Merloni Elettrodomestici
DISHWASHER EVO3
Service manual
EN
03-05-20/0
37-54
Language Issue/Edition
Page
5.8
Turbidity sensor
The turbidity sensor was installed in the dishwasher to identify a) the soil level
of the dishes and b) the presence of rinse aid.
The sensor is housed in a sealed polypropylene tube inside a box which is
installed hydraulically in the upper water inlet line. To be precise, it is
physically located between the upper water inlet line of the wash pump and
the concealed heating element. It is connected with a three-way connector. It
works on the basis of an infrared transmitter that emits a light beam that is
captured by the receiver which then sends an analogue signal to the Bit100
timer.
Selecting a programme
Turbidity sensor used to detect soil grade.
During a cycle, namely during the first pre-rinse, the soil level is measured
with the wash pump on.
Depending on the soil level read, the machine will alter the cycle by reducing
or increasing the cycle times and temperatures of the subsequent stages. The
sensor distinguishes 10 different soil levels (there were 4 in mark2 dishwashers).
The maximum turbidity level is equivalent to the most intense cycle while the
clearest reading (ie. water) corresponds to the shortest cycle. The maximum
turbidity level is equivalent to cycles on machines where this sensor is either
inexistent or not connected.
5.9
Use of rinse aid
To control the use of rinse aid the same principle as the turbidity (soil) sensor
is used. Namely, the water is measured 5 seconds before the rinse aid is
dispensed and another reading is taking after (about 1 minute after). The two
readings are compared to see if there is any difference in the quantity of rinse
aid present. Irrespective of the information received, this data is stored to be
displayed at the end of the cycle when the rinse aid LED/light will be turned
on or off.
Turbidity sensor
