The Conductivity Measurement And Control Instrument; Temperature Compensation - Ecolab LMI 02 Notice Technique

5.2

The conductivity measurement and control instrument

The LMI 02 is a conductivity measurement and control instrument which forms - together
with the metering pump and the cleaning tank - a closed loop (see fig 5.2).
It measures the conductivity of detergent solutions with an inductive conductivity probe.
The LMI 02 control compares the measured conductivity value (actual value) with the pre-
set value (set-point value). If the actual value is lower than the set-point value, a metering
pump starts to increase the concentration of the solution.
As soon as the pre-adjusted concentration level is reached approximately, the control
circuit switches over to "pulse-pause-mode" until the pre-adjusted concentration is finally
reached. Therewith higher concentrations (overshoots) are sure disabled.
This control action is repeated if the actual value is lower than the set-point value.
fig. 5.2
5.3

Temperature compensation

Conductivity varies, depending on the temperature of the solution which is to be
determined. The temperature sensor which is installed in the conductivity probe
compensates the influence of the temperature on the measurement result. The temperature
compensation factor can be set to ACID (1,25 %/K) or ALKALINE (1,9%/K).
Recommended settings:
- for alkaline cleaning products:
- for acidic cleaning products:
417102012_LMI02.doc
ALKALINE (1.9 %K)
ACID (1.25%/K) mean value of H
- 59 -
SO und HNO
2 4 3
Rev. 10-01.09