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A liquid flow meter comprises a housing having a cylindrical piston
chamber and a control chamber. A measuring piston is movable in
the piston chamber and a flow control slider is movable in the control
chamber and it has respective oppositely directed control surfaces
which are made effective, by the flow of liquid between the inlet
to the housing and a communication between the measuring piston
chamber and the control chamber to move the control slider in a
control direction. At each end position of the slider, there is
a magnetic holding device for holding the slider until a predetermined
control pressure is brought to bear against it to move it in an
opposite direction. At each limit of its movement, the piston engages
and charges an energy or power storage device operable to accelerate
its movement in the opposite direction. The control movements of
the slider for regulating the flow between the inlet and the outlet
are varied in accordance with the position of the measuring piston.
A rate-of-flow meter, particularly for diagnostic spirometry, comprises
a flow tube containing, on diametrically opposite sides, a measuring
stud provided with pressure taps and a displacement body facing
the stud.
A fluid flow meter of the variable area flow passage type is provided
wherein the variation in said flow passage area is effected by the
vertical displacement of a control boundary which is supported by
a substantially horizontal annular diaphragm element. Said control
boundary is shaped and sized so that the overall displacement required
for the flow rate range desired is within the stroke capacity delivered
by the total, up and down, free flexing action of said diaphragm
element, thereby achieving substantially constant differential pressure
operation at a very reasonable value which is due almost entirely
to gravity. The resulting unit is very compact and stable and is
characterized by very smooth linear response between vertical displacement
and fluid flow rate. Said vertical displacement can be measured
by various means but is preferably transduced to an equally linear,
smooth and steady electrical signal by a direct connection with
a specially adapted differential transformer.
The present invention relates to a magnetic-inductive flow meter
with a measuring tube, which can be fitted into a pipeline system
by using connecting means, with at least two measuring electrodes
that are fitted into the wall of the measuring tube opposite each
other in an electrically isolated manner and are intended for sensing
a measuring voltage, a magnet unit, which is likewise arranged on
the outside of the measuring tube, generating a magnetic field that
is aligned substantially perpendicularly in relation to the direction
of flow of the conductive flow medium to be measured. In order to
provide here a magnetic-inductive flow meter for low-pressure applications
which can be easily produced and can also be easily fitted into
a pipeline system, it is proposed here according to the invention
that the the measuring tube (1) is produced from a semifinished
tube made of high-density polyethylene (HDPE), which can be fitted
into the pipeline system (2) without any flanges.
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