Emerson Rosemount FCL, Справочное руководство

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The transmitter doesn't update the calibration. For troubleshooting assistance, see
Troubleshooting when no error message is showing .
11. To return to the main display, press MENU and then EXIT .
6.4 Calibration - pH
6.4.1 Purpose
A pH sensor consists of a glass and reference electrode. Usually, the two electrodes are
combined into a single body, called a combination pH sensor.
When the sensor is placed in an aqueous solution, it produces a voltage proportional to
pH. An ideal pH sensor has a potential of 0 mV in pH 7 solution and a slope of -59.16
mV/pH at 25 °C (77 °F), that is, a unit increase in pH causes the potential to drop 59.16 mV.
However, even in a new pH sensor, the slope and offset are rarely equal to the ideal values.
And, as the sensor ages, the offset typically increases, and the slope decreases. For these
reasons, a new pH sensor should be calibrated before use, and the sensor should be
recalibrated at regular intervals. A pH sensor is calibrated by exposing it to standard
solutions having known pH values. The standard solutions are called buffers.
6.4.2 Definitions
Automatic buffer
calibration In automatic buffer calibration, the transmitter recognizes the buffer
and uses the temperature-corrected pH value in the calibration. The
table lists the buffers the transmitter recognizes. Temperature-pH
data are valid between at least 0 and 60 °C (32 and 140 °F).
Buffer list Buffer pH
Standard
(1)
1.68, 3.56 3.78, 4.01, 4.64, 6.86,
7.01, 7.41, 9.18, 10.01, 12.45
DIN19267 1.09, 3.06, 4.65, 6.79, 9.23, 12.75
Ingold 1.993, 4.005, 7.002, 9.206
Merck 2.002, 4.014, 7.003, 9.004, 12.009
Fisher 1.00, 2.00, 3.00, 4.00, 5.00, 6.00,
7.00, 8.00, 9.00, 10.00, 11.00
(1) With the exception of pH 7.01 buffer, the standard buffers are NIST
buffers.
Reference Manual Calibrate
00809-0100-3412 May 2019
Rosemount FCL 1056 69