YSI Model 52, Operation Manual

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YSI, Incorporated Model 52 13
SECTION 5 OPERATION
5.1 TEMPERATURE MEASUREMENTS
Allow 3 to 5 minutes for temperature equilibration, and then take the temperature
reading.
5.2 DISSOLVED OXYGEN MEASUREMENTS
While the selector switch is set to O
2
-TEMP, place the prepared probe in the sample to be
measured. Allow 3 to 5 minutes for temperature equilibration, or wait for the * to display
if using the autostable feature. See section VIII B.. Begin stirring at least 30 seconds
before taking readings. Observe readings for stability and record measurements. The last
digit suppression feature of the Model 52 can be activated and deactivated by pressing the
SKIP button. This feature will “hide” the last digit in both the mg/L and % oxygen
readings and round each reading to the nearest whole digit.
5.3 MEASURING OXYGEN IN FLUIDS OTHER THAN WATER
The Model 52 is normally used for measuring the oxygen content of naturally occurring
waters and of wastewaters. The % air saturation mode also permits oxygen measurement
in some non-water fluids including air, most gases, foods, and some non-aqueous liquids.
Fluids which are suitable for measurement are those which do not attack the sensor
materials and are of sufficiently low viscosity to permit sample stirring across the probe
membrane. Strong acids and solvents capable of swelling or dissolving the ABS plastic
body of the probe or the EPR O-ring must be avoided. (See the list of interfering gases in
Appendix A.) The % air saturation of any fluid not excluded in the foregoing may be
measured directly. Calibrate by the customary air calibration technique and measure as in
natural waters.
Disregard the mg/L reading when measuring non-aqueous liquids. Such samples may
have an oxygen solubility or Bunsen coefficient significantly different from those used in
the Model 52.