6
4.1 Turning The Instrument On
With the batteries installed correctly, press the ON/OFF key. The instrument will activate all
segments of the display for a few seconds, which will be followed by a self test procedure which
will last for several more seconds. The Model 63 will briefly display the cell constant of the
conductivity probe when the self test is complete. During this power on self test sequence, the
instrument’s microprocessor is verifying that the system is working properly. If the instrument
were to detect a problem, a continuous error message would be displayed. See the chapter
entitled Troubleshooting for a list of error messages.
7.23
pH
24.8
°C
4.2 pH Calibration
The YSI Model 63 MUST be calibrated before making pH measurements. Calibration may be
performed at 1, 2 or 3-points (at pH 7, 4 and 10, or at pH 6.86, 4.01 and 9.18). Perform a 1-point
calibration (at pH 7 or at pH 6.86) ONLY if a previous 2 or 3-point calibration has been
performed recently. In most cases, a 2-point pH calibration will be sufficient for accurate pH
measurements, but if the general range of pH in the sample is not known, a 3-point calibration
may be necessary. 3-point calibration assures accurate pH readings regardless of the pH value of
the sample. See 9.1 pH for more details.
WARNING: Calibration reagents may be hazardous to your health. Refer to Appendix B -
Health and Safety for more information.
Before calibrating the YSI Model 63, complete the procedures discussed in the Preparing
the Meter and Preparing the Probe chapters of this manual.
The user can choose from two sets of pH buffer values for 3-point calibration. The first set
consists of the standard YSI pH buffer values of pH 7 (YSI 3822), pH 4 (YSI 3821) and pH 10
(YSI 3823). The second set available is the NIST pH 6.86, 4.01 and 9.18. Note that the first
calibration point must be either pH 7 or pH 6.86. Calibration is performed as follows:
1.
Turn the instrument on by pressing the ON/OFF key. Press the MODE key until pH is
displayed.
2.
Rinse the probe with deionized or distilled water, then carefully dry the probe (or rinse it with
some of the pH buffer solution to be used for calibration).
3.
Place 30 to 35 mL of the pH buffer you have chosen to calibrate the system with (pH 7 or
6.86) in the 100 mL graduated cylinder (provided with the Model 63). The graduated cylinder
minimizes the amount of solution needed. Immerse the probe making sure that both the pH
and temperature sensors are covered by the solution (see Figure 5 on the following page).
