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I
MPORTANT
I
NFORMATION
O
PERATING
P
RINCIPLE
Fluid passing through the meter causes the rotors to turn, as shown in the image below.
One of the rotors (the active rotor) is fitted with magnets. As the rotors turn, the passing magnet is picked up by a
Magnetic Sensor (either Reed and Hall Effect sensors) located on the Pulser Circuit Board.
The excitation of these sensors provides a ‘Raw Pulse Output’ which relates to a designated K-Factor according
to meter model. The K Factor is the number of pulses (rotations) per unit volume of fluid (e.g. Litres or Gallons)
(e.g. K Factor of 36 translates to there being 36 pulses for every litre of fluid that has passed through the
flowmeter)
This Pulse Output Signal can either be fed directly to an external receiving device (e.g. Data Logger or PLC) or
alternatively to an LC Display, which then conditions the raw pulse input signal to display volume of fluid passed.
(e.g. Displays 1 Litre for every 36 pulses received
)
The ‘Active Rotor is
fitted with magnets
Flow Direction
It is recommended the Reed Switch is used with low supply voltage applications up to 12VDC
The reed switch can cause inaccurate rate counts when used with high speed counters.
It is advised that a low speed counter is used or alternatively a de-bounce circuit be installed.
Reed Switch
NPN Open Collector Hall Effect Sensor
Suitable for supply voltage applications exceeding 12VDC
The output for the hall effect sensor is NPN (current sinking, open collector). For correct operation, it is advisable to have a
pull-up resistor installed.
The hall effect sensor is equipped with a 1k8
Ω
pull-up resistor between signal and supply as standard.
This in-built pull-up resistor can be bypassed by moving the jumper pin to the off position if required.
A pull-up resistor of your choosing can be installed between signal and supply, provided the in-built pull-up resistor be
bypassed first.
