Operational Procedures; Buffer Set Selection; Ph Calibration; Atc/Temp Probe, Ph-Autolock Mode - ECD L20 Instruction Manual

Operational Procedures

A. Buffer Set Selection
The Model L20 meter has two buffer sets: 7.00, 4.01, 10.01pH and 6.86,
4.00, 9.18 pH. The meter is factory pre-set at 7.00, 4.01 and 10.01 pH. To
change the buffer set, turn off the unit, then press and hold the "Stand"
key while turning on the unit again.
[Note: There is no need to repeat this procedure every time the unit is
power up unless one decides to change the buffer settings.]
B. pH Calibration
The Model L20 uses 2-point or 3-point calibration. The first point must be
6.86/7.00, and the second point can either be 4.00/4.01 or 9.18 / 10.01.
a. Calibration with an ATC/Temp probe in the pH-AUTOLOCK mode
1. Turn the unit on. Press "Clear" key for 2 seconds, all LCD elements
will light up. The meter clears all calibration values stored in internal
memory.
2. Connect the pH electrode to the BNC connector and the ATC/Temp
probe to the ATC/Temp connector of the unit: "ATC" icon will light
up. "pH" icon and "AUTO" icon light up. The buffer set icon will flash.
3. Rinse the pH and ATC/Temp probes in distilled water and immerse
them in the first buffer solution (either 7.00 or 6.86). Allow
temperature reading to stabilize, then press and hold "Stand" key
for 5 seconds to calibrate. The "WAIT" icon will flash until the unit
detects a stable reading. Once the unit calibrates the first point, the
selected buffer remains lit up while the remaining two buffers start
to flash. The unit is ready to be sloped at the second buffer.
[Note: If the first buffer solution is 7.00 or 6.86, at this moment,
press the "Mode" key. The unit will exit the calibration mode. Single
point calibration is complete. If the first buffer solution is 4.00, 4.01,
9.18 or 10.00, at this moment, the unit will automatically exit the
calibration mode. Single point calibration is complete.]
4. Rinse the pH and ATC/Temp probe in distilled water and immerse
them in the second buffer solution (either 4.00/4.01 or 9.18/10.01).
Allow temperature reading to stabilize, then press "Slope" key to
calibrate. The "WAIT" icon will flash until the unit detects a stable
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