Adjustable weir for liquid distribution systems

An adjustable weir for use in a liquid distribution system utilizes a weir plate having a weir opening whose height can be adjusted vertically. The weir plate is mounted to the end of a fluid distribution outlet in a manner which will maintain its proper orientation while allowing its vertical position with respect to the outlet opening to be varied.

FIELD OF THE INVENTION 
The present invention is directed generally to an adjustable weir for use 
in a liquid distribution system. More particularly, the present invention 
is directed to a height adjustable weir for a liquid distribution system. 
Most specifically, the present invention is directed to a height 
adjustable weir for control of low flows in a sewage distribution system. 
The adjustable weir or weirs are shiftable vertically to place them at 
proper heights so that the flow rates of fluid flowing from a fluid 
distribution center, such as a distribution box to a reservoir out through 
a plurality of distribution or drain lines or conduits can be controlled. 
The individual vertically adjustable weirs can be positioned to provide 
equal flow rates through each distribution line or can be set or 
positioned to provide unequal flow rates, if desired. Each adjustable weir 
has an opening which is, in its operative position, significantly larger 
at the top of the weir than at the bottom of the weir. 
DESCRIPTION OF THE PRIOR ART 
Liquid distribution systems have used weirs as flow control devices for a 
very long time. The use of a weir or dam to control flow from a 
distribution source through one or more of a plurality of distribution 
lines or channels was practiced by ancient farmers and is still in use 
today. A rudimentary weir can be adjusted by the simple expedient of 
piling more dirt in the flow path of an irrigation channel to reduce the 
flow. In more complex fluid distribution systems, adjustable weirs have 
found applications. In large water distribution systems there have been 
provided generally complex, cumbersome flow control gates, valves, and 
similar assemblies which are usable to control the flow of liquid. 
In many areas of the country, home sewage effluent is handled by use of a 
septic tank and a distribution field. The sewage flows by gravity into the 
septic tank, typically in a very non-uniform or surging manner. The 
effluent is collected in the septic tank and may undergo settling or 
treatment. As the liquid level in the septic tank increases, the liquid 
will flow from the septic tank to a fluid distribution point or center 
which is typically a fluid distribution box. This distribution box or 
"tee" then distributes the liquid flow to several subsurface absorption 
areas through fluid distribution pipes or conduits. 
The distribution box is typically provided with generally vertical walls 
having spaced apertures or knock-outs into which the ends of the 
distribution pipes are placed. These pipe ends have, in the past, acted as 
flow dividing weirs. In an ideal situation, the distribution box will be 
installed in a perfectly level manner and the low rate or volume flow 
through each of the various distribution pipes or conduits, to the several 
subsurface absorption areas will be equal. In actuality, the distribution 
box is either initially not perfectly level or, as frequently occurs, 
settles or shifts during installation. The inlets from the distribution 
box to the various distribution pipes or conduits are thus no longer at 
the same level This results in unequal liquid flows to the subsurface 
absorption areas with a possible resultant over-saturation of one 
absorption area and no or very little flow to other areas. Since the flow 
rate through the lowest distribution pipe will have to reach some minimum 
value before the head inside the distribution box rises enough for there 
to be flow through any of the higher pipes, the result is a very poor flow 
division in the flow distribution box. These distribution points or boxes 
are always installed downstream of the septic tank. The sewage flow rates 
from the distribution point to the absorption areas are low and the flow 
distribution is apt to be very uneven and thus not particularly 
satisfactory. 
One prior art solution for this problem has been the provision of flow 
equalizing weirs which are placed on or over the ends of the distribution 
pipes in the distribution box. These flow equalizing weirs are described 
in detail in U.S. Pat. Nos. 5,107,892 and 5,154,353, both to Richard F. 
Plachy, a co-inventor of the subject invention. The specifications of 
these patents are incorporated herein by reference. In the prior Plachy 
patents, equalization of flow is obtained by the use of distribution weirs 
with each such weir having an outlet opening from the distribution box to 
the distribution pipe which is generally U-shaped or cusp-shaped. Such a 
shape will allow the weirs to essentially be self-leveling, as discussed 
in the respective patents. 
Other prior art solutions have been proposed to attempt to solve these 
problems in septic systems. One such solution is to drop the effluent over 
a knife edge as a means of flow division. This is shown in the prior art 
U.S. Pat. Nos. 3,497,067 and 4,605,501 to Tyson. Other attempted solutions 
have been to use dosing systems which pulse or transiently increase the 
flow rate, and by using a round orifice whose height is adjustable, as 
shown in U.S. Pat. No. 4,298,470 to Stallings. None of these prior art 
solutions has proved to be particularly effective. 
The prior art has not provided a solution to the problem of non-uniform 
fluid distribution in a septic system. Each of the various prior art 
devices suffers from one limitation or another and has thus not provided a 
suitable solution. The adjustable weir for liquid distribution systems in 
accordance with the present invention overcomes the limitations of the 
prior art and is a significant improvement in the art. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide an adjustable weir for 
a liquid distribution system. 
Another object of the present invention is to provide a height adjustable 
weir for a liquid distribution system. 
A further object of the present invention is to provide a height adjustable 
weir for control of low flows in a sewage distribution system. 
Yet another object of the present invention is to provide a method for 
using height adjustable weirs to control fluid flow distribution in a 
septic system. 
Still another object of the present invention is to provide an adjustable 
weir which can be properly positioned during installation in a 
distribution box. 
Even yet a further object of the present invention is to provide a 
vertically height adjustable fluid flow distribution weir that is simple, 
durable and reliable. 
As will be discussed in detail in the description of the preferred 
embodiments which is presented subsequently, the adjustable weir for 
liquid distribution systems in accordance with the present invention is 
particularly intended to be usable with a septic system having a fluid 
distribution point, such as a distribution box, to facilitate the flow of 
liquid from the distribution point, through a plurality of distribution 
pipes or conduits and to separate absorption areas in a controllable 
manner. In most instances, the adjustable weirs that are located at the 
fluid distribution point will be placed on the distribution box end of 
each of the plurality of distribution pipes and will all be positioned in 
their operative positions to equalize the flows through the various 
distribution lines. However, if it should be desirable to vary the flows 
through individual distribution conduits to accomplish more flow to, for 
instance, a particular absorption bed, the adjustable weirs can be set 
individually to accomplish this result. 
In accordance with one preferred embodiment of the invention, the generally 
U, V, or cusp-shaped weir is formed in a circular plate which is, in turn, 
mounted eccentrically in a larger, rotatable plate that is positionable in 
the fluid distribution center such as being mounted on the distribution 
box or on the upstream end of the distribution pipe. This allows the 
vertical positioning or height of the weir to be varied while maintaining 
the proper operative orientation of the weir opening. In a second 
preferred embodiment of the vertical weir in accordance with the present 
invention, the weir is formed in a vertically slidable plate that is 
positioned in the distribution center such as by being attached to the 
distribution box or to the upstream end of the distribution pipe. A 
suitable rotatable knob, together with a rack and pinion arrangement, 
allows the height of the weir opening to be adjusted vertically with 
respect to the centerline of the distribution conduit. 
The adjustable weir for liquid distribution systems in accordance with the 
present invention provides for the division of a liquid stream into two or 
more parts that will be equal even if the several distribution pipes are 
not evenly vertically aligned, and even at low flow rates. This will 
assure equal distribution of low volumes or flows of fluids, such as 
effluent from a septic tank, to several spaced subsurface absorption beds. 
Since each weir is adjustable vertically to its desired height or 
elevation, it is also possible, if desired, to provide unequal flow rates 
through the various distribution pipes. 
The vertically adjustable weirs in accordance with the present invention 
utilize generally U, V, or cusp-shaped weirs. The two embodiments of the 
adjusting assembly both allow the height or vertical positioning of the 
weir to be accomplished while maintaining the appropriate operative 
orientation of the weir opening. In each of the preferred embodiments, the 
weir opening can be shifted vertically while retaining its proper 
operative alignment. 
The adjustable weir for liquid distribution systems in accordance with the 
present invention overcomes the limitations of the prior art. It is a 
substantial advance in the art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring initially to FIG. 1, there may be seen, generally at 10, a liquid 
distribution system in which the adjustable weir in accordance with the 
present invention preferably is used. This liquid distribution system 10 
is typically utilized in a residential environment to distribute liquid 
effluent from the septic tank of a home waste disposal system to a 
plurality of subsurface absorption beds. In such a liquid distribution 
system, effluent is supplied from the septic tank or other similar 
reservoir through an inlet pipe 12 to a fluid distribution center, such as 
a distribution box, generally at 14, generally in the direction of the 
arrow A in FIG. 1. The distribution center or box 14 is depicted as being 
generally rectangular and is provided with spaced side walls 16 and 18, 
spaced end walls 20 and 22, a bottom 24 and would also be provided with a 
top or cover that is not shown in the drawings. These distribution boxes 
14 are typically formed from concrete and typically have a plurality of 
openings 26 in their walls through which a plurality of distribution pipes 
or conduits 28 extend away from the distribution box 14. Effluent which 
enters the distribution box 14 through the inlet line 12 will flow out 
from the distribution box 14 through the plurality of distribution pipes 
28 generally in the direction indicated by arrows B in FIG. 1. 
As may be seen in FIG. 1, each distribution pipe 28 may have an adjustable 
weir, generally at 30, at the distribution box end 32 of each distribution 
or drain pipe 28. Alternatively, each outlet opening in the distribution 
center 14 could be provided with an adjustable weir 30 with the flow 
through each such weir 30 then being directed to a suitable distribution 
pipe or conduit 28. Each adjustable weir 30 has a weir opening 34 which is 
generally U, V, or cusp-shaped. Several suitable weir shapes are depicted 
in more detail in FIGS. 5-7 and will be discussed in greater detail 
subsequently. Each adjustable weir 30 is adjustable generally vertically, 
while remaining in its operative position, by utilization of one of the 
two preferred embodiments of the weir height adjusting mechanisms, as will 
be discussed shortly. The vertical position of each such weir 30 can be 
changed or shifted to compensate for manufacturing inaccuracies in the 
locations of the side wall openings 26, to compensate for the distribution 
box 14 being on other than level footing, or for any other reason which 
would act to cause inequalities in the rate of fluid flows from the 
distribution center or box 14 to the various distribution or drain pipes 
28. By use of the adjustable weirs 30, these problems can be corrected and 
equal rates of flow from the distribution center 14 to the several drain 
pipes 28 will be assured. If it is desirable or necessary for the 
different discharge lines 28 to have differing flow rates, this can also 
be accomplished by varying the heights of the several weir openings 34. 
Each weir opening 34 can be set as desired to accomplish the desired flow 
profile from the distribution box 14. 
Referring now to FIG. 2, there may be seen a first preferred embodiment of 
an adjustable distribution weir 30 in accordance with the present 
invention. It will be understood that in FIG. 2, the side wall 18 of the 
distribution box 14 has been omitted for clarity. A generally circular 
movable weir plate 36 has weir opening 34 formed in it. This movable weir 
plate 36 is provided with an outer peripheral edge 38 that is rotatably 
received in an aperture 40 that is formed in a weir mounting plug 42. The 
aperture 40 is circular so that it will receive the circular weir plate 
36, but is located eccentrically in a face portion 44 of the weir mounting 
plug 42 with respect to a central longitudinal axis 43 of the weir 
mounting plug 42 and forms a weir height adjusting assembly. As may be 
seen in FIG. 2, the weir mounting plug 42 has its face portion 44 sized to 
be larger than an outer diameter of an outlet opening 26 in the 
distribution box 14 or an outer diameter of the distribution pipe 28 with 
which it will be used. The weir mounting plug 42 also has a reduced 
diameter plug body 46 that is sized to be slidably received within the 
outlet opening 26 or within the distribution box end 32 of the 
distribution pipe 28. A pair of spaced lugs 48 are provided in the outer 
surface of the weir plate 36 so that the weir plate 36 can be rotated or 
turned respective to the plug face 44 of the weir mounting plug 42. 
In use, the distribution box 14 is placed in the soil or on whatever 
surface it will be supported by, and is rendered as level as possible by 
conventional means. The various distribution or discharges pipes 28, as 
well as the effluent inlet pipe 12 are inserted through the several wall 
openings 26 in the distribution box. A weir mounting plug 42 is placed in 
each wall outlet opening 26 or in the distribution box end 32 of each 
discharge pipe 28 by insertion of the plug body 46 into the wall outlet 
opening 26 or into the pipe end 32. Each weir mounting plug 42 is oriented 
so that the weir plate 36 which it carries will be at its lowest possible 
level. This is accomplished by placing each eccentrically located aperture 
40 in each plug face 44 with its center as low as possible with respect to 
the centerline of its associated discharge opening. The distribution box 
14 is now filled with liquid until the highest weir opening 34 just starts 
to flow liquid. The several other weir openings 34 in the other discharge 
openings 26 or pipes 28 can now be raised to the same level. This is 
accomplished by rotating each weir mounting plug 42 with respect to its 
opening 26 or its pipe 28 and by concurrently rotating each weir plate 36 
in its weir plug 42. The outwardly projecting lugs 48 facilitate rotation 
of the weir plate 36 in the eccentrically located weir plug aperture 40. 
The weir plate 36 is rotated so that it will remain in its operative 
position which is typically such that its vertical axis of symmetry 50 
will remain vertical. Although not specifically shown in the drawings, it 
will be understood that the weir plate 36 and the weir plug aperture 40 
will be formed with, for example, cooperating lips or flanges so that they 
are rotatable with respect to each other while being relatively leakproof. 
Since the flow rates through the weir openings 34 is typically quite low, 
and further since the distribution pipes 28 are only partially submerged 
in the effluent in the distribution box 14, the interface between the 
rotatable weir plate 36 and the aperture 40 located eccentrically in the 
weir plug face 44 does not have to be totally liquid impervious. 
Similarly, the plug body 46 will be sized so that it will be capable of 
being rotated with respect to the outlet opening 26 or the distribution 
box end 32 of the discharge pipe 28. Once the several adjustable weirs 30 
have all been set, the cover can be placed on the distribution box 14 and 
the box can then be carefully buried. If it is subsequently determined 
that the flow rates have become unequal due to shifting of the ground 
beneath the distribution box 14, the box can be unearthed, its cover 
removed, and the flow rates can again be equalized by changing of the 
height of one or more of the weir openings 34 through rotation of the 
mounting plug 42 and re-alignment of the weir plate 36 to maintain the 
weir opening 34 in its desired operative position. 
Referring now to FIGS. 3 and 4, there may be seen, generally at 60, a 
second preferred embodiment of an adjustable weir in accordance with the 
present invention. This second preferred embodiment 60 will accomplish the 
same result as the first adjustable weir 30; i.e. it will allow the 
elevation of each weir opening to be changed so that the effective 
elevations of all of the weir openings will be at the same height thus 
insuring even flow of the effluent liquid from the distribution box 14 
through each of the several distribution openings 26 or the several 
discharge pipes or conduits 28. 
In the second preferred embodiment 60 of an adjustable weir in accordance 
with the present invention, a weir opening 64 is formed in a movable weir 
plate 66 which is supported for movement generally in a vertical 
direction, as indicated by the arrows C in FIG. 3. The movable weir plate 
66 is generally square or rectangular and is slidably supported between a 
front weir support plate 68 and a leading end of a rearwardly extending 
plug body 70. Weir support plate 68 has a central aperture 72 with this 
central aperture 72 in the front weir support plate 68 being depicted in 
FIG. 3. The rearwardly extending plug body 70 is similar to the plug body 
46 portion of the first preferred embodiment of the adjustable weir 30. 
This plug body 70, which is depicted in FIG. 4 and which may be provided 
with axially spaced thin flexible seal rings 76, is receivable within the 
distribution box end 32 of each of the distribution or discharge pipes or 
conduits 28 or may be placed directly in one of the wall outlet apertures 
26 in the distribution box 14. As was the case with the first preferred 
embodiment, the plug body 70 fits snugly within the distribution box end 
32 of each discharge pipe 28 or the hole 26 in the box 14 but can allow 
the adjustable weir 60 to be rotated within the pipe 28 or distribution 
box wall outlet 26, if necessary to insure that the weir opening 64 is 
properly positioned in operative orientation. 
Referring again to FIGS. 3 and 4, the slidable weir plate 66 is sandwiched 
between the front weir support plate 68 and the leading end of the plug 
body 70 and is restrained from horizontal or lateral shifting by suitable 
guide pins, flanges, or other restraints, one of which is depicted 
schematically at 78 in FIG. 3. These guide pins or tabs 78 extend 
rearwardly from the rear wall of the front weir support plate 68 to allow 
the weir plate 66 to be moved vertically up or down but to prevent the 
plate 66 from moving laterally. 
A weir height adjusting assembly, generally at 80 utilizes, as may be seen 
in FIGS. 3 and 4, a rotatable weir height adjusting knob 82, which is 
secured to a first end 84 of a weir height adjusting shaft 86 which is, in 
turn, supported for rotation in an upwardly projecting ear 88 of the front 
weir support plate 68, as may be seen most clearly in FIG. 4. A pinion 
gear 90 is supported at a second, inner end 92 of the weir height 
adjusting shaft. This pinion gear 90 has gear teeth 94 that are in gear 
mesh engagement with a rack 96 which is formed in an aperture 98 formed in 
an upper portion 100 of the weir plate 66. The weir height adjusting knob 
82 may be provided with a knurled or grooved peripheral surface 104 and 
also with a support flange 106, all as seen most clearly in FIG. 4. The 
shaft 86 may also be provided with suitable detents 108 that interact with 
the support plate 68 to allow the shaft 86 to be rotated in a plurality of 
small steps and to remain at a desired height. 
In use, one of the second preferred embodiments of the adjustable weir, 
generally at 60, in accordance with the present invention is installed in 
the distribution box end 32 of each discharge pipe 28 by insertion of the 
plug body 70 into the pipe end. Alternatively, one adjustable weir 60 may 
be positioned in each distribution center outlet opening 26 by insertion 
of the plug body 70 into the opening 26. The weir height adjusting knobs 
82 are turned to lower all of the weir plates 66 to a lowest operative 
level in which an apex 110 of each weir opening 64 is at the level of a 
lower horizontal edge 112 of the central aperture 72 in the front weir 
support plate 68. Fluid is then allowed to enter the distribution box 14 
and rises in the box until there is accomplished fluid flow out through 
all of the discharge pipes 28. When this point is reached; i.e. when fluid 
flow is just starting in the highest discharge pipe 28, fluid flow into 
the distribution box 14 from the effluent inlet pipe 12 is halted. Now all 
of the weir plates 66 of all of the other adjustable weirs 60 are raised 
by appropriate operation of their individual weir height adjustment 
assemblies 80. This will result in the effective heights of all of the 
weir openings 64 being the same, as was also the case in the first 
preferred embodiment. This will insure that fluid flow from the 
distribution box 14 through the various adjustable weirs 60 to their 
respective distribution pipes or discharge pipes 28 will be equal. It will 
also be understood that, as was also possible with the first preferred 
embodiment of the adjustable weir 30, the individual weir openings 64 can 
be set at different heights with respect to each other, if desired. Such a 
setting might be appropriate if the subsurface absorption beds serviced by 
the various discharge pipes 28 have differing sizes or absorption 
capacities and thus should receive differing amounts of liquid effluent 
from the distribution box 14. 
Referring now to FIGS. 5, 6 and 7, there may be seen several possible weir 
opening profiles that are usable with the present invention. These weir 
shapes are discussed in greater detail in the co-inventor's prior U.S. 
Pat. No. 5,154,353. If the weirs are structured as discussed in this prior 
art patent, then raising one of the weirs will decrease its flow rate, as 
compared to the other weirs by an exact ratio (such as 0:75:1) as compared 
to weirs set to the static water line. This ratio will be maintained over 
the entire range of flow rates. The several weir shapes depicted in FIGS. 
5, 6 and 7 all increase generally in width with increasing height at a 
rate which is linear or greater than linear. This may be done 
monotonically, in a series of straight line segments, or in a series of 
steps. As may be seen these weir shapes are generally U, V, or 
cusp-shaped. 
The adjustable weir assemblies in accordance with the present invention are 
particularly usable to accomplish accurate flow division in a septic 
system. The distribution box is typically only crudely leveled and will 
typically be tipped or shifted during installation of the inlet pipe and 
the distribution pipes. The resultant inaccuracies in flow division which 
would result if the adjustable weirs of the present invention were not 
used, would result in poor performance of the septic system. Placing the 
weir openings all at the same elevation, as is possible by use of the 
present invention provides for equal flows, even at low flow rates. 
While preferred embodiments of an adjustable weir for liquid distribution 
systems in accordance with the present invention have been set forth fully 
and completely hereinabove, it will be apparent to one of skill in the art 
that a number of changes in, for example the overall sizes of the 
adjustable weirs, the specific materials used in their construction, the 
number of pipes in the distribution box and the like could be made without 
departing from the true spirit and scope of the present invention which is 
accordingly to be limited only by the following claims.