U.S. patent number 3,771,276 [Application Number 05/271,889] was granted by the patent office on 1973-11-13 for multiple-glazed breather windows.
This patent grant is currently assigned to PPG Industries, Inc.. Invention is credited to George H. Bowser, John L. Stewart.
United States Patent |
3,771,276 |
Stewart , et al. |
November 13, 1973 |
**Please see images for:
( Certificate of Correction ) ** |
MULTIPLE-GLAZED BREATHER WINDOWS
Abstract
A multiple-glazed unit provided with breather apparatus
comprising a capillary tube connected to an elongated column of
desiccant material.
Inventors: |
Stewart; John L. (Apollo,
PA), Bowser; George H. (New Kensington, PA) |
Assignee: |
PPG Industries, Inc.
(Pittsburgh, PA)
|
Family
ID: |
23037518 |
Appl.
No.: |
05/271,889 |
Filed: |
July 14, 1972 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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70840 |
Sep 9, 1970 |
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Current U.S.
Class: |
52/172; 55/385.1;
96/133 |
Current CPC
Class: |
E06B
3/6707 (20130101); E06B 3/677 (20130101) |
Current International
Class: |
E06B
3/677 (20060101); E06B 3/67 (20060101); E06B
3/66 (20060101); E06b 007/12 () |
Field of
Search: |
;52/172,616 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Murtagh; John E.
Parent Case Text
This application is a continuation of application Ser. No. 70,840,
filed Sept. 9, 1970, now abandoned.
Claims
We claim:
1. In a glazing unit comprised of a pair of rigid sheets supported
in opposed, spaced relation to each other by perimeter, marginal
edge spacer means defining with said sheets an enclosed space
therebetween, said perimeter spacer means having a dehydrator
carried thereby in communication with said enclosed space, the
improvement which comprises a breather device comprising:
an elongated tube filled with a column of desiccant supported by
said perimeter spacer means, said elongated tube having a first
opening in the wall of said tube adjacent one end thereof and
located in the enclosed space of said unit adjacent said
dehydrator, and a second opening in the wall of said tube spaced
from said first opening and adjacent the other end of said
elongated tube, and
an elongated, open-ended capillary tube having one end thereof
connected to said elongated tube at said second-named opening
therein and the other end thereof exposed and open to the
atmosphere surrounding said glazed unit to provide an open passage
for air between the enclosed space of said glazed unit and the
atmosphere surrounding said unit,
whereby the atmosphere surrounding said glazed unit is free to pass
through said elongated, open-ended capillary tube and through
substantially the entire column of desiccant within said elongated
tube into the enclosed space of said glazed unit.
2. The glazing unit of claim 1 in which the dehydrator comprises a
desiccant material dispersed in a matrix of moisture vapor
transmittable material.
3. The glazing unit of claim 1 in which the dehydrator comprises
bags of desiccant material.
4. The glazing unit of claim 2 which further includes sections of
channeling disposed about the perimeter of the unit and wherein
said capillary tube has a free end residing in a space defined
between said channeling and adjacent edge portions of said
unit.
5. The glazing unit of claim 3 which further includes sections of
channeling disposed about the permimeter of the unit and wherein
said capillary tube has a free end residing in a space defined
between said channeling and adjacent edge portions of said
unit.
6. The glazing unit of claim 3 wherein said spacer means comprises
a channel member containing an air permeable material and said
channel member is closed on a side facing said enclosed space with
a foraminous strip.
7. The glazing unit of claim 1 wherein at least one of said rigid
sheets is comprised of tinted glass.
8. The glazing unit of claim 1 wherein at least one of said rigid
sheets is comprised of glass coated with a transparent, reflective
film.
9. In a glazing unit comprised of a pair of rigid sheets supported
in opposed, spaced relation to each other by perimeter, marginal
edge spacer means defining with said sheets an enclosed space
therebetween, said perimeter spacer means having a dehydrator
carried thereby in communication with said enclosed space, the
improvement which comprises a breather device comprising:
an elongated tube filled with a column of desiccant, said elongated
tube being separate from and located adjacent said perimeter spacer
means and having a first opening adjacent one end thereof located
in communication with the enclosed space of said unit adjacent said
spacer means, and a second opening spaced from said first opening
and located adjacent the other end of said elongated tube in
communication with and open to the atmosphere surrounding said unit
to provide an open passage for air between the enclosed space of
said unit and the atmosphere surrounding said unit,
whereby air from within the enclosed space of said unit and from
the atmosphere surrounding said unit is free to pass through
substantially the entire column of desiccant within said elongated
tube.
10. The glazing unit of claim 9 which further includes an elongated
open-ended capillary tube having one end thereof connected to said
elongated tube at said second-named opening therein and the other
end thereof exposed and open to the atmosphere surrounding said
unit to further provide said open passage for air between the
enclosed space of said unit and the atmosphere surrounding said
unit,
whereby air from within the enclosed space of said unit and from
the atmosphere surrounding said unit is free to pass through said
elongated open-ended capillary tube and through substantially the
entire column of desiccant within said elongated tube.
Description
BACKGROUND OF THE INVENTION
This invention relates to a novel multiple-glazed unit and, more
specifically, to a multiple-glazed unit provided with a breather
device. In particular, the invention relates to multiple glazed
units provided with a breather device or apparatus comprising a
length of capillary tubing connected to an elongated column of
desiccant material. In accordance with the invention, a free end of
the capillary tube is in open communication with the air
surrounding the unit while the desiccant column, to which the
capillary tube is connected at its opposite end, is in
communication with the enclosed, insulating space of the
multiple-glazed unit.
In the past, various types of breather devices have been used on
multiple-glazed units. One such breather device is fully disclosed
in U.S. Pat. No. 3,838,809, assigned to the assignee of the present
invention. In accordance with the aforementioned patent, a
multiple-glazed unit is constructed comprising a plurality of glass
sheets separated at their marginal edges by a hollow spacer element
containing a desiccant material, an elongated strip of mastic in
sealing contact with the edges of the glass sheets and the spacer
element and a pressure sensitive tape covering the strip of mastic.
The unit is provided with an aperture or aligned opening through
the tape, mastic and outer wall of the spacer element, to connect
the atmosphere with the desiccant, and at least one other opening
through the inner wall of the spacer element communicating with the
insulating space of the unit. The openings or apertures permit the
unit to "breathe" through the desiccant material due to changes of
atmospheric conditions.
Although the aforementioned type of unit construction is useful, it
has been found that it possesses a number of inherent deficiencies.
For example, it has been found that the breather opening through
the tape, mastic, and outer wall of the spacer element can be
blocked, obstructed or pressed closed either by inadvertent or
careless handling or by foreign material collecting therein.
Moreover, the desiccant material may be caused to adsorb a
considerable amount of moisture during breathing, such that the
available quantity of desiccant to keep the unit dry is
substantially diminished. Also, if the aperture through the tape,
mastic, and outer wall of the spacer element is too large, liquid
moisture from condensation, rain or leakage around the perimeter of
the unit can enter this aperture causing a rapid reduction in the
unit's dew point over what might be expected due solely to moisture
vapor diffusion from changes in atmospheric conditions of
temperature, barometric pressure, and humidity.
Accordingly, it is an object of this invention to provide an
improved breather device for multiple glazed units such that the
above-mentioned problems are eliminated or substantially reduced.
In accordance with the invention, this object is accomplished by
providing multiple glazed units with a breather device comprised of
a capillary tube connected to a column of desiccant, so that a free
end of the capillary tube is in open communication with the air
surrounding the unit while the desiccant column, to which the
capillary tube is connected at its opposite end, is in
communication with the enclosed, insulating space of the unit.
The foregoing and other objects, features and advantages of the
present invention will become more apparent from that which
follows, when taken in conjunction with the drawings, in which:
FIG. 1 is a perspective view of a multiple-glazed unit constructed
in accordance with this invention;
FIG. 2 is a cross-section along the line II--II of FIG. 1 showing
details of a preferred edge construction incorporating the breather
device of this invention;
FIG. 3 is a fragmentary perspective view, partly in section and
partly broken away, of a side edge of the unit of FIG. 1 showing
further details of a preferred embodiment of this invention;
and
FIG. 4 is a cross-section similar to that of FIG. 2 showing details
of another embodiment of this invention.
Illustrated in FIGS. 1 to 4 are acoustical multiple-glazed unit
constructions that advantageously employ the breather device of
this invention in their structures. Shown in FIGS. 1 to 3 are
details of one preferred acoustical multiple-glazed unit 10 in
which glass sheets 12 and 14 are of unequal thickness to achieve a
mismatch of their resonent frequencies, hence better reduction of
sound transmission through the unit. Also, glass sheets 12 and 14
are spaced apart to provide an insulating space therebetween of
about 1 inch or greater, preferably from about 2 inches to about 4
inches, to enhance sound transmission loss through the unit. The
marginal edge portions of the glass sheets are rigidly supported at
the desired spaced apart distance by a perimeter spacer channel 16
adhered by a layer or bead of moisture-resistant, air-impermeable
mastic 18 to the marginal edge portions of both glass sheets.
Spacer channel 16 is preferably composed of aluminum or galvanized
steel and, in the embodiment shown, has an essentially U-shaped
cross-section. As shown, the web 20 of spacer channel 16 is
disposed adjacent the perimeter of the unit and the flanges or legs
22 of the U-channel extend inwardly of the unit therefrom. Flanges
22 are preferably L-shaped and their free ends are disposed in
opposed, spaced relation to each other.
Inserted within spacer channel 16 and extending essentially
coextensive in length with each side of the unit are four abutting
lengths of dehydrator element 24. The composition of dehydrator
element 24 is now fully disclosed in applicants' assignee's U.S.
application Ser. No. 42,712, the disclosure of which is intended to
be incorporated herein by reference. Broadly, dehydrator element 24
comprises a desiccant material dispersed in a matrix of moisture
vapor transmittable material, such as a thermoplastic, block
copolymer of styrene-butadiene rubber as is now disclosed in U.S.
Pat. No. 3,265,765.
Dehydrator element 24, as shown, preferably has a modified U-shaped
cross-section, such that when inserted in spacer channel 16 an
elongated space 26 is defined between dehydrator element 24 and the
web 20 of spacer channel 16. Residing in this space 26 is an
elongated column of desiccant 28, forming a part of the breather
apparatus 29 of this invention. Connected to one end of the column
of desiccant 28 is a capillary tube 30. Capillary tube 30 extends
through an eyelet or grommet 34 supported in aligned apertures 36
in desiccant tube 32 and the web 20 of spacer channel 16. Eyelet or
grommet 34 clinches tube 32 to web 20.
As best shown in FIG. 3, desiccant tube 32 is an elongated tube
filled with a desiccant 28, such as silica gel. The tube 32 is
shown closed at its upper end with a small piece of
moisture-resistant, air-impermeable mastic 38 and at its lower end
with a piece of air-permeable felt 40 or the like. Capillary tube
30 is fixed in place with an end portion 42 connected to or in
communication with desiccant column 28 by means of a layer or bead
of moisture-resistant, air-impermeable mastic 44 adhered or bonded
to tube end portion 42, the web 20 of spacer channel 16, the
peripheral edges of the glass sheets 12 and 14 and marginal edge
portions of the outer faces of the glass sheets. The free end 46 of
capillary tube 30 extends downwardly, outside the layer of mastic
44, for a length of about 3 to 12 inches to help minimize moisture
vapor diffusion during breathing. A capillary tube 30 having an
inside diameter of about 0.025 inch has been found to be
satisfactory.
Channeling 48 of essentially U-shaped cross-section extends
completely around the perimeter of the unit to protect its edges
and to protect capillary tube 30. Channeling 48 is comprised of
several channel sections that are joined or butted together at
their ends. As shown, the free end 46 of capillary tube 30 resides
in a space 50 defined between mastic layer 44 and the web 52 of
channeling 48. Since, in the embodiment shown, channeling 48 is
comprised of butted channel sections, air may ingress of egress
through these butt joints and pass through capillary tube 30 and
desiccant column 28 to permit the insulating space between glass
sheets 12 and 14 to breathe.
FIG. 4 depicts a cross-section of another embodiment of this
invention. In this embodiment, in lieu of dehydrator element 24,
bags of desiccant 54 (one of which is shown) are placed in spacer
channel 16, the channel 16 is filled with an air permeable material
56, such as fiber glass or polyurethane foam and the channel is
closed with a perforated or foraminous metal strip 58. In all other
respects and, in particular, with regard to the breather device 29
of this invention, the construction of the embodiment of FIG. 4 is
identical to that of FIGS. 1 to 3.
EXAMPLE
The following deals with a means of determining the length of the
desiccant column required for a multiple-glazed breather window of
this invention.
Statistically, it has been determined that for a maximum number of
design conditions the minimum amount of desiccant required is that
needed to adsorb the moisture entering the unit at 85.degree. F and
50 percent relative humidity for one air space volume change
created by a barometric change of 1.0 inch of mercury and a
10.degree. F change in air temperature. Accordingly, consider a
unit 74 inches .times. 90 inches with a 4 inch air space. Using the
perfect gas equation:
V.sub.2 = (V.sub.1 .times. T.sub.2 .times. P.sub.1)/(T.sub.1
.times. P.sub.2)
where
V.sub.1 = original air space volume = 74 inches .times. 90 inches
.times. 4 inches/1728 = 15.42 ft.sup.3
T.sub.1 = original sealing temperature = 75.degree. F
P.sub.1 = original sealing pressure = 30.5 inches of mercury
V.sub.2 = design volume
T.sub.2 = design temperature = 85.degree. F
P.sub.2 = design pressure = 29.5 inches of mercury
V.sub.2 = 16.24. Therefore, .DELTA.V = V.sub.2 - V.sub.1 = 0.82
ft.sup.3
Air density = 0.07285 pounds of dry air/ft.sup.3
Pounds of dry air/.DELTA.V = 0.82 .times. 0.07285 = 0.05974
pounds
Humidity ratio = 0.013 pounds of water/pound of dry air
Pounds of water/.DELTA.V = 0.0594 .times. 0.013 = 0.000776
pounds
Silica gel adsorbs four percent of its weight at 0.degree. F dew
point. The minimum amount of silica gel required for one air space
volume change is:
Silicia gel = (0.000776 .times. 454)/0.04 = 8.808 grams
A 1/4 inch .times. 1/4 inch tube contains 1.22 grams of silica gel
per inch.
Minimum length of desiccant column = 8.808/1.22 = 7.2 inches
It is recommended that a safety factor of 10 be used and,
therefore, a column of desiccant of 7.2 .times. 10 = 72 inches is
required. Accordingly, the recommended amount of desiccant required
in a breather column is that amount which will adsorb 10 times the
quantity of moisture entering the unit from one air space volume
change based on the specified design conditions.
Although the foregoing disclosure has been made in connection with
acoustical window units, it should be apparent that the breather
device of this invention may be used with other multiple-glazed
units as well. Acoustical multiple-glazed units were selected for
this disclosure because, due to their larger enclosed volume than
standard units, e.g., up to 1 inch thick, they are more susceptible
to breakage if they are not provided with a breather device. Also,
it should be understood that the glass sheets or glass panels of a
typical, transparent, multiple-glazed unit of the invention may be
clear, tinted (colored), coated or coated and tinted. In connection
with transparent tinted, coated or coated and tinted glass, an
advantage of the use of the breather device of this invention is
that it keeps the glass sheets or panels flat regardless of changes
in atmospheric conditions. Bowed glass, resulting from a pressure
difference between the inside and the outside of a multiple-glazed
unit, causes light to reflect unevenly, thus distorting the
uniformity of appearance and color of a unit. By maintaining the
glass flat with the use of the breather device of this invention,
the uniformity of appearance and color of a multiple-glazed unit,
particularly a unit having an outer glass sheet coated with a
transparent reflective film, is greatly enhanced.
Although the present invention has been described with particular
reference to the specific details of certain embodiments thereof,
it is not intended that such details shall be regarded as
limitations on the scope of the invention except insofar as
included in the accompanying claims.
* * * * *