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A fluid flow meter is disclosed which can generate both an electrical
and a mechanical representation of flow rate. A first magnet, mounted
within a flow tube, is displaced in response to fluid flow in the
flow tube. A second magnet, mounted outside the flow tube, moves
in response to changes in the magnetic coupling between the first
magnet and the second magnet caused by displacement of the first
magnet within the flow tube. A pointer is coupled to the second
magnet and moves with the second magnet to produce a visual representation
of flow rate. A sensor, mounted in proximity to the second magnet,
and responsive to movement of the second magnet, produces an electrical
signal representative of the flow rate.
A vortex flow meter comprises a first diaphragm which divides first
and second pressure chambers from each other; a second diaphragm
which divides third and fourth pressure chambers from each other
and is disposed in such a manner that the direction in which the
second diaphragm is movable is coincident with that in which the
first diaphragm is movable, and that the direction is not coincident
with that of the maximum component of an external force which acts
on the diaphragms; first and second bridge circuits which make outputs
in response to the action of the first and second diaphragms, respectively;
and differential amplifiers which perform the differential amplification
of the outputs from the first and second bridge circuits.
Fluidic volumetric flow meter method and apparatus wherein undesirable
dynamic interaction (ringing) which could appear in an output signal
is inhibited. Electrical isolation and shielding also contribute
to a high quality output signal in accordance with the invention.
Particularly advantageous housing structures adapt the flow measurement
device to a variety of applications as a complete flow meter.
A part of a tube, through which a fluid passes, is cooled by means
of an electronic cooling element and a flow rate of the fluid is
measured on the basis of a temperature of a surface of the tube
cooled. Not only can the flow rate of the liquid flowing through
the tube be determined in a noncontacting manner and a very small
flow rate of the liquid be determined, but also the tube is cooled
so that no bubbles are generated, and thus the measurment of the
liquid, which is apt to generate gases, such as low boiling point
liquid, is possible. In addition, the measurement is not influenced
by the gases dissolved in the liquid and merely the temperature
difference resulting from the flow of the fluid, that is, the rise
of the temperature of the fluid, is detected to prevent the measurement
from being influenced by the installing posture of the flow meter,
so that a highly accurate measurement is possible. Consequently,
stable and sure controlling flow rate of liquid is possible.
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