Liquid Controls Precision Turbine Flowmeters - Manual (Page 3)

FORWARD
A. PRINCIPLE OF OPERATION
1. The precision turbine flowmeter is a volumetric flow measuring device.
2. The flowing fluid engages the vaned rotor causing it to rotate at an angular velocity proportional to the flowrate.
3. The angular velocity of the rotor results in the generation of an electrical signal (AC sine wave type). Summation
of the pulsing electrical signal relates directly to the flow rate.
4. The differential pressures developed across the turbine flowmeter balances out normal downstream thrust
loads, thus eliminating the need for thrust bearings over the rated range of the meter.
5. The vaned rotor is the only moving part of the flowmeter.
B. PHYSICAL DESCRIPTION
Refer to Assembly procedures in this manual for the identification of major parts of a typical SPONSLER PRECISION
TURBINE FLOWMETER.
C. ELECTRICAL DESCRIPTION
The pickup coil furnished with each SPONSLER PRECISION TURBINE FLOWMETER is a sensing device that
converts the change of magnetic flux from a permanent magnet, produced by the revolving rotor, into an AC sine wave.
Signal amplitude and frequency are directly proportional to flow rate.
1. Pickup Coil Types-
(a) Variable Reluctance- Generating pickups contain a permanent magnet and associated wire-wound coil. The
movement of the ferrous material of the rotor blade past the coil tip disrupts a magnetic field producing an AC
signal within the coil winding.
(b) Inductance-Generating pickups contain a wire-wound coil suitably fixed within a hermetically sealed housing.
The movement of a permanent magnet embedded in a rotor produces an AC signal within the coil winding.
2. Pickup Coil Output- The generated AC sinewave is transmitted via 2 wire shielded cable that minimizes external
interference.
3. Your Pickup Coil- Has been selected to best suit your particular application. The reluctance coil provides the
highest full scale frequency and a lesser signal/noise ratio. The inductance coil has a higher signal/noise ratio
and a lower full scale frequency.
Pg.1