Teledyne LXT-230 manual 6.4Two-PointBuffer Calibration Span, Procedure

Procedure:

1.Press the appropriate MENU SELECTION key to reach the Electrode Standardization Menu and locate the cursor under the "1" as illustrated in section 3.2.4.

2.For diagnostic reasons note the pH and mV values from the prior calibration.

3.Clean the electrode and insert the sensor into the desired buffer.

4.Press both horizontal CALIBRATE keys simultaneously to enter the calibrate mode. Observe the diagnostic value on the bottom line change from historical data to a real-time value and that the term "CAL" has disappeared.

1 pH	7.00
	-3.2 mV@25

1 ORP	.0 mV
	85.9 mVa

5.To change the buffer point, position the cursor under the desired digit using the left- hand CALIBRATE key.

6.Increase or decrease the value by pressing the appropriate vertical CALIBRATE key.

7.Wait for the real-time mV value to stabilize.

8.To file the calibration and exit the calibrate mode, press either MENU SELECTION key.

6.4Two-Point Buffer Calibration (Span)

When first installing an electrode, a two-point buffer calibration should be used to compensate for electrode slope variations or efficiency.

Procedure:

1.Perform a one-point calibration as outlined in section 5.3.

2.Press the appropriate MENU SELECTION key to reach the Electrode Span Menu and locate the cursor under the "2" as illustrated in section 3.2.5.

3.For diagnostic reasons note the pH and mV values from the prior calibration.

4.Press both horizontal CALIBRATE keys simultaneously to enter the calibrate mode. Observe the diagnostic value on the bottom line becomes a real-time value and that the term "CAL" has disappeared.

2 pH	4.00
	-58.2 mV/pH

2 ORP	180.0 mV
	.980 mV/ORP

5.To change the buffer point, position the cursor under the desired digit using the left- hand CALIBRATE key.

6.Increase or decrease the value by pressing the appropriate vertical CALIBRATE key.

7.Wait for the real-time mV value to stabilize.

8.To file the calibration and exit the calibrate mode, press either MENU SELECTION key.

A perfect electrode slope (efficiency) is -59.1 mV/pH and ORP is 1mV/mV. If the value falls below -50.0 mV/pH or ORP .9 mV/mV, the electrode should be serviced or replaced.

IMPORTANT

If a flashing asterisk appears during or after calibration, the electrode may require service, or the buffer solution may be contaminated. Refer to section 5.6 for details.

NOTE:

Comparing the millivolt values before and after the calibration provides a valuable

Model LXT-230 Instruction Manual / 14