6 | Operation & Maintenance Instructions FLOWCON | Function
2. Function
FLOWCON is a flow monitoring system comprised of several components specifically
desigened for pulsating flows associated with positive displacement solenoid or mo-
tor-driven dosing pumps. Its function is based on the evaluation of pulsations occuring
typically in the discharged volume flow of dosing pumps. During the discharge stroke a
float element is lifted by the pulsating liquid and thus operates a reed contact. By setting a
switch point, the flow rate determined previously by gauging is monitored. Thus the sensor
is not only sensing, whether the pump is operating, but also whether the preset flow rate is
maintained. Provided that system pressure and fluid viscosity are constant, the repeat-
ability is 10-20%.
A bypass valve allows for the monitoring of a dosing range of 0.05...12 l/h for solenoid-
driven dosing pumps and 1...50 l/h for motor-driven dosing pumps.
The electronic evaluation can be carried out by an on-site PLC, a meter or an electronic
unit, specifically developed for this purpose.
2.1 Evaluation unit FLOWCON
The evaluation unit FLOWCON allows for the monitoring of a dosing pump‘s discharge
volume in an electronic way. Failure or incorrect operation of the dosing pump is indicated
by means of a relay contact.
Monitoring of solenoid-driven dosing pumps
A stroke sensor attached to the pump (refer to MB 1 32 01) registers, when the dosing
pump has carried out a discharge stroke. In the case of accurate dosing this discharge
stroke is confirmed by the reed contact of the FLOWCON flow sensor. As the stroke sensor
senses the stray field of the drive solenoid, it does not matter whether the pump is control-
led internally or externally.
If the pump is triggered by controller or water meter contacts only, it is also possible to
compare the pump control signal with the acknowledgement of the FLOWCON flow sensor.
Monitoring of motor-driven dosing pumps
In the case of motor-driven pumps, the contact of a proximity initiator at the drive eccentric
is compared with the contact of the FLOWCON flow sensor.
The proximity sensor can be omitted if the pump is controlled by external contacts.
The evaluation unit can be set to accept a tolerable number (max. 7) of faulty strokes. Only
after exceeding this number of faulty strokes, an alarm (relay contact) is released.
If the defined number of acceptable faulty strokes is not reached within 128 discharge
strokes, the faulty strokes indicated so far will be cleared. Thus an unnecessary failure
indication is avoided (i.e. 1 faulty stroke / 128 discharge strokes = 0,78% dosing error
rate).
