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MODEL 6081-P pH/ORP SECTION 10.0
CALIBRATION – PH
FIGURE 10-1. Calibration Slope and Offset
During automatic calibration, the transmitter also measures
noise and drift and does not accept calibration data until read-
ings are stable. Calibration data will be accepted as soon as the
pH reading is constant to within the factory-set limits of 0.02 pH
units for 10 seconds. The stability settings can be changed.
In manual calibration, the user judges when pH readings are
stable. He also has to look up the pH of the buffer at the
temperature it is being used and enter the value in the transmitter.
Once the transmitter completes the calibration, it calculates the
calibration slope and offset. The slope is reported as the slope
at 25°C. Figure 10-1 defines the terms.
The transmitter can also be standardized. Standardization is the
process of forcing the transmitter reading to match the reading
from a second pH instrument. Standardization is sometimes
called a one-point calibration.