Notes On Application And Operation; Determining The Measurement Ranges - Endress+Hauser CUS 5 Instructions De Montage Et De Mise En Service

Turbidity sensor CUS 5
4.2

Notes on application and operation

A
20 mA
X
4 mA
1
Response curve
Figure 4.4 displays the response curve of the
sensor CUS 5.
A current signal at the output corresponds to
each concentration value.
The characteristic form of this response curve
results in the same output signal X for the two
different concentrations 1 and 2.
Concentration measurement
If the sensor should be used for continuous
measurement of variable concentrations, then
it must be ensured that the concentration
value corresponds to one of the response
curve branches.
This results in two measurement ranges:
0 ... 5 g/l (A) and 5 ... 40 g/l (B).
4.3

Determining the measurement ranges

Concentration measurement
• Take a sample of the medium with the
highest occurring concentration and
measure the output current of the sensor.
• Dilute the sample in steps until the lowest
occurring concentration is reached. At each
concentration step, track the current output.
• This series of measurements should either
be increasing or decreasing in value.
Endress+Hauser
5 g/l NS*
Turbidity / concentration
2
In order to increase the resolution in the pure
water range, the slope of the sensor response
curve can be changed (broken line in figure)
using a PC with the appropriate software (see
chapter 6.3 Accessories). The position of the
maximum remains unchanged at approx. 5 g/l.
The current value can, however, fall outside of
the range 4 - 20 mA.
Phase limit detection
The confinement to one of the two ranges
is not necessary for operation as a limit
detector. However, it must be ensured that
the same output currents are not the same for
the concentration values of the two media
which are to be descriminated.
Chapter 4.4 illustrates this using specific
examples.
Phase limit detection
• From each occurring medium, or different
phases of the same medium, take a sample
and measure the current output.
• From the resulting current values, you can
observe whether the phases are
distinguishable.
See also the examples in chapter 4.4.
B
40 g/l NS*
4. Commissioning
14US005A.CHP
Fig. 4.4 Response curve CUS 5
*NS = Normal sludge
(1 g/l = appr.. 2400 NTU)
25