Abstrict A fluid flow meter comprising a flow tube of generally circular
cross section in which is mounted a pair of generally semicircular
vanes arranged for pivotal movement about a common diametral axis,
said vanes being biased by resilient means into positions so as
to close the tube and fluid flow indicating means for measuring
gas flow rates in the range including flare gas flows and furnace
combustion air flows.
Claims I claim:
1. A fluid flow meter comprising
a flow tube having fluid flow input and fluid flow output means,
said tube having a peripheral wall defining a generally circular
flow cross section;
a pair of generally semicircular movable vanes pivotally mounted
within the flow tube about a common fixed diametral axis of said
tube for pivotal movement towards the axial plane containing said
common axis and downstream of said axis;
biasing means coupled to said vanes for urging the latter to pivot
against the fluid flow and in a direction so as to close the said
tube, and
fluid flow indicating means connected to said flow meter, said
fluid flow indicating means serving to indicate the fluid flow through
said flow tube.
2. A fluid flow meter according to claim 1 wherein said fluid flow
indicating means comprises pressure tapping means disposed upstream
and downstream of the said vanes, said pressure tapping means being
adapted for coupling to a pressure differential indicating means.
3. A fluid flow meter comprising:
a fluid flow tube having first and second axial ends, said first
end including fluid flow input means and said second end including
fluid flow output means, said tube having a peripheral wall between
said ends defining a generally circular flow cross section;
a first support means within said tube and between said ends, said
support means being arranged along a diametral axis of the tube
thereby dividing the said flow passage;
a pair of generally semicircular movable vanes hinged on said first
support so as to pivot about the said diametral axis and downstream
of said axis;
second support means mounted within the flow tube upstream of the
said first support means;
respective spring means coupling each said vane to the said second
support means so as to urge said vanes in a direction to close the
tube;
first pressure tapping means provided upstream of said vanes; and
second pressure tapping means provided downstream of said vanes.
4. A fluid flow meter comprising:
a flow tube having a fluid flow input and a fluid flow output means,
said tube having a peripheral wall defining a generally circular
flow cross section;
a pair of generally semicircular movable vanes pivotally mounted
within the flow tube about a common fixed diametral axis of said
tube for pivotal movement towards the axial plane containing said
common axis and downstream of said axis;
biasing means coupled to said vanes for urging the latter to pivot
against the fluid flow and in a direction so as to close the said
tube, and
mechanical means coupled to at least one of said vanes for indicating
angular displacement of said vanes relative to their closed position.
5. A fluid flow meter comprising:
a fluid flow tube having first and second axial ends, said first
end including fluid flow input means and said second end including
fluid flow output means, said tube having a peripheral wall between
said ends defining a generally circular flow cross section;
a first support means within said tube and between said ends, said
support means being arranged along a diametral axis of the tube
thereby dividing the said flow passage;
a pair of generally semicircular movable vanes hinged on said first
support so as to pivot about the said diametral axis and downstream
of said axis;
second support means mounted within the flow tube upstream of the
said first support means;
respective spring means coupling each said vane to the said second
support means so as to urge said vanes in a direction to close the
tube; and
mechanical means coupled to at least one of said vanes for indicating
angular displacement of said vanes relative to their closed position.
Description DISCUSSION OF PRIOR ART
The fluid flows usually encountered with gas flares or the supply
of combustion air to furnaces are usually at low static pressures
and therefore cannot easily be measured, since the pressure drop
across the conventional fluid flow devices is small and the range
of sensitivity is generally only of the order between 100 per cent
and 25 per cent of full scale deflection.
It is a primary aim of this invention to broaden the sensitivity
range of a gas fluid flow meter and it is a further aspect of the
invention to reduce the permanent pressure loss which results from
conventional differential pressure devices for fluid flow measurement.
Accordingly the invention provides a none type fluid flow meter
comprising a flow tube having fluid flow input and fluid flow output
means and a peripheral wall defining a generally circular flow cross
section, a pair of generally semicircular movable vanes pivotally
mounted within the flow tube on a common fixed diametral axis thereof
for pivotal movement towards the axial plane containing said axis
and downstream of said axis, biasing means coupled to said vanes
for urging the latter against the fluid flow and in a direction
so as to close the said tube and fluid flow indicating means. Preferably
the fluid flow indicating means will comprise a pair of pressure
taps arranged respectively upstream and downstream of the vanes,
said taps being connected to a device capable of measuring differential
pressure. Alternatively, the fluid flow indicating means may take
the form of a mechanical linkage coupled to the said vanes.
BRIEF DESCRIPTION OF DRAWING
FIG. 1 is a view partly in section of the flow tube and indicator.
FIG. 2 is a view partly in section of the flow tube with a different
form of indicator.
DESCRIPTION OF EMBODIMENT
In the flow tube 1 a pair of semicircular vanes 2 3 are hinged
for rotation about a diametral pivor 4. The vanes 2 3 are urged
into a position in which they close the tube by springs 5 6 attached
at their first ends to their respective vanes and at their second
ends to a support 7. Pressure taps 8 9 coupled to a diaphragm chamber
10 are mounted respectively upstream and downstream of the said
vanes. the diaphragm chamber 10 contains a diaphragm 11 which is
connected through a linkage 12 to an indicator 13 to co-operate
with a scale 14 which indicates in flow units. Mounting flanges
15 16 are provided at each end of the flow tube 1.
In an alternative arrangement the vanes are coupled directly to
a mechanism for indicating the angular displacement of the vanes
and thereby providing a measure of the fluid flow: see FIG. 2. This
alternative arrangement includes mechanical linkage 20 coaxially
fixed to one of the vanes at one end, and connected to an indicator
21 at the other end. The indicator 21 cooperates with scale 22 which
also indicates in flow units.
The fluid flow meter described herein may provide a direct indication
of flow, relative to the pressure differential measured upstream
and downstream of the vanes, over a measuring range of 100 to 1.
It will be appreciated by skilled workers in the art that alternative
pressure differential measuring devices may be substituted for the
arrangement shown herein, and that known linearizing or characterizing
linkages may be provided on the output of the diaphragm chamber.
It will also be appreciated by those skilled in the art that the
measuring device described herein may also be employed for measuring
liquid flows where a low pressure loss is an advantage. |