Hach-Lange SI794 P User Manual - Manual (Page 67)

67
pH calibration
Calibration is used to adapt the transmitter to the individual
electrode characteristics, namely offset and slope. Calibration
can be performed with Calimatic automatic buffer recognition,
with manual buffer input, by entering premeasured electrode
data, or by sampling the product.
When using ISFET sensors, you must adjust the zero point first.
Then you can conduct either a one or a two-point calibration.
Caution
• All calibration procedures must be performed by trained
personnel. Incorrectly set parameters may go unnoticed, but
change the measuring properties.
• The response time of the electrode and temperature probe is
considerably reduced when the electrode is first moved about
in the buffer solution and then held still.
• The transmitter can only operate properly when the buffer
solutions used correspond to the configured set. Other buf-
fer solutions, even those with the same nominal values, may
demonstrate a different temperature response.
This leads to measurement errors.
When using ISFET sensors or electrodes with a zero point
other than pH 7, the nominal zero point must be adjusted each
time a new electrode is connected. This is important if you want
to obtain reliable Sensoface messages. The Sensoface messages
issued during all further calibrations are based on this basic
calibration.