The Chemical Curve; Selecting Display Units And Display Decimals - Vaisala K-PATENTS PR-23 Series Instruction Manual

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3. The chemical curve: The Indicating transmitter DTR receives n
culates the concentration value according to chemical curves derived from avail-
able chemical literature and our expertise. The result is a temperature compen-
sated calculated concentration value CALC.
4. Field calibration: Adjustment of the calculated concentration value CALC may be
required to compensate for some process conditions or to fit the measurement to
the laboratory results. The Field calibration procedure, Section 6.4.3, determines
the appropriate adjustment to CALC. The adjusted concentration is called CONC.
If there is no adjustment, CALC and CONC are equal. Thus the chemical curve is
kept intact as a firm base for the calculation, the adjustment is merely additional
terms.
5. Damping: See Section 6.1.
6. Output signal: The range of the 4 to 20 mA signal is defined by its two endpoints
on the CONC scale, see Section 6.3.3.

6.4.1 The chemical curve

The chemical curve is the theoretical concentration curve based on n
defined by a set of 16 parameters (Table 6.1, one set for each sensor).
Table 6.1 The chemical curve parameters
A chemical curve is specific to the given process medium, e.g. sucrose or sodium hy-
droxide. The set of parameters is given by Vaisala and should not be altered, except
in case of changing to another process medium. The parameters can be changed by
selecting first
5 CALIBRATION
CHEMICAL & FIELD PARAMETERS

6.4.2 Selecting display units and display decimals

The display units and display decimals are set separately for each sensor, so first go to
the Calibration menu of the correct sensor. Then select
menu and in the Outputs menu choose either
For the display units, select either
unit. For display decimals, enter the number of decimals you want to see on display
by entering a number in the range 0–5 (0 meaning no decimals are shown).
Note: Change of concentration unit will not change the numerical value of the con-
centration. Change of temperature unit will recalculate the numerical temperature
value according to selected scale (°C or °F).
C C C C
00 01 02 03
C C C C
10 11 12 13
C C C C
20 21 22 23
C C C C
30 31 32 33
from the Main menu, then, in the Calibration menu,
, and finally
1 CHEMICAL CURVE PARAMETERS
1 DISPLAY UNITS
1 CONCENTRATION
PR-23 instruction manual
and TEMP and cal-
D
and TEMP. It is
D
.
in the Calibration
2 OUTPUTS
or
2 DISPLAY DECIMALS
or and then the
2 TEMPERATURE
1
.