Abstrict A mass flow meter device utilizing a housing having a wall portion
forming a chamber with an entrance and exit for passing fluid through
the same. A body is located within the chamber and is composed of
a first conical portion, a second conical portion, and a cylindrical
portion positioned intermediate the first and second conical portions.
The body is held within the chamber in a standard or reverse direction.
A first pressure probe or sensor measures the fluid pressure at
the apex of the first conical portion while a second pressure probe
or sensor obtains a second pressure measurement at the cylindrical
portion of the body. The comparison of the first and second pressure
measurements serves as an indication for the mass flow of fluid
through the housing. The flow meter device may be adapted to existing
fluid sources such as aerosol generators.
Claims What is claimed is:
1. A fluid mass flow meter device, comprising: a. a housing having
a wall portion forming a chamber, said chamber possessing an entrance
and an exit for passing fluid through said chamber; b. a body located
in said chamber said body including a first conical portion having
a base and an apex positioned adjacent said chamber entrance, a
second conical portion having a base and an apex positioned adjacent
said chamber exit, and a cylindrical portion intermediately positioned
relative to said first and second conical portions, said cylindrical
portion having a first base and a second base, said base of said
first conical portion lying against said first base of said cylindrical
portion to orient said apex of said first conical portion toward
said chamber entrance to contact fluid entering said chamber, said
base of said second conical portion lying against second base of
said cylindrical portion to orient said apex of said second conical
portion toward said exit of said chamber to contact fluid passing
through said chamber, said apexes of said first and second conical
portions being free to directly contact fluid in said chamber; c.
support means for holding said body within said chamber; d. a first
pressure probe, said first pressure probe obtaining a first pressure
measurement at the apex of said first conical portion of said body;
and e. a second pressure probe, said second pressure probe obtaining
a second pressure measurement at said cylindrical portion of said
body.
2. The device of claim 1 in which said housing wall comprises a
right circular cylinder having a central axis, said body lying along
a central axis, said central axis of said body being coincident
with said central axis of said right circular cylinder.
3. The device of claim 1 in which said wall portion of said housing
further includes an outer surface and an inner surface surrounding
said chamber and said support means for holding said body in said
chamber comprises a projection depending from and connected to said
inner surface of said housing.
4. The device of claim 1 in which said first and second pressure
probes include a first and second passageway, respectively through
said support means.
5. The device of claim 4 in which said support means comprises
a projection depending from said inner wall of said housing.
6. The device of claim 4 in which said first and second passageways
each terminate in an aperture within said housing chamber.
7. The device of claim 6 in which said aperture of said first passageway
faces said entrance to said chamber and said aperture of said second
passageway faces said exit to said chamber.
8. The device of claim 6 in which said aperture of said second
passageway faces said entrance to said chamber and said aperture
of said first passageway faces said exit to said chamber.
9. The device of claim 1 in which said body with said chamber is
formed into an annulus for the, passage of fluid therethrough.
10. The device of claim 9 in which said housing wall comprises
a right circular cylinder having a central axis, said body lying
along a central axis, said central axis of said body being coincident
with said central axis of said right circular cylinder.
11. The device of claim 9 in which said wall portion of said housing
further includes an outer surface and an inner surface surrounding
said chamber and said support means for holding said body in said
chamber comprises a projection depending from said inner surface
of said housing.
12. The device of claim 9 in which said first and second pressure
probes include a first and second passageway, respectively through
said support means.
13. The device of claim 12 in which said support means comprises
a projection depending from and connected to said inner wall of
said housing.
14. The device of claim 12 in which said first and second passageways
each terminate in an aperture within said housing chamber.
15. The device of claim 14 in which said aperture of said first
passageway faces said entrance to said chamber and said aperture
of said second passageway faces said exit to said chamber.
16. The device of claim 1 which additionally comprises ventilation
means for permitting fluid to enter said chamber of said housing
other than through said chamber entrance.
17. The device of claim 16 in which said ventilation means comprises
a rotatable member rotating relative to said housing wall portion,
a first opening through said wall portion, and a second opening
through said rotatable member, said first and second opening being
alignable by rotation of said rotatable member.
18. A fluid flow modifying device employed in combination with
a source of fluid moving at a certain velocity, and a generator
having a fixture possessing a fluid exit, comprising: a. a housing
having a wall portion forming a chamber, said chamber possessing
an entrance and an exit for passing the fluid through said chamber,
said entrance of said housing linking with the generator fixture
to permit communicating between the fluid source exit and said housing
entrance; and b. a body located in said chamber said body including
a first conical portion having a base and an apex positioned adjacent
said chamber entrance, a second conical portion having a base and
an apex positioned adjacent said chamber exit, and a cylindrical
portion intermediately positioned relative to said first and second
conical portions, said cylindrical portion having a first base and
a second base, said base of said first conical portion lying against
said first base of said cylindrical portion to orient said apex
of said first conical portion toward said chamber entrance to contact
fluid entering said chamber, said base of said second conical portion
lying against second base of said cylindrical portion to orient
said apex of said second conical portion toward said exit of said
chamber to contact fluid passing through said chamber, said apexes
of said first and second conical portions being free to directly
contact fluid in said chamber.
19. The device of claim 18 which additionally comprises means for
determining the pressure at first and second places on said body
with said housing chamber.
Description BACKGROUND OF THE INVENTION
The present invention relates to a novel and useful fluid mass
flow metering device.
Mass flow meters are often used in conjunction with other mechanical
entities such as micro-atomizers, oxygen delivery systems, valve
controlled devices, pressure regulators, compressors, and pumps.
In the past, mass flow meters have taken various forms. For example,
the coriolis system requires high pressures to operate and is limited
by the density of the fluids being measured. Coriolis measurement
devices are also very expensive to manufacture since they require
adjunct devices and computers to determine density. Also, coriolis
flow meters do not measure low-density gases in a reliable manner
and require high pressure to operate.
Non-intrusive magnetic flow meters, although not interfering with
the flow being measured, require an enormous amount of electronic
equipment to measure the magnetic field change of a fluid, based
on magnetic flux. Also, a magnetic medium, such as powdered metal,
must be placed in the fluid to amplify sensitivity of this system.
Doppler sonic effect flow meters, again, are non-obtrusive, however,
and associated density determining mechanisms are required to measure
flow in a conduit are extremely complicated and expensive.
Thermal mass meters employ a bypass capillary heating system relative
to the main flow conduit. In this regard, the capillary mechanism
must be maintained in an extremely clean condition. Also, determination
of the exact type and density of the fluid being measured is a prerequisite
to accurate measurements. In addition, thermal mass meters are very
expensive to manufacture and maintain.
In the past, objects of a defined shape have been placed in conduits
to effect the fluid flow. For example, U.S. Pat. 4812049 describes
a fluid dispersing means in which a cone like member is placed in
a conduit or pipe to disperse fluid component by creating turbulent
flow downstream from the element.
U.S. Pat. Nos. 5363699 and 5814738 describe fluid flow meters
in which flow measurements are taken along a conduit in conjunction
with one or more displacement members.
U.S. Pat. No. 4638672 teaches a fluid flow meter where a fluid
flow member of double conical configuration is placed in the fluid
to determine the velocity profile. Fluid is passed through an auxiliary
flow tube in order to affect measurement by a flow meter.
A fluid mass flow metering device which produces accurate measurements
over a wide range of fluid flow rates would be a notable advance
in the field of measuring instruments.
BRIEF SUMMARY OF THE INVENTION
In accordance with the present invention a novel and useful mass
flow meter device is herein provided.
The device of the present invention uses a container or housing
having a wall portion forming a chamber. The chamber possesses an
entrance and an exit for the passing of fluids therethrough. The
housing is preferably a hollow circular cylinder flow tube with
a circular cross-sectional configuration. The housing may include
appropriate fittings to communicate with a source of fluid and an
exit conduit for the fluid following measurement.
A module or body is located in the chamber of the housing. The
body includes a first conical portion positioned adjacent the chamber
entrance, a second conical portion positioned adjacent the chamber
exit, and a cylindrical portion intermediately positioned relative
to the first and second conical portions. The body is formed as
a unitary member and may be machined or fashioned from a unitary
mass or blank of material. The body is formed to lie along an axis
which coincides with the central axis of the housing when the housing
is formed into a cylindrical tube. In essence, the body fashions
the chamber into an annulus having a relatively large flow passage.
Support means is also found in the present invention for holding
the body in a coaxial configuration, with the housing noted above,
within the chamber of the housing. Such support means may take the
form of a pylon or pedestal which is connected to an inner wall
portion of the housing and depends therefrom. The pedestal is formed
in a sleek configuration to minimize its effect the fluid flow through
the chamber.
A first pressure probe or sensor is employed to obtain a pressure
measurement at the apex of the first conical portion of the body
facing the entrance to the chamber of the housing. The first pressure
probe includes a passageway through the housing, the pylon, and
a portion of the body. The passageway terminates in an aperture
at the apex of the first conical portion of the body to obtain a
dynamic pressure reading at this point. A second pressure probe
also passes through the wall of the body, and the pylon and terminates
in an aperture to obtain a pressure measurement adjacent the cylindrical
portion of the body. The passageways of the first and second pressure
probes each lead to a conventional sensor which provides a numerical
value of the pressure in the chamber of the housing at the points
noted. Each pressure reading on the body located in the chamber
of the housing represents a dynamic pressure due to a stable vortex
trail which is generated by the body located in the chamber. The
flow body may be positioned in a "reverse orientation"
within the housing chamber such that he first conical portion faces
the exit thereof. Accurate mass flow determinations may be obtained
with the flow body lying in this reverse orientation. The flow of
fluid through the chamber and around the body within the chamber
is believed to be streamline and smooth.
The pressure readings, P.sub.1 and P.sub.2 are representative
of the quantitative and qualitative characteristics of the fluid
flowing through the chamber of the housing. Plotting of the difference
between the pressure readings, P.sub.1 -P.sub.2 to known mass flows
through the chamber of the housing results in a graph or table for
a particular fluid i.e. air, argon, water, alcohol, and the like,
at particular temperatures and pressures, with respect to a particular
sized housing, body within the housing, and the annulus through
the chamber. The difference in the pressure readings, P.sub.1 -P.sub.2
may be automatically determined by a comparator and translated into
a determination of mass flow by a proper algorithm.
In certain cases a fluid flow device may be employed as a retrofitted
item to measure mass flow. In such instances a housing containing
the flow body above described may be fitted into an in-line or tapped
line fluid exit. Again, the P.sub.1 -P.sub.2 differential would
serves as a basis for mass measurements which may be performed automatically
and instantaneously. In addition, such retrofitting may alter the
fluid exit flow as well as measuring the mass flow. For example,
medical and non-medical aerosol delivery systems may be retrofitted
to slow and enhance the egressing aerosol.
It is therefore an object of the present invention to provide a
mass flow meter device which operates with minimal components and
provides accurate and repeatable measurements.
Another object of the present invention is to provide a fluid mass
flow meter device which consistently obtains mass flow measurements
through a large range of fluid velocities in a flow stream being
measured.
A further object of the present invention is to provide a fluid
mass flow meter device which closely controls the flow patterns
of fluids and generates a stable, streamline, vortex trail to achieve
such results.
Yet another object of the present invention is to provide a fluid
mass flow meter device which minimizes viscous friction effects,
boundary layer effects, and exhibits Reynolds number immunity.
Another object of the present invention is to provide a fluid mass
flow meter device which is efficient and inexpensive to manufacture
and operate.
Another object of the present invention is to provide a fluid mass
flow meter device which is not affected by external vibration, noise,
or the influence of gravity during its operation.
Another object of the present invention is to provide a fluid mass
flow meter device which is not substantially upset by compressibility
effects or back pressure changes.
A further object of the present invention is to provide a fluid
mass flow meter device which is not substantially prohibited from
obtaining accurate measurements by unstable flow distortions, such
as "vena contracts" or vortex shedding, which affect conventional
volumetric flow meters.
Another object of the present invention is to provide a fluid mass
flow meter device which does not require restrictive contours, flow
areas or orifices to operate.
Another object of the present invention is to provide a fluid mass
flow meter device which does not require the use of flow condition
dependent mathematical adjustment coefficients to its measurements
in order to obtain accurate mass flow determinations.
Another object of the present invention is to provide a fluid mass
flow meter device which does not require the generation of a magnetic
field or minimum fluid pressures in order to operate effectively.
Another object of the present invention is to provide a fluid mass
flow meter device which is relatively inexpensive to manufacture
and function.
A further object of the present invention is to provide a fluid
mass flow meter device which may be used to measure mass flow in
liquids or gases.
A further object of the present invention is to provide a fluid
mass flow meter device which includes a flow body which generates
a pressure differential and which may be positioned in standard
and reverse orientations with a flow chamber.
Another object of the present invention is to provide a fluid mass
flow meter device which does not require preconditioning of the
inlet stream by adding lengths of conduit, providing anti-swirl
mechanisms and the like.
Another object of the present invention is to retrofit a fluid
mass flow meter to existing fluid systems in order to determine
mass flow.
A further object of the present invention is to retrofit a fluid
mass flow device to medical and non-medical aerosol systems to measure
mass flow and to slow and enhance the aerosol.
The invention possesses other objects and advantages especially
as concerns particular characteristics and features thereof which
will become apparent as the specification continues.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
FIG. 1 is a front elevational view of the device of the present
invention.
FIG. 2 is a rear elevational view of the device of the present
invention.
FIG. 3 is a side elevational view of the device of the present
invention with the pressure sensors depicted in broken configuration
and the body of the device being rotated downwardly from the renditions
of FIGS. 1 and 2.
FIG. 4 is a sectional view taken along line 4--4 of FIG. 1.
FIG. 5 is a schematic flow diagram depicting the process employed
in determining mass flow with the device of the present invention.
FIG. 6 is a graph depicting the mass flow determination flow results
using the device of the present invention with air and argon gases.
FIG. 7 is a graph representing the mass flow determinations described
in Example II.
FIG. 8 is a graph depicting the data of FIG. 7 in which each of
the measured P.sub.1 -P.sub.2 values are shown as the square root.
FIG. 9 is a graph depicting the mass flow determinations described
in Example II.
FIG. 10 is a graph depicting the data of FIG. 9 in which each of
the measured P.sub.1 -P.sub.2 values are shown as the square root.
FIG. 11 is a sectional view of the device of the present application
in which the flow body orientation is reversed within the flow chamber
from the orientation of FIG. 4.
FIG. 12 is a graph depicting the mass flow determinations described
in Example III.
FIG. 13 is a graph depicting the data of FIG. 12 in which each
of the measured P.sub.1 -P.sub.2 values are shown as the square
root.
FIG. 14 is a graph depicting the mass flow determinations described
in Example III with the device illustrated in FIG. 11.
FIG. 15 is a graph depicting the data of FIG. 14 in which each
of the measured P.sub.1 -P.sub.2 values are shown as the square
root.
FIG. 16 is a sectional view of the device of the present invention
being used with an orifice plate, described in Example IV.
FIG. 17 is a graph representing the measurements of Example IV.
FIG. 18 is a graph representing the measurements of Example IV.
FIG. 19 is a side elevational view of another embodiment of the
device of the present invention retrofitted to a medical aerosol
delivery system.
FIG. 20 is a partial exploded side elevational view of the prior
art aerosol delivery system and the flow modifying device of the
present invention.
FIG. 21 is a view taken along line 21--21 of FIG. 20.
FIG. 22 is a view taken along line 22--22 of FIG. 20.
FIG. 23 is a sectional view taken along line 23--23 of FIG. 20.
For a better understanding of the invention reference is made to
the following detailed description of the preferred embodiments
thereof which should be taken in conjunction with the prior described
drawings.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
Various aspects of the present invention will evolve from the following
detailed description of the preferred embodiments thereof which
should be referenced to the prior delineated drawings.
A preferred embodiment of the present invention is shown in its
entirety and is noted by reference character 10 in the drawings,
followed by an upper case letter to denote various embodiments of
the present invention. Fluid mass flow metering device 10A includes
as one of its elements a housing 12 which is illustrated as a cylindrical
tube and may be constructed of any rigid or semi rigid material.
Tube 14 possesses a wall portion 16 having an outer surface 18 and
an inner surface 20. Wall portion 16 forms a chamber 22 which possesses
an entrance 24 and an exit 26 defined by the normal passage of
fluids through chamber 22. Directional arrows 28 and 30 of FIG.
1 as well as directional arrows 32 and 34 of FIG. 2 illustrate
the movement of fluid through and from chamber 22 via entrance 24
and exit 26 during the measuring process of device 10A. Cylindrical
tube 14 serving as containment or housing 12 lies along central
axis 36. Cylinder tube 14 is also provided with end fittings 38
and 40 to allow interconnection to a source of fluid and to a conduit
or like entity directing fluid away from device 10. Device 10A is
intended to determine mass flow of liquids or gases which will be
discussed in more detail as the specification continues.
Device 10A also entails the utilization of a flow body 42. Although
flow body 42 is generally a unitary member, flow body 42 includes
three portions. First conical portion 44 of flow body 42 faces entrance
24 of chamber 22. Second conical portion 46 faces exit 26 of chamber
22. First and second conical portions 44 and 46 respectively, includes
converging side portions at about a forty-five degree angle. However,
other angles may be employed with respect to first and second conical
portions 44 and 46. Cylindrical portion 48 lies intermediate first
conical portion 44 and second conical portion 46. The bases of first
conical portion 44 and second conical portion 46 are of the same
diameter, in the embodiment depicted in the drawings, and is similar
the circular top and base of cylindrical portion 48. The result
is a smooth outer surface 49 which produces steady vortex trail.
Flow a body 42 and tube 14 create an annulus configuration of chamber
22 through which the fluid being measured by device 10 travels.
The cross-sectional area of chamber 22 is predetermined ("equivalent
area" or "equivalent diameter") to maximize the operation
of device 10A.
Flow body 42 is supported in chamber 22 by support means 50. Support
means 50 may take the form of a appendage or pylon 52 which extends
inwardly toward axis 36 and is connected to wall portion 16 specifically
inner surface 20 thereof. Pylon 52 is relatively slim compared to
flow body 42 within chamber 22.
A first pressure sensor or probe 52 FIGS. 3 and 4 includes a
passageway 54 which originates in boss 56 fixed to outer surface
18 of cylindrical tube 14. Passageway 54 extends through wall portion
16 of tube 14 pylon 52 and first conical portion 44 of flow body
42. Passageway 54 terminates in a aperture 58 the apex 55 of first
conical portion 44 which faces entrance 24 of chamber 22. Directional
arrow 60 indicates the flow of fluid to aperture 58 which produces
pressure reading P.sub.1. Of course, pressure probe 52 also includes
conventional instruments which quantifies pressure measurement P.sub.1.
Likewise, second pressure sensor or probe 62 is formed with a passageway
64 that extends through boss 56 wall portion 16 of tube 14 and
a portion of pylon 52. Aperture 66 in pylon 52 faces exit 26 and
measures the pressure, P.sub.2 at cylindrical portion 48 of flow
body 42. Dynamic pressure measurements, P.sub.1 and P.sub.2 result
from the stable and smooth vortex trail generated by flow body 42.
Again, directional arrows 68 and 70 FIG. 4 indicate the flow of
fluid through chamber or annulus 22 during the measuring process
employed with device 10.
Dynamic pressures P.sub.1 and P.sub.2 are theorized to follow the
following equations:
where .rho.=the density of fluid measured, and V=the velocity the
fluid measured the velocity differential across device 10 is given
as:
Where A.epsilon. is the equivalent area of chamber 22.
where d.epsilon. is the equivalent diameter of chamber 22.
Since the velocity is squared in the Dynamic Pressure equation
above, the pressure differential value, P.sub.1 -P.sub.2 is dominated
by the fourth power of the equivalent diameter.
In operation, with reference to FIG. 5 a fluid source 72 feeds
housing 12 of device 10A, specifically through chamber or annulus
22 of cylindrical tube 14. Cylindrical body 42 creates a smooth
stable vortex trail and generates dynamic pressures P.sub.1 and
P.sub.2 by the way of pressure probes 52 and 62. Such "vortex
generated differential pressures" are quite prominent and easily
readable by conventional pressure sensors. The difference between
pressures P.sub.1 and P.sub.2 are then determined either manually
or automatically and, through the use of tables or graphs determine
the mass flow of fluid through device 10. That is to say, for a
particular pressure differential, P.sub.1 -P.sub.2 by employing
a particular sized housing 12 with chamber or annulus 22 and at
a particular ambient pressure and temperature, a flow rate is measured,
correlated, and recorded for future use.
The following example represents a particular aspect of the present
invention but is not intended to restrict the invention in any manner.
EXAMPLE I
The device 10A as shown in FIGS. 1-4 was employed to determine
the mass flows of the gases air and argon at room temperature and
at atmosphere pressure. Argon is known to be 1.4 times as heavy
as air and was employed for the sake of comparison. Device 10A was
connected to a pair of pressure sensors, Model No. 860 manufactured
by Autotran Incorporated of Eden Prairie, Minn. The pressure sensors
were then used to determine P.sub.1 and P.sub.2 at the aperture
58 of passageway 54 and the aperture 66 of passageway 64 respectively,
FIG. 4. The mass flow in pounds per second was then determined by
flow rates traced through device 10A and correlated to the pressure
differential, P.sub.1 -P.sub.2. FIG. 6 represents the results of
these tests for air and argon. Thus, for a particular sized housing,
flow body 42 and chamber or annulus 22 a curve or slope was plotted
for each gas. It was concluded that the curves may be extrapolated
or interpolated to produce values of mass flow of either gas for
a particular pressure differential, P.sub.1 -P.sub.2.
EXAMPLE II
Additional testing of the system of the present invention was accomplished
using a Sensym pressure sensor employing the embodiment 10A of the
device depicted in FIG. 1. The sensor was not temperature or pressure
compensated and required average readings based on an up and down
pulsation at any setting. However, consistent measurements were
obtained since such pulsations were stable. Such temperature and
pressure variations are believed to cause errors ranging from 15
to 16 percent. In addition, the anemometer of the Sensym pressure
sensor possesses an accuracy of plus or minus three percent of full
scale.
Using a flow body 42 supported in a housing 12 identified as a
0.500-0.400 plastic unit, the mass flows for air were calculated
in relation to various P.sub.1 -P.sub.2 values, referred to as AP.
The 0.500-0.400 plastic unit possessed an open cross-section area
of about 36 percent. The pressure was measured as inches of water
column. FIG. 7 represents the results obtained over various mass
flow values. The vortex pressure generated P.sub.1 -P.sub.2 values
were then modified or transformed into values of the square root
and plotted against the same mass flows as found in FIG. 7. As may
be seen a linear relationship is established using the modified
or transformed P.sub.1 -P.sub.2 values (MOD. P.sub.1 -P.sub.2).
Reducing the flow with the identical unit (0.500-0.400 plastic
flow body) the flow was reduced to a very low level. The results
were plotted in FIG. 9 between P.sub.1 -P.sub.2 and mass flow. FIG.
10 represents the same linear relationship achieved in FIG. 8 when
the P.sub.1 -P.sub.2 values are modified by taking the square root
of the same. Thus, it was concluded that the square root of the
P.sub.1 -P.sub.2 value versus the mass flow of the fluid through
device 10A represents a linear relationship and produces a very
predictable extrapolation and interpolation for values lying along
the line depicted in FIGS. 8 and 10. It should be noted that no
preconditioning of the air passing through device 10 was employed
to obtain the results depicted in FIGS. 7-10.
EXAMPLE III
The testing described in Example II was again conducted using device
10A having a flow body identified as a 0.750-0.375 plastic unit.
The cross-sectional area of the flow body of 0.750-.375 unit relative
to the cross-sectional area of the chamber 22 of housing 12 produces
an open area of greater than 70 percent. Air was passed through
device 10A with the 0.750-0.375 flow body and the results were calculated
in FIGS. 12 and 13 as a comparison between mass flow and P.sub.1
--P.sub.2. In this "standard direction" the curved graph
result of FIG. 12 was transformed into a straight line, again, by
taking the square root of the P.sub.1 -P.sub.2 values. This result
is shown in FIG. 13.
Referring now to FIG. 11 the flow body 42 was reversed such that
opening 55 faced exit 26 of chamber 22 and opening 66 faced entrance
24 to chamber 22. This "reverse direction" orientation,
device 10B, was then employed in the same manner as described hereinabove
in the present Example. FIGS. 14 and 15 represent the mass flow
determinations from the P.sub.1 -P.sub.2 values and the modified
P.sub.1 -P.sub.2 values described in Example II. It was concluded
that the device of the present invention operates satisfactorily
in either the "standard direction", device 10A as depicted
in FIG. 4 or in the "reverse direction", device 10B as
depicted in FIG. 11.
EXAMPLE IV
Compressibility effects were investigated by using device 10 of
the present invention. In addition, an orifice plate 80 was placed
within chamber-22 having an orifice 82 of a certain size. A 0.750-0.375
steel flow body 42 described in the prior Examples, was employed.
The orifice opening 82 was set at 0.2 inches. FIG. 17 represents
the mass flow versus P.sub.1 -P.sub.2 results which resulted in
a smooth curve. Modifying the P.sub.1 -P.sub.2 values by taking
the square root of each P.sub.1 -P.sub.2 value resulted in a straight
line.
A 0.500-0.400 plastic flow body 42 was then substituted and the
orifice opening 82 was set at 1/8 of an inch. FIG. 18 represents
the values obtained for mass flow versus P.sub.1 -P.sub.2 in this
instance. Again, a smooth curve was obtained which is easily transformed
into a straight line by taking the square root of each of the P.sub.1
-P.sub.2 values, as was performed in the heretofore delineated Examples.
The measurements of this Example represents little or no compressibility
effects due to backpressure provided by the orifice plate 80 and
the orifice 82 thereof. Surprisingly, the temperature at the beginning
of both runs was approximately 75.degree. F. while at the end of
the run the temperature was 120.degree. F. Again compressibility
corrections for temperature were not needed to provide the results
shown in FIGS. 17 and 18.
Referring now to FIG. 19 another embodiment 10C of the present
invention is depicted. Embodiment 10C represents an application
of the flow device as depicted in embodiments 10A and 10B in a retrofit
application. In this regard, device 10C represents the ability to
measure mass flow in many environments. For example, the present
invention may be employed to measure mass flow in medical gas modules,
oxygen lines, oxygen masks, medical appliances such as nebulizers,
anesthesia fluid and gas systems, and the like. In addition, blood
pressure monitoring systems, pulmonary function testers, also can
be easily adapted to employ the present invention to measure mass
flow. Industrial gas cylinders, compressors, pumps, fans, fluid
meters, paint spray systems, I.V. feed systems, and the like are
equally amenable for using the present invention to measure mass
flow.
With reference to the particular embodiment depicted in FIG. 19
an inhalation aerosol delivery device 90 is depicted. Device 90
includes a support 92 which holds an aerosol canister 94 in place.
Canister 94 is typically activated by pressing on base 96 according
to directional arrow 98. For example, canister 94 may contain salmeterol
xinafoate used to treat asthma. With reference to FIGS. 20 and 21
it may be observed that device 90 possesses a fluid exit 100 having
a flow chamber 102. The aerosol emanating from canister 94 exits
nozzle 104 when canister 96 is pressed, as hereinabove described.
Device 10C is adapted to receive aerosol generated by device 90
through the use of a housing 104. Housing 104 possesses a wall portion
106 forming a chamber 108 therewithin. Chamber 108 includes an entrance
member 110 having an entrance chamber 112. Entrance member 110 slips
into flow chamber 102 of fluid exit fitting 100. Thus, chamber 102
of fluid exit fitting 100 communicates with entrance chamber 112
of entrance member 110.
Flow body 114 is located within chamber 108. Flow body 114 includes
a first conical portion 116 a second conical portion 118 and an
intermediate cylindrical portion 120. Flow body 114 is similar to
flow body 42 depicted in FIG. 11. Pylon 122 supports flow body 114
centrally within chamber 108. In addition, the measuring passageways
determining P.sub.1 and P.sub.2 terminate in a open receptors 124
and 126.
An instrument, comparable to the pressure measuring system described
with respect to embodiment 10A, FIGS. 1-5 may be employed in the
form of a plug in schematically represented module 128 having a
display 130 for indicating mass flow passing through chamber 108.
Directional arrow 132 indicates the interconnection direction between
module 128 and receptors 124 and 126.
In operation, the user activates aerosol delivery device 90 by
pressing canister 94 according to directional arrow 98. Aerosol
is then released from nozzle 104 and passes through chamber 102
of exit fitting 100 and into chamber 108 of entrance member 110
of device 10C. Flow body 114 then permits the measurement of mass
flow within chamber 108 of device 10C. In addition, the aerosol
is slowed and enhanced for ingestion by the user. That is to say,
it is believed that the vortex eddy field generated by flow body
114 tends to polarize the aerosol particles to prevent lumping or
agglomeration which would result in deposition within chamber 108.
The aerosol is also warmed to room temperature which allows the
user to comfortably ingest the aerosol generated by device 90.
Referring again to FIGS. 19 and 23 it may be observed that a rotatable
ring 134 includes a multiplicity of slots such as slots 136 and
138. Slots 136 and 138 are alignable with slots through wall portion
106. FIG. 19 illustrates slot 136. The alignment of wall portion
slot 136 and ring 140 in whole or in part permits air to pass into
chamber 108 with the movement of the aerosol exiting fluid exit
fitting 100 of device 90. Directional arrow 142 indicates the movement
of air into chamber 108 in this manner.
While in the foregoing, embodiments of the present invention have
been set forth in considerable detail for the purposes of making
a complete disclosure of the invention, it may be apparent to those
of skill in the art that numerous changes may be made in such detail
without departing from the spirit and principles of the invention.
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