A substantially rain-proof louver for mounting in an outside wall of an enclosure. The louver has a perimeter frame and plurality of blades extending across the frame, the blades being upwardly inclined from the outer edges to their inner edges. Each of the blades has a gutter element extending along its outer, lower edge. The gutter element is defined by the lowermost portion of the blade, a vertical flange and a downwardly and inwardly inclined anti-splash lip at the upper edge of the vertical flange, the anti-splash lip overlying, at least in part, the lowermost portion of the blade and extending toward the blade.

FIELD OF THE INVENTION 
This invention relates to what variously have been called weather-proof 
louvers or rain-proof airflow louvers which are installed in the walls of 
buildings or other enclosures or at the ends of ducts to provide for 
ingress or egress of air through the louvers and yet to restrain or resist 
the passage of water from rain storms through the louvers and into the 
interiors of the enclosures. 
THE PRIOR ART 
Many louvers of the general type to which the invention relates have been 
developed and are used at the weather ends of both air intake and air 
exhaust ducts, or simply as air admitting openings. Examples of such 
louvers are shown in Great Britain Patent No. 341,556, in Johnson U.S. 
Pat. No. 3,287,870, and in Dowdell et al, U.S. Pat. No. 3,782,050. 
In all of the mentioned patents, each of the louvers consists of a 
plurality of individual, vertically spaced blades or vanes, the blades in 
each case being inclined upwardly and inwardly with their lower horizontal 
edges at the outer sides of the louvers and their inner horizontal edges 
at the inner sides of the louvers, outer and inner, respectively, 
referring to the exterior side of the building wall or enclosure which is 
exposed to the weather and to rainfall and inner meaning the side remote 
from the exterior. 
Similarly, in all three of these prior art disclosures, each of the blades 
has an upwardly turned lip at its upper inner edge to prevent waterflow 
thereover, and each of them has a water accumulating trough or lip at its 
lower outer edge to serve as a gutter for the accumulation of water 
flowing down the respective blade after impingement against the blade 
surface or captured by its upper flange. In all of these louvers of the 
prior art, the flowing air is deflected by the inclined vanes and, in 
theory at least, the heavier drops of water do not remain in the air 
stream but impinge against and are captured by the louver vanes, run down 
the vanes by gravity into the gutters, and are carried away. 
In both U.S. Pat. Nos. 3,287,870 and 3,782,050, already mentioned, the 
gutter-like elements at the lower outer edges of the blades communicate 
with drainage means located at one or both ends of the blades, the 
drainage means functioning as down spouts into which the accumulated water 
in the gutter elements flows, and from which it is carried away by other 
ducting or gutter means. In some instances the water which had accumulated 
in the gutters and which had flowed down the downspout means is simply 
allowed to flow over an opened lower edge of a bottom of the louver 
construction and down the exterior of the wall of the building or 
enclosure. 
While the louvers of all three of the prior art patents mentioned have been 
moderately successful in achieving their objective, i.e., in reducing the 
volume of water which is carried through the louvers into the interior of 
the building or enclosure or into the duct connected to the inner side of 
the louver, test results indicate that when air flows reach certain 
relatively high velocities large volumes of water actually are carried 
through such louvers. 
SUMMARY OF THE INVENTION 
The present invention consists of a substantially rainproof, air-flow 
louver comprising a plurality of inwardly and upwardly inclined individual 
louver blades, each of the blades having a lip at its upper inner edge for 
preventing the flow of water thereover, and each of the blades having a 
gutter element at its lower outer edge for the accumulation of water, the 
gutter elements being connected to downspout means similar, in general, to 
those of the prior art. However, the instant invention has an improved 
configuration in its gutter element which has been found by test to very 
greatly reduce the volume of water carried through the louver, 
particularly by inhibiting or substantially preventing drops of water 
dripping from upper blades which are deflected inwardly by the air flowing 
between the blades, from splashing into pools of water accumulated in the 
gutter elements of lower blades. 
In addition, a louver embodying the invention departs dramatically from the 
underlying concepts of some of the prior art in that it is so designed as 
to deemphasize the creation of laminar air flow between adjacent louver 
blades which has been found to result in retention in the air flow of 
light weight moisture droplets and the resulting passage thereof through 
the louver.

DISCUSSION OF THE PRIOR ART ILLUSTRATED 
Louvers of the type generally referred to herein have frames comprising 
vertical side channels or jambs 20, a head channel 21, and a sill 22. A 
plurality of individual, vertically spaced blades 23 extends across 
between the jambs 20, each of the blades being upwardly and inwardly 
inclined from its outer side 24 toward its inner side 25. Such blades 
usually have return lips 26 extending along their upper inner edges which 
function to prevent the flow of water over the upper inner edges. 
The blades 23 as illustrated in FIG. 2 are shown according to the teaching 
in the Johnson Patent and each of them has a vertical flange 27 extending 
along its lower, outermost edge. The outer sides of the blades 23 are 
shown in much larger scale in FIG. 7 where it also can be seen that the 
side 24 and flange 27 form a gutter element in which water accumulates 
during a rainstorm and as it flows down the faces of the blades 23, the 
water thus accumulated being indicated in FIG. 7 as an elongated pool 28. 
Such a pool would continuously be present during a heavy rainfall in the 
same fashion as the gutters in a city street often have several inches of 
water present even though the sewer drains at the corners are there. 
Similarly, a louver according to the Dowdell Patent, as illustrated in that 
patent and shown in FIGS. 3 and 5 hereof, comprises a plurality of 
inclined blades 23a each of which has a lip 26a extending along its upper 
inner edge and a vertical flange 27a extending along its lower outer edge. 
As best can be seen by reference to FIG. 8, the blades 23a of the Dowdell 
Patent have troughs 30 which are formed or defined by offset bottom sides 
31, the vertical flanges 27a, and overhanging lips 32. 
As is most clearly shown in FIG. 5 of the drawings, the louver construction 
of the mentioned Dowdell Patent also has downspout means 29a, in this case 
consisting of drain apertures cut in the ends of the troughs 30, one above 
the other, so that water flowing along the troughs 30 is delivered 
downwardly through the downspout means 29a adjacent the jambs 20a either 
to the sill 22a or to the outer surface of the enclosure or building wall, 
as the choice may be. 
The constructions illustrated in FIGS. 2-5 inclusive, and FIGS. 7 and 8 all 
are prior art relative to the improved louver and louver blade of the 
instant invention. The mentioned British Patent No. 341,556 of 1931 is 
generally similar to that of the Dowdell Patent as shown in FIG. 8, for 
example, with the exception that the British construction does not show 
the return lips 32 of the Dowdell construction. 
As in the case of the blades 23 (FIG. 7) a pool of water indicated by the 
reference number 28 is present in each of the troughs or gutter elements 
30 during a heavy rainstorm by the accumulation of water flowing down the 
blades 23a and being blown through the vertical spaces between the blades 
23a just as in the case of the blades 23 of FIG. 7 as taught in the 
Johnson Patent. 
The problem existing in the construction of the two prior art patents to 
Johnson and Dowdell can best be understood be reference to FIGS. 7 and 8 
in the following discussion. 
When heavy rainfall impinges against the outside of a building and, thus, 
against the face of a louver of the type herein discussed, some of the 
rain accumulates as a surface layer on the building wall above the head 
channel 21 and runs down its face as well as accumulating on and running 
down the faces of the flanges 27 or 27a on the lower outer sides of the 
louver blades 23 or 23a. In FIGS. 7 and 8 an attempt has been made to 
indicate this film of water flowing down the outer face of a flange 27 in 
the upper one of a pair of blades 23 and dropping toward the pool 28 in 
the lower one of the blades 23. As diagramatically shown, some of the rain 
drops thus falling down will drop almost vertically; some of them will 
flow along with the air flowing through the space between the adjacent 
blades; some of them will impinge against the upper surface of the next 
lower one of the blades 23 and flow back down that surface to re-enter the 
pool 28; some of the drops will fall downwardly into pool 28 where they 
will splash, throwing up fragmented, smaller drops of less mass in the 
form of what might be called a fine mist. With a substantial air flow 
through the space into which this mist is then projected by the splashing, 
the mist is picked up and carried along with the air as the air flows into 
the interior of the enclosure or duct. The foregoing explanation is based 
upon careful observation of tests of a louver according to the Johnson 
Patent as illustrated in FIG. 7 and a similar test of a louver according 
to the Dowdell Patent as illustrated in FIG. 8. 
In both FIGS. 7 and 8 an attempt has been made to show larger drops of 
water by teardrop shapes and the smaller splashed, resulting mist by small 
circular shapes with arrows indicating their directions of flow. 
It will be observed in both FIGS. 7 and 8 that a large area of the 
respective pools 28 and 28a is open vertically for the direct entry and 
impingement of water droplets into the surfaces of the pools. 
It is believed that the mist creating tendency of louver blades as shown in 
FIG. 8 is even greater than that of louver blades as shown in FIG. 7. Not 
only is there the direct impingement of the falling drops of water into 
the pool 28a but some of those drops of water impinge upon the upper 
surface of the lips 32 and splash, creating a mist which flows downwardly 
by gravity and then is swept around and into the space between the 
respective blades where the air flow is likely to carry it along through 
the spaces between the blades 23a and into the interior of the enclosure 
or duct allegedly being protected by the louver. 
As mentioned earlier, the problem of the mist being carried through the 
louver by the air flowing between the blades is particularly present in a 
louver designed according to the Dowdell Patent because of its emphasized 
so-called laminar flow which Dowdell claims is desirable in that it 
reduces turbulence in the spaces between the blades. However, as will be 
further explained, it is believed that this concept is directly contrary 
to best practice and the instant invention deliberately abandons this part 
of the Dowdell teachings and is contradictory thereto. 
While the foregoing visual observations demonstrated the creation of the 
mist of fine water particles and their entrainment in the air flowing 
through, the actual fact of substantial entrainment and penetration was 
made apparent in the published literature of the Assignee Company of the 
Dowdell Patent. This literature reproduced graphs of water infiltration in 
ounces in 15 minutes versus the velocity in feet per minute through the 
face area of a louver having a face area of 48 inches by 48 inches (16 
square feet) at a 4 inches per hour simulated rainfall rate. The test 
depicted in this published literature was performed at the laboratories of 
the Air Moving & Conditioning Assocation, Inc. according to their test 
procedures. These data and curves illustrating these data were published 
by Dowco Corporation, Assignees of the aforesaid Dowdell, et al, U.S. Pat. 
No. 3,782,050 on page 10.26 DOW of their leaflet which is a part of the 
1975 "Sweet's Catalog" (Volume 10) published by Sweet's Division, 
McGraw-Hill Information Systems Company, New York. 
The data establishing the curve identified as "DBE" have been reproduced in 
FIG. 11 of the drawings of the instant case in two ways, as penetration 
through the "face area" and as penetration through the "free area," both 
curves referring to the data from the insert in the Sweet's Catalog being 
labeled "PRIOR ART." The curves shown and thus labeled for a louver 6 
inches thick from front to back or, in other words, measuring 6 inches 
from the left side of FIG. 3 to the right side thereof. It will be 
realized, of course, that in a louver which measures 6 inches from its 
front to its back the linear length of the individual blades, such as the 
blades 23a of FIG. 3, is approximately 71/2 inches. 
DESCRIPTION OF PREFERRED EMBDOIMENTS 
A louver according to the instant invention is generally indicated in FIG. 
6 by the reference number 33 and, like those of the prior art, comprises a 
plurality of individual blades 34 mounted and arranged in the same fashion 
in which such blades are mounted and arranged in the prior art, for 
examples, the Johnson and Dowdell Patents referred to above. 
Each of the blades 34 (FIGS. 6 and 9) or modified blades 34a (FIG. 10) has 
a gutter element 36 or a trough 37 extending along its lower outer edge. 
In the embodiment of the invention illustrated in FIGS. 6 and 9 the gutter 
element 36 is formed by an outer portion of the blades 34, a vertical 
flange 38 and an inwardly and downwardly extending anti-splash lip 39. As 
in the prior art, when rain strikes the louver some of the raindrops 
impinge against the outer sides of the flanges 38, flow down those flanges 
and drop off. Other raindrops are blown inwardly by the air stream and 
either impinge upon the upper surface of the blade 34, itself, or strike 
the inwardly turned anti-splash lip 39 or (a few) may fall directly into a 
pool 40 which accumulates in the gutter element 36 just as the pool 28 
accumulates in the construction illustrated in FIG. 7. 
However, in sharp and important contrast to the functioning of the 
structure illustrated in FIG. 7 according to the Johnson Patent, the 
tendancy for any of the water to flow through the louver and to pass to 
the interior of the enclosure or duct is greatly reduced by the 
configuration of the louver blades according to the invention. As is 
somewhat diagramatically illustrated in FIG. 9, the area of the pool 40 
which is exposed to falling drops is greatly reduced when compared to the 
area of the pool 28 as illustrated in FIG. 7. Secondly, such drops as 
might otherwise fall into the outermost portion of the pool 40 instead 
impinge against the downwardly and inwardly inclined anti-splash lip 39 
whence they are deflected downwardly again at reduced velocity and are 
less likely to cause splashing and thus the generation of mist which would 
flow through the louver. 
The embodiment of the invention illustrated in FIG. 10 exhibits the same 
improvements over the louver blade construction illustrated in FIG. 8 as 
disclosed in the Dowdell, et al Patent discussed above and has an 
additional improved feature relative to the construction of FIG. 8. In 
FIG. 10 the louver blade 34a has a trough 37 defined by an offset portion 
41 comparable to the offset portion or trough bottom 31 of FIG. 8, and a 
vertical flange 42 comparable to the vertical flange 27a of FIG. 8. 
However, in lieu of the upwardly inclined lip 32 of the construction of 
FIG. 8, that of FIG. 10 has an inwardly and downwardly directed 
anti-splash lip 43 according to the invention. 
Therefore, as can best be appreciated by comparison between FIGS. 8 and 10, 
the incidence of splashing and the generation of fine mist which is 
entrained with the inflowing air is greatly reduced. Raindrops which 
impinge upon the anti-splash lip 43 are not deflected outwardly and around 
the flange 42 to re-enter the air stream as they are in the construction 
illustrated in FIG. 8. Some raindrops are deflected from the surface of 
the blade itself and engage the anti-splash lip 43 and then are deflected 
at lesser velocity into the pool 44 where the splashes they create are 
much smaller. 
Again, the foregoing comments are based upon visual observation of the 
operation of louvers under standard test conditions when equipped with 
blades according to the invention and constitute an effort to explain the 
reason for the dramatic contrasts now to be discussed. 
In performing the tests of louvers embodying the instant invention in order 
to assemble data comparable to the data reported in the mentioned 
publication with respect to louvers embodying the Dowdell Patent mentioned 
above, particularly the DOWCO DBE 6-inch louver, a louver having a 48 inch 
by 48 inch (16 square foot) face area was constructed employing louver 
blades such as those illustrated in FIGS. 6 and 9. The blades were set at 
approximately the same angle as the DOWCO blades -- 35.degree. - 
40.degree. from horizontal. The simulated rainfall of 4 inches per hour 
was the same. The various velocities through the face area in feet per 
minutes were the same. All other test conditions were duplicated under the 
auspices of the testing laboratory at the Air Moving & Conditioning 
Association, Inc. Every effort was made to test louvers according to the 
invention as nearly similar to the louvers referred to in the mentioned 
publication as possible. 
As readily can be seen, in the two sets of comparable curves set forth in 
FIG. 11, water infiltration in response to higher air flow in the case of 
the prior art louver embodying the mentioned Dowdell, et al Patent, 
increased dramatically whether plotted against the face area of the louver 
or the free area. The two curves labeled "PRIOR ART" show that as the 
velocity of the air in feet per minute increased from slightly more than 
400 to slightly less than 600, water infiltration plotted against the face 
area increased from slightly less than one ounce in 15 minutes to almost 
10 ounces in 15 minutes. 
In astonishing contrast, the water infiltration through a louver embodying 
the instant application plotted against the face area was virtually 
imperceptible until a velocity in excess of 500 feet per minute was 
reached and increased only to a fraction of an ounce when the velocity 
reached 650 feet per minute. 
Similarly, when the water infiltration versus the free area was plotted 
according to the published data referred to above, water infiltration at 
800 feet per minute was about 1 ounce and increased dramatically to 
somewhere in the order of 10 ounces when the velocity reached the level of 
1100 feet per minute. Again, in sharp and astonishing contrast in the 
louver according to the instant invention, water infiltration was 
virtually imperceptible until the velocity of the air reached 1000 feet 
per minute and increased to only a fraction of 1 ounce in 15 minutes when 
the velocity reached a level of over 1200 feet per minute. 
The unexpected and astonishing improvement can only result from the change 
in construction made apparent by comparing the cross section of FIG. 9 
with that of FIG. 8. The difference between the curves adjacent each other 
in that portion of FIG. 11 labeled "face area" and the curves adjacent 
each other in that portion of FIG. 11 labeled "free area" cannot be 
explained in any other fashion since all other test parameters, i.e., 
area, velocity, blade angle, louver depth, simulated rate of rainfall, 
test time, etc. were substantially identical.