YSI 6500 Environmental Process Monitor - Manual (Page 41)

Laboratory and Field Calibration Section 4
CONTAINERS NEEDED TO CALIBRATE A SONDE
The calibration cup that comes with your sonde serves as a calibration chamber for all calibrations.
You need to visually observe the turbidity calibration to insure that no air bubbles are trapped near
the optics and that standards are homogeneous. If you are using the 6026 “wiping” turbidity probe,
you should visually verify proper movement of the wiper mechanism. Turbidity must be calibrated
with the probe guard on the sonde.
Instead of the calibration cup, you may use laboratory glassware to perform calibrations. If you do
not use a calibration cup that is designed for the sonde, you are cautioned to do the following:
T Perform all calibrations with the Probe Guard installed. This protects the probes from possible
physical damage.
T Use a ring stand and clamp to secure the sonde body to prevent the sonde from falling over.
Much laboratory glassware has convex bottoms.
T Insure that all sensors are immersed in calibration solutions. Many of the calibrations factor in
readings from other probes (e.g., temperature probe). The top vent hole of the conductivity
sensor must also be immersed during calibrations.
TIPS FOR GOOD CALIBRATIONS
1. If you use the Calibration Cup for dissolved oxygen (DO) calibration,
make certain to loosen the seal to allow pressure equilibration before
calibration. The DO calibration is a water-saturated air calibration.
2. The key to successful calibration is to insure that the sensors are
completely submersed when calibration values are entered. Use
recommended volumes when performing calibrations.
3.
For maximum accuracy, use a small amount of previously used
calibration solution to pre-rinse the sonde. You may wish to save old
calibration standards for this purpose.
4.
Fill a bucket with ambient temperature water to rinse the sonde between
calibration solutions.
5.
Have several clean, absorbent paper towels or cotton cloths available to
dry the sonde between rinses and calibration solutions. Shake the excess
rinse water off of the sonde, especially when the probe guard is installed.
Dry off the outside of the sonde and probe guard. Making sure that the
sonde is dry reduces carry-over contamination of calibrator solutions and
increases the accuracy of the calibration.
YSI Incorporated 6500 Environmental Process Monitor 38