Abstrict This invention provides a fluid flow meter including an elongated
tube and an element adapted for connection to a fluid line, the
elongated tube including one or more orifice openings of predetermined
area, and indicia correlated with the area of the orifice opening
for providing a reading of fluid flow dependent upon the level to
which fluid rises in the elongated tube. In one embodiment the tube
includes a plurality of scales for indicating different ranges of
flow rates, and an orifice opening corresponding to each of said
scales, said orifice openings being of different areas and selectively
openable so that said scales can individually be made to show fluid
flow rates.
Claims We claim:
1. A flow meter for measuring the volume of fluid flow comprising
fluid passageway means connectable to a fluid transmitting member,
a plurality of scales of indicia on said fluid passageway means
for indicating different ranges of fluid flow rates,
said fluid passageway means defining an orifice opening for each
of said scales, each of said orifice openings having a predetermined
area correlated with said indicia of the one of said scales therefor
for causing said indicia to indicate the quantity of fluid flow
in said fluid transmitting member in accordance with the level of
fluid in said fluid passageway means,
means for selectively opening each of said orifice openings for
allowing fluid in said fluid passage means to discharge therefrom
while closing the remaining ones of said orifice openings for causing
the indicia of the corresponding one of said scales to so indicate
fluid flow,
said fluid passageway means including:
a tube having a light transmissive wall to permit the level of
fluid therein to be seen through said wall,
said orifice openings being adjacent one end of said tube, and
a sleeve having a portion telescoped with respect to said tube and
rotatable relative thereto,
said sleeve having an opening through the wall thereof at least
as large as the largest of said orifice openings, whereby at selected
rotational positions of said tube relative to said sleeve a selected
one of said orifice openings is in registry with said opening in
said sleeve so that fluid received in said sleeve can discharge
through said opening in said sleeve and one of said orifice openings
and can rise in said tube for indicating fluid flow rate.
2. A device as recited in claim 1 including additional indicia
to indicate which of said orifice openings is so opened and which
one of said scales is so caused to indicate fluid flow.
3. A device as recited in claim 1 in which said scales are rotationally
spaced around said fluid passageway means, and in which each of
said orifice openings is opposite from the one of said scales therefor.
4. A device as recited in claim 1 in which said sleeve includes
a first portion for a first outside diameter received within one
end portion of said tube and rotatably retained therein by a friction
fit, a second portion of a second and larger outside diameter exteriorly
of said tube, and a shoulder between said first and second portions,
said tube having a radial end surface engaging said shoulder, said
opening in said sleeve being through the wall of said first portion.
5. A device as recited in claim 4 including an indicia on said
first portion of said sleeve, and a plurality of indicia on said
one end portion of said tube selectively alignable with said indicia
on said first portion at different relative rotational positions
of said sleeve and said tube for indicating which one of said scales
will indicate the flow rate of fluid entering said sleeve and said
tube.
6. A device as recited in claim 5 in which said opening in said
sleeve is positioned on the opposite side of said sleeve from said
indicia on said first portion, and said plurality of indicia on
said one end of said tube include one indicia on the side of said
tube opposite from each of said orifice openings.
7. A device as recited in claim 6 in which each of said indicia
on said one end portion of said sleeve is aligned with one of said
scales.
8. A flow meter for measuring the volume of fluid flow comprising
a tube having a light transmissive wall to permit the level of
fluid therein to be seen through said wall,
said tube having a plurality of orifice openings therethrough,
a plurality of scales of indicia for indicating different ranges
of fluid flow rates with respect to the level of fluid in said tube,
and a sleeve connectable to a source of fluid, said sleeve having
a portion telescoped with respect to said tube and rotatable relative
thereto,
said sleeve having opening means therethrough registrable with
selected orifice openings in predetermined relative rotational positions
of said sleeve and said tube for causing different orifice openings
to discharge fluid from said tube and said indicia of different
ones of said scales to indicate fluid flow in accordance with the
level of fluid in said tube.
Description BACKGROUND OF THE INVENTION
For agricultural and other uses there exists a need for a low-cost,
accurate, reliable, and easily used flow meter. One area of such
need is in drip irrigation systems where there may be a number of
trees to which fluid lines extend, with the flow in each line being
controlled by a valve. It is necessary to regulate the flow to each
tree so that it is given neither too much nor too little water.
A common and unsatisfactory expedient has been to utilize a measuring
cup to receive the water and a stopwatch to measure the time in
which a given amount of water enters the cup. Obviously, this is
time consuming and inconvenient. The alternative has been the use
of an expensive float-type meter which requires careful handling
and maintenance.
SUMMARY OF THE INVENTION
The present invention provides an improved flow meter which is
of low cost, is maintenance free, durable, and is easy to use. The
device is a simple unit with no moving parts during operation. One
end of the unit may include an outwardly tapered tube adapted to
fit within and form a temporary seal at a fluid discharge line.
This tapered tube connects through a 90.degree. elbow to an elongated
straight tube which is positioned vertically when the fluid flow
is being measured. At the lower end of the tube is an orifice opening,
above which is a scale for indicating the quantity of fluid flow.
The tube is frictionally held on the elbow and rotatable relative
to it, which permits positioning of the scale in the best location
for viewing it.
When the device is connected to a fluid line, the fluid will flow
through the tapered tube and the elbow into the straight tube. There
some of the fluid will discharge through the orifice opening and
the remainder will rise in the tube to a level which is dependent
upon the rate of flow in the line. The area of the orifice opening
is correlated with the scale on the straight tube to enable a direct
reading of flow rate to be made. Consequently, it is a simple matter
to associate the flow meter with a fluid discharge line and regulate
the rate of flow in the line to a desired value.
Because of the relationship of the column of liquid in the tube
with respect to flow rate, there is a rapid expansion of the length
of the scale upwardly as flow rates increase. This means that for
high flow rates the length of the tube would have to be too long
to be practical and simple to use. This difficulty is avoided by
the inclusion of a second orifice opening outwardly in the tube,
beyond which is a second scale correlated to the area of both the
first and second orifice openings. Thus, when the liquid reaches
the second orifice opening, there is more area for discharge of
the liquid and the scale for indicating flow rate is condensed considerably.
If desired under some circumstances, there may be three or more
discharge orifices spaced outwardly along the tube.
In another embodiment, the tube includes a plurality of scales
on its wall for indicating different ranges of flow rates. An orifice
opening of appropriate area is provided for each of the scales.
A sleeve telescopes relative to the tube and has an opening at least
as large as the largest of the orifice openings in the tube. Therefore,
the tube and sleeve may be relatively rotationally positioned to
open a selected one of the orifice openings while closing the others,
thereby rendering the corresponding scale operative. In this manner,
the flow meter is easily adjusted to give a direct and accurate
reading in several flow ranges. Indicia on the sleeve and tube show
which of the scales and orifices have been selected.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevational view of the flow meter of this invention;
FIG. 2 is an enlarged fragmentary sectional view of the lower portion
of the flow meter;
FIG. 3 is a side elevational view of the flow meter associated
with a fluid line;
FIG. 4 is a side elevational view of a modified form of the invention
used for higher flow rates;
FIG. 5 is a front elevational view of another embodiment of the
invention which is adjustable for indicating different flow ranges;
FIG. 6 is a rear elevational view of the flow meter of FIG. 5;
FIG. 7 is an enlarged transverse sectional view taken along line
7--7 of FIG. 5;
FIG. 8 is an enlarged fragmentary longitudinal sectional view taken
along line 8--8 of FIG. 5;
FIG. 9 is a fragmentary front elevational view of the flow meter
in a different position of adjustment;
FIG. 10 is a fragmentary rear elevational view of the flow meter
adjusted as in FIG. 9;
FIG. 11 is a fragmentary front elevational view of the flow meter
in a third position of adjustment; and
FIG. 12 is a fragmentary rear elevational view of the flow meter
adjusted as in FIG. 11.
DETAILED DESCRIPTION OF THE INVENTION
The flow meter 10 illustrated in the drawing is particularly adapted
for use in drip irrigation systems. It includes an elongated tube
11 of transparent plastic material open at both its ends. A scale
12 is marked on the tube 11 together with numbers which indicate
the rate of flow, as explained below. The scale is not linear, having
progressively greater distances between the markings of the scale
in the vertical direction toward the higher numbers, as the device
is illustrated. Spaced upwardly a short distance from the lower
end 13 of the tube 11 is an orifice 14.
A 90.degree. elbow 16 also of plastic material, is at the lower
end 13 of the tube 11 with an end portion 17 of the elbow being
inserted into the tube (see FIG. 2). The tip end of the elbow is
frustoconical in shape, facilitating its entry into the tube 11
and it frictionally grips the wall of the tube at the base of the
frustoconical portion. This holds the elbow and tube together, as
well as forming a seal at this location. This also allows the tube
11 to be rotated relative to the elbow so that the scale 12 can
be positioned where it is most readily viewed. This is especially
important in irrigation systems where there may be plant growth
limiting access to the location where the flow is being calibrated.
Inwardly of the frustoconical end portion 17 the elbow has a portion
18 of reduced diameter connecting through a radial shoulder 19 to
the central portion 20 of the elbow. The shoulder 19 bears against
the end 13 of the tube 11 which positions the tube 11 axially relative
to the elbow 16.
The other end 22 of the elbow 16 is similar and fits within a tapered
plastic tube 23. The latter element, which converges outwardly away
from the elbow 16 extends over a part of the central section 20
of the elbow, engaging the elbow with a friction fit that also provides
a seal.
The flow meter 10 is used by inserting the tapered tube 23 into
a component of the fluid line which is to be measured. In the example
illustrated, the tube 23 is fitted into the outlet end 25 of a valve
26 which is at the end of a fluid line 27 forming a portion of a
drip irrigation system. The outlet 25 of the valve 26 defines a
cylindrical bore 28 into which the tapered tube 23 is wedged, forming
a temporary attachment and a seal. The flow meter is positioned
so that the tube 11 is vertical.
Water flowing through the valve 26 passes through the elbow 16
and enters the tube 11. A portion of the liquid is discharged outwardly
through the orifice opening 14. Another quantity of the liquid rises
in the tube 11 to a level which is indicative of the volume of flow
in the line 27. In the example illustrated, if the liquid rises
to the height of the marking at the numeral 3 on the tube 11 this
will show a flow of three gallons per hour in the line 27. The flow
rate may be set by further opening or closing of the valve 26 to
achieve a desired volume as indicated by the level of the column
of liquid in the tube 11.
The theory of operation of the flow meter 10 is found in the formula
Q=CA.sqroot.2gh, where Q=flow in cubic feet per second, C=contraction
coefficient of the orifice opening 14 which is dependent upon the
edge shape of this opening, A=the area of the orifice opening, g=the
acceleration constant of gravity, feet per second per second, and
h=the height in feet of the liquid in the tube 11. From this relationship
the diameter of the orifice opening 14 can be selected and the indicia
markings 12 inscribed on the tube 11 at the appropriate locations
to make a direct reading of flow in gallons per hour or such other
units as the circumstance requires.
The orifice opening may be positioned in the elbow 16 instead of
the tube 11. However, the flow meter is more easily manufactured
by forming this opening in the tube 11 as illustrated. This requires
some adjustment of the scale 12 to reflect a higher position of
the orifice than that of the base of the column of liquid.
Because flow varies in proportion to the square root of the height
of the column of liquid in the tube 11 the scale 12 becomes increasingly
spread out as flow volume increases. In other words, the distance
between adjacent scale markings 12 increases as the higher flow
values are realized. This means that for a flow meter capable of
measuring higher rates of flow a very long tube 11 would be required.
It becomes impractical to construct a flow meter of the type of
FIG. 1 capable of measuring higher flow rates because the very long
tube 11 is unwieldy and difficult to use. The problem is alleviated
by the modification illustrated in FIG. 4. Here the tube 30 corresponds
to the tube 11 and is associated with an elbow end tapered as in
the previously described embodiment. The length of the tube 30 may
be the same as that of the tube 11. Adjacent the lower end 31 of
the tube 30 is an orifice opening 32 to bleed out a portion of the
liquid which enters the flow meter. Above the opening 32 is a scale
33 similar to the scale 12 in the previously described embodiment.
However, the diameter of the orifice opening 32 is selected so as
to compress the scale 33 as compared with the scale 12. This means
that the opening 32 is given a greater area than that of the opening
14 so that a flow volume of five gallons per hour, at the upper
end of the scale 33 is indicated approximately at the midpoint
of the tube 30.
Above the scale 33 is a second orifice opening 34 beyond which
is a second scale 35. The latter scale extends to the upper end
portion of the tube 30 indicating a flow rate of 10 gallons per
hour at the upper extremity.
In operation, the flow meter indicates flow up to five gallons
per hour in the manner described for the flow meter 10. At a flow
rate of between five and six gallons per hour, the liquid level
in the tube 11 reaches the second orifice opening 34. At this point
a greater quantity of liquid can bleed out of the flow meter because
fluid is discharged through both the orifice opening 32 and the
orifice opening 34. With this greater flow through the flow meter
automatically increasing the area of discharge, the second scale
35 becomes greatly compressed and can be accommodated on the tube
30. By this technique the flow meter may be of a small and easily
handled size and will switch from one scale to the other as flow
rates increase to indicate a larger range of flow volumes.
In the embodiment of FIGS. 5 through 12 the flow meter is adjustable
to give readings within different ranges of flow. This embodiment
includes an open-ended transparent tube 37 normally of plastic,
on which are three scales 38 39 and 40 for indicating three different
flow ranges. For example, the scale 38 may be for flow rates of
from one to five gallons per hour, scale 39 for flow rates of six
to twenty-four gallons per hour, and scale 40 for flow rates of
twenty-five to fifty gallons per hour. The tube 37 near its base
and beyond the scales 38 39 and 40 includes three outlet orifices
41 42 and 43. These outlet orifices have their centers in the same
radial plane through the tube and are of different sizes. The orifices
are for discharging liquid selectively to enable the different scales
38 39 and 40 to indicate the flow rate, depending upon the range
of flow. Each of these openings is on the side of the tube diametrically
opposite from the one of the scales 38 39 and 40 to which it corresponds.
Thus, the orifice 41 of smallest size, is opposite from the scale
38 the intermediate sized orifice 42 is opposite from the scale
39 and the largest orifice 43 is opposite from the scale 40.
A plastic sleeve 45 includes a lower end portion 46 of relatively
large outside diameter and an upper end portion 47 of smaller outside
diameter. A radial shoulder 48 interconnects these two sections.
The upper end portion 47 fits within the lower end of the tube 37
with the radial lower end edge 49 of the tube engaging the shoulder
48. A friction fit holds the tube 37 on the end portion 47 of the
sleeve 45 while permitting relative rotation of these two members.
Internally, the sleeve 45 includes a bore section 50 that extends
from its upper end 51 to a location beyond the external shoulder
48. The intermediate bore portion 52 is larger than the bore 50
and a counterbore 53 extends inwardly from the lower end 54 of the
sleeve 45.
Extending through the wall of the upper portion 47 of the sleeve
45 between the upper end 51 and the shoulder 48 is an opening
55 which is of larger diameter than the largest orifice 43 through
the wall of the tube 37. The opening 55 is positioned the same distance
from the shoulder 48 as the orifices are from the lower end 49 of
the tube 37 so that the opening 55 can be in registry with any
one of the orifice openings 41 42 and 43 depending upon the relative
rotational positions of the tube and the sleeve 45.
In use of the flow meter of FIGS. 5 through 12 the tube 37 and
sleeve 45 are rotationally positioned to bring the desired scale
of flow rates into position for operation. If, for example, flow
in the range of one to five gallons per hour is to be measured,
the opening 41 is placed in registry with the opening 55 through
the sleeve 45 as shown in FIGS. 5 through 8. The opening 41 is
of an area such that it can discharge liquid entering the sleeve
45 at a rate to cause the level to which the liquid rises in the
tube 37 to indicate total flow rate on the scale 39.
There are markings on the tube 37 and sleeve 45 to facilitate alignment
of the appropriate orifice in the tube 37 with the opening 55 in
the sleeve. This includes a mark 57 on the lower portion 46 of the
sleeve 45 adjacent the shoulder 48 and on the side opposite from
the opening 55. On the sleeve 37 are arrows 58 59 and 60 beneath
the scales 38 39 and 40 respectively. Alignment of one of these
arrows with the mark 57 means that the orifice of the scale directly
above is in registry with the opening 55 in the sleeve 45 so that
that scale is made functional. In the example of FIGS. 5 through
8 therefore, the arrow 58 is in alignment with the mark 57 indicating
that the scale 38 above the arrow 58 will show the flow rate because
the orifice 41 then coincides with the opening 55 and is in a position
to discharge fluid.
As shown in FIGS. 5 6 and 8 the outlet of a valve 61 which is
attached to a fluid transmitting line 62 is inserted into the lower
end of the sleeve 45. The outlet of the valve illustrated includes
an elongated frustoconical portion 63 which tapers at a shallow
angle toward the valve body and connects through a shoulder 64 to
a frustoconical end portion 65 that tapers toward the outer end.
The corner of the outer tapered portion 65 adjacent the shoulder
64 engages the wall of the counterbore 53 of the sleeve 45 and
the wall of the portion 65 engages the corner at the end of the
bore section 52 so that a fluid-tight connection is made to the
flow meter. Then the liquid discharging from the valve 61 which
in this instance is water used in an irrigation system, flows into
the fluid passageway that the flow meter defines, first entering
the sleeve 45. Some of this water rises in the tube 37 while the
orifice 41 discharges the remainder of the water. In the manner
described above, the scale 38 then gives a reading of the flow rate.
FIGS. 9 and 10 are opposite views of the flow meter adjusted so
that the intermediate orifice 42 is registered with the opening
55 and the scale 39 is functional to measure flow in the range of
six to twenty-four gallons per hour. Similarly, FIGS. 11 and 12
show the opposite sides of the flow meter in the third position
where the largest orifice 43 coincides with the opening 55 and the
scale 40 will indicate the fluid flow rate in the rage of twenty-five
to fifty gallons per hour.
It is a simple matter to relatively rotate the tube 37 and the
sleeve 45 to render any of the scales operative with its orifice
registering with the discharge opening 55 in the sleeve 45. In fact,
if it is attempted to use one of the scales and it proves to be
the wrong one, the flow meter readily is adjusted while in position
on the discharging device to cause another one of the scales to
come into use so that the meter will give the proper range of flow.
Although there is no difficulty in aligning the arrows 58 59 and
60 with the mark 57 precise positioning is not necessary. This
is because the opening 55 is larger than even the largest orifice
43 and allows the orifice to discharge without obstruction even
though the center of orifice does not exactly coincide with the
center of the opening 55.
The foregoing detailed description is to be clearly understood
as given by way of illustration and example only, the spirit and
scope of this invention being limited solely by the appended claims. |