibration cup
5.
Gently insert the sensor and guard into the calibration cup, partially tighten the calibration
cup to the bulkhead
IMPORTANT NOTE:
Do not fully tighten the cup, atmospheric venting is required for
accurate calibration. Make sure the DO and temperature sensors are not submerged in
