34
Calibrating the Sensors
6.2 Choosing the Calibration Method
Calibrate the slope by comparing it to a laboratory measurement and set the zero
calibration with either a chemical zero, or with the electrical zero. For most users,
Hach recommends using the Electrical Zero Calibration. An optional chemical
zero cartridge is available. The recommended reference method for a chemical
calibration is DR/2500 AccuVac™ Method (Cat. No. 2505025).
6.3 Choice of Calibration Values
Note:
All results (calibration or
measurements) are normalized to
the reference temperature (25 °C,
77 °F). If the sample's temperature
is different than the reference
temperature, automatic temperature
compensation will correct the value.
However, sufficient time must be
allowed for the sensor to reach
temperature equilibrium.
In processes that have significant variations in chlorine concentration, i.e.,
in a water tower, the calibration point should be found in the upper values rather
than in the lower values. This maximizes the precision of the apparatus.
Any imprecision in the comparison measurement will be reflected in the calibrated
measurements made by the instrument. Avoid this by using a reliable
comparison method.
6.4 Calibrating the Hydrazine Sensor
6.4.1 Electrical Zero Calibration
1.
From the Main display, push the
RIGHT ARROW
key.
2.
Use the
LEFT ARROW
key to highlight CALIBRATION. Press
ENTER
.
3.
Use the
LEFT ARROW
key to highlight CONC. CALIB. Press
ENTER
.
4.
Use the
LEFT ARROW
key to highlight ZERO. Press
ENTER
.
5.
Press
ENTER
to select PROGRAMMING.
6.
Use the
RIGHT ARROW
key to highlight ELECAUTO. Press
ENTER
.
7.
Press the
ESC
key once.
19
66.2
292.15
42
107.6
315.15
20
68
293.15
43
109.4
316.15
21
69.8
294.15
44
111.2
317.15
22
71.6
295.15
45
113
318.15
Table 11 Temperature Conversions (continued)
°C
°F
K
°C
°F
K
