Yokogawa 2-Wire Dual Channel Transmitter/Analyzer FLXA21 - Manual (Page 178)

<15. OPERATION OF SENCOM pH/ORP>
15-9
IM 12A01A02-01E 5th Edition : Oct. 31, 2013-00
Day
Value
Lower limit
Upper limit
Current
date
Projected
maintenance date
F0310.ai
Figure 15.7
The status shows the certainty of the projected maintenance date in terms of the correlation
coefficient R. Tables 15.1 and 15.2 show respective display patterns.
Table 15.1 Display pattern of the projected maintenance date
Projected date - - 0-1 month 1-3 months 3-6 months 6-12 months Over 1 year
- - : cannot be predictable due to insufficient data
Table 15.2 Display pattern of the status
Status
(- - - - -)
(R < 0.50)
(Poor)
(0.50 ≤ R < 0.70)
(Reasonable)
(0.70 ≤ R < 0.85)
(Excellent)
(0.85 ≤ R < 1.00)
n Projected replacement
The projected replacement function predicts the date when the sensor will need replacing for
maintaining the measurement accuracy, based on the pH zero and pH slope on each calibration,
and reference impedance (input-2 impedance) after each calibration. The projected replacement
date is predicted based on these parameters stored upon calibration, and displayed the same as
that of projected maintenance. For details, see the description about the projected maintenance.
Since three parameters (pH zero, pH slope, and input-2 impedance after calibration) are used for
this projection, the nearest coming day is selected as the projected replacement date from the
extrapolated line of the values obtained by the least squares method.
n SENCOM sensor status
The status of the SENCOM sensor is displayed.
Max temp. exposed
Displays the maximum temperature, which is automatically updated every time a higher
temperature is measured.
High pH total time/Low pH total time
Displays the total time during which the pH value remains above the upper pH limit or below the
lower pH limit.
Up to 10 years (87600 hours) can be counted, after which the time is no longer updated. For the
setting of the parameters, see Section 16.2.7.
Sterilization
Displays the number of times the temperature remains above the preset value for at least the
prescribed time period (min.). For the setting of these parameters, see Section 16.2.7.
Figure 15.8 shows an example of sterilization.
15
SENCOM