U.S. patent application number 11/507744 was filed with the patent office on 2008-02-28 for vents for temporary shelters and coverings.
This patent application is currently assigned to General Electric. Invention is credited to Vishal Bansal, Clare R. King.
Application Number | 20080047596 11/507744 |
Document ID | / |
Family ID | 38819751 |
Filed Date | 2008-02-28 |
United States Patent
Application |
20080047596 |
Kind Code |
A1 |
King; Clare R. ; et
al. |
February 28, 2008 |
Vents for temporary shelters and coverings
Abstract
A venting system for a temporary shelter that includes one or
more vents that are positioned in the exterior shell of the
temporary shelter. Each of the one or more vents may include a
membrane that is moisture vapor transmissive and resistant to
liquid penetration. The membrane may have a moisture vapor
transmissive rate of at least 4,000 g/m.sup.2/day. The membrane may
be expanded polytetrafluoroethylene. The one or more vents may have
a size such that there is approximately 4 m.sup.2 of vent surface
area in the exterior shell of the temporary shelter per 20 m.sup.3
of interior space within the temporary shelter.
Inventors: |
King; Clare R.; (Providence,
RI) ; Bansal; Vishal; (Overland Park, KS) |
Correspondence
Address: |
GE ENERGY GENERAL ELECTRIC;C/O ERNEST G. CUSICK
ONE RIVER ROAD, BLD. 43, ROOM 225
SCHENECTADY
NY
12345
US
|
Assignee: |
General Electric
|
Family ID: |
38819751 |
Appl. No.: |
11/507744 |
Filed: |
August 22, 2006 |
Current U.S.
Class: |
135/93 |
Current CPC
Class: |
E04H 15/14 20130101 |
Class at
Publication: |
135/93 |
International
Class: |
E04H 15/14 20060101
E04H015/14 |
Claims
1. A venting system for a temporary shelter, comprising: one or
more vents positioned in an exterior shell of the temporary
shelter; wherein each of the vents include a membrane that is
moisture vapor transmissive and resistant to liquid
penetration.
2. The system of claim 1, wherein the membrane comprises a moisture
vapor transmissive rate of at least 4,000 g/m.sup.2/day.
3. The system of claim 1, wherein the one or more vents comprise a
laminated fabric that includes the membrane and a base fabric.
4. The system of claim 3, wherein the base fabric comprises a
woven, non-woven or knit textile.
5. The system of claim 3, wherein the base fabric comprises a flame
retardant material.
6. The system of claim 1, wherein the membrane is air permeable and
immune to liquid penetration.
7. The system of claim 1, wherein at least one of the vents is
positioned in the upper part of a side of the temporary
shelter.
8. The system of claim 1, wherein the membrane is oleophobic.
9. The system of claim 1, wherein the membrane comprises expanded
polytetrafluoroethylene.
10. The system of claim 1, wherein the one or more vents are
incorporated into the temporary shelter by a waterproof zipper.
11. The system of claim 1, wherein each of the one or more vents is
welded onto a corresponding opening in the exterior shell of the
temporary shelter.
12. The system of claim 1, wherein each of the one or more vents is
stitched directly onto a corresponding opening in the exterior
shell of the temporary shelter and seam tape is used to seal the
stitch holes from water leaks.
13. The system of claim 1, wherein the one or more vents comprise a
size such that there is approximately 4 m.sup.2 of vent surface
area in the exterior shell of the temporary shelter per 20 m.sup.3
of interior space within the temporary shelter.
14. A structure for enclosing items, such as people or equipment,
capable of generating heat or humidity, said structure comprising:
an exterior wall; and one or more vents incorporated in the
exterior wall, the one or more vents comprising a membrane that is
moisture vapor transmissive to permit release of heat or humidity
from within the structure and resistant to liquid penetration.
15. The structure of claim 14, wherein the one or more vents
comprise a size such that there is approximately 4 m.sup.2 of vent
surface area in the exterior wall of the structure per 20 m.sup.3
of interior space within the structure.
16. The structure of claim 14, wherein the membrane is
oleophobic.
17. The structure of claim 14, wherein the membrane is air
permeable and immune to liquid penetration.
18. The structure of claim 14, wherein the membrane comprises
expanded polytetrafluoroethylene.
19. The structure of claim 14, wherein the membrane comprises a
moisture vapor transmissive rate of at least 4,000
g/m.sup.2/day.
20. The structure of claim 14, wherein a positive air pressure is
maintained in the structure.
Description
TECHNICAL FIELD
[0001] This present application relates generally to improved vents
for temporary shelters and coverings. More specifically, but not by
way of limitation, the present application relates to systems for
providing breathable, water resistant membrane vents in temporary
shelters or coverings to prevent humidity or heat build-up.
BACKGROUND OF THE INVENTION
[0002] Temporary shelters, such as tents, temporary sheds, mobile
military structures, typically are made from non-breathable fabrics
or membranes. Because of the metabolic breathing process of
occupants as well as other activities, such as cooking, occupation
of these structures causes humidity build-up. Humidity build-up may
create an uncomfortable condition for the occupants, condensation
issues, damage to electrical equipment by water, and other
problems. Further, coverings for electrical equipment and other
types of equipment, such as weapons, automobiles or aircraft, may
experience humidity or heat build-up, either from heat generation
within the cover by the equipment or by exposure to the sun coupled
with moisture.
[0003] Certain types of vents have been employed in temporary
shelters and coverings to vent built-up humidity or heat to the
atmosphere. However, conventional vents often employ mesh, which is
susceptible to water penetration. More specifically, mesh and other
similar vent materials allow water to enter the temporary shelter
or covering, which may be uncomfortable to the occupants, lead to
issues with electrical equipment housed therein or cause other
problems. The problem also has been solved with the use of electric
dehumidifiers. However, temporary shelters often are located in
remote areas where electric service is unavailable.
[0004] Thus, there is a need for improved venting systems in
temporary shelters and covering. Such improved venting systems will
allow for excess water vapor to be vented to the atmosphere while
preventing the penetration into the temporary structure of
undesirable external conditions, such as water, dust, sand,
insects, wind, microbes and the like.
BRIEF DESCRIPTION OF THE INVENTION
[0005] The present application thus may describe a venting system
for a temporary shelter that includes one or more vents that are
positioned in the exterior shell of the temporary shelter. Each of
the one or more vents may include a membrane that is moisture vapor
transmissive and resistant to liquid penetration. The membrane may
have a moisture vapor transmissive rate of at least 4,000
g/m.sup.2/day.
[0006] The one or more vents may include a laminated fabric that
includes the membrane and a base fabric. The base fabric may
include a woven, non-woven or knit textile. The base fabric may
include a flame retardant material.
[0007] In some embodiments, the membrane may be air permeable and
immune to liquid penetration. At least one of the vents may be
positioned in the upper part of a side of the temporary shelter. In
some embodiments, the membrane may be oleophobic. The membrane may
be expanded polytetrafluoroethylene.
[0008] In some embodiments, the one or more vents may be
incorporated into the temporary shelter by a waterproof zipper. In
other embodiments, each of the one or more vents may be welded onto
a corresponding opening in the exterior shell of the temporary
shelter. In other embodiments, each of the one or more vents may be
stitched directly onto a corresponding opening in the exterior
shell of the temporary shelter and seam tape may be used to seal
the stitch holes from water leaks. The one or more vents may have a
size such that there is approximately 4 m.sup.2 of vent surface
area in the exterior shell of the temporary shelter per 20 m.sup.3
of interior space within the temporary shelter.
[0009] The present application may further describe a structure for
enclosing items, such as people or equipment, capable of generating
heat or humidity. The structure may include an exterior wall and
one or more vents incorporated in the exterior wall. The one or
more vents may include a membrane that is moisture vapor
transmissive to permit release of heat or humidity from within the
structure and resistant to liquid penetration. The one or more
vents may have a size such that there is approximately 4 m.sup.2 of
vent surface area in the exterior wall of the structure per 20
m.sup.3 of interior space within the structure.
[0010] In some embodiments, the membrane may be oleophobic. The
membrane further may be air permeable and immune to liquid
penetration. The membrane may be expanded polytetrafluoroethylene.
The membrane may have a moisture vapor transmissive rate of at
least 4,000 g/m.sup.2/day. In some embodiments, a positive air
pressure may be maintained in the structure. These and other
features of the present application will become apparent upon
review of the following detailed description of the preferred
embodiments when taken in conjunction with the drawings and the
appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a perspective view of an exemplary temporary
shelter with vents in accordance with exemplary embodiments of the
present invention.
[0012] FIG. 2 is a schematic sectional view of a laminated fabric
that includes a composite membrane which may be used in accordance
with certain embodiments of the present invention.
[0013] FIG. 3 is an enlarged schematic plan view of a portion of
the membrane illustrated in FIG. 2, viewed approximately along the
line 2-2 in FIG. 2.
DETAILED DESCRIPTION OF THE INVENTION
[0014] FIG. 1 illustrates a perspective view of a tent or temporary
shelter 2 in which exemplary embodiments of the present application
may be used. The temporary shelter 2 may include an exterior fabric
or shell 3 that is supported by two flexible, crossing rods 4 such
that the temporary shelter 2 has four sides and an approximate dome
shape. Those of ordinary skill in the art will recognize that the
configuration of temporary shelter 2 is exemplary only and that
other tent or temporary shelter configurations may be used with the
invention described herein. Further, one of ordinary skill in the
art will recognize that the inventive concepts described in
relation to the temporary shelter 2 may be readily applied to other
types of coverings, such as coverings for electrical equipment,
weapons, automobiles or aircraft, that may experience heat or
humidity build-up. Thus, for the sake of simplicity, exemplary
embodiments will be discussed in relation to the temporary shelter
2 example, though it will be appreciated that the embodiments may
be used with other types of tents, temporary shelters, and other
coverings.
[0015] The temporary shelter 2 may include a door 6 for egress,
which may zipper between and open and closed position. The
temporary shelter 2 further may include one or more vents 8. The
vents 8 may be made of a laminated fabric that includes a
breathable, water-resistant or waterproof membrane. The vents 8
thus may allow water vapor to be vented to the atmosphere while
being resistant or immune to water penetration, as described in
more detail below. The vents 8 may be located in the exterior shell
3 of the temporary shelter 2. As shown, it may be advantageous to
locate the vents 8 in the upper part (i.e., the top third) of each
of the sides of the temporary shelter such that the warmer, more
humid air inside the temporary shelter 2 is vented to the
atmosphere. In some embodiments, as depicted in FIG. 1, the
temporary shelter 2 may include rectangular vents 8 that are
located in the upper part of each of its sides.
[0016] The membrane of the vent 8 may be: 1) breathable, including
moisture vapor transmissive and 2) resistant or immune to liquid
penetration (which, in combination, is often referred to as
"waterproof breathable"). In some embodiments, the vent 8 maybe air
permeable. In general, "moisture vapor transmissive" is used to
describe a membrane that readily permits the passage of water
vapor. In some embodiments of the current application, the moisture
vapor transmissive rate ("MVTR") of the membrane is at least 4,000
g/m.sup.2/day (as tested per JIS L 1099 B-2 procedures). The term
"immune to liquid penetration" is used to describe a membrane that
is not "wet" or "wet out" by a challenge liquid, such as water, and
prevents the penetration of liquid through the membrane under
varying ambient conditions.
[0017] In one embodiment, the vent 8 of the present application may
include a membrane that is made from expanded
polytetrafluoroethylene ("ePTFE"). In general, an ePTFE membrane is
air permeable and moisture vapor transmissive, yet resistant or
immune to liquid penetration at moderate pressures. FIG. 2
demonstrates a cross-section of an exemplary ePTFE laminated fabric
10, which may be used according to exemplary embodiments of the
present application. The ePTFE laminate fabric 10 may include an
ePTFE membrane 12 and a shell or base fabric 14. The ePTFE membrane
12 may include a membrane 16. The ePTFE membrane 12 is typically
laminated to the base fabric 14 to create the ePTFE laminate fabric
10. The ePTFE membrane 12 and the base fabric 14 may be laminated
pursuant to a thermal lamination process, adhesive lamination
process, or other conventional methods. The base fabric 14 may be
laminated to one side for both sides of the ePTFE membrane 12. The
base fabric 14 may be a woven, nonwoven or knit textile.
[0018] As demonstrated in FIG. 3, the membrane 16 of the ePTFE
membrane 12 may be porous, and preferably microporous, with a
three-dimensional matrix or lattice type structure of numerous
nodes 22 interconnected by numerous fibrils 24. Surfaces of the
nodes 22 and fibrils 24 may define numerous interconnecting pores
26 that extend through the membrane 16 between opposite major sides
18, 20 of the membrane. ePTFE membranes are more fully described in
U.S. Pat. Nos. 6,228,477; 6,410,084; 6,676,993; 6,854,603; and U.S.
Published Patent Application U.S. 2004/0059717, which are
incorporated herein in their entirety. In some embodiments, the
membrane 16 may be oleophobic. Those of ordinary skill in the art
will appreciate that the description herein of the specific ePTFE
membrane 12 is exemplary only and that other types of membranes may
be used with the exemplary embodiments described herein. For
example, such similar membranes may include microporous or
non-microporous polyolefins, polyurethanes, polyesters, polyamides,
polyethersulfones, cellulose acetate and the like.
[0019] As stated, the vents 8 may be made of a laminated fabric
that includes a membrane. Further, according to certain
embodiments, the laminated fabric may be the ePTFE laminated fabric
10 that includes an ePTFE membrane 12. The ePTFE membrane 12 may be
laminated to the base fabric 14, which may be chosen for its
strength (tensile and tear strength), durability, durability
against ultraviolet radiation, ability to block-out light, flame
retardant characteristics, softness, drapeability, and ability to
seamseal. Thus, for example, the base fabric 14 may be made of
polyamides, polyesters, polyolefins or other similar materials.
Flame retardant fibers, such as Nomex.RTM. also may be blended into
the base fabric 14. As described, the base fabric 14 may be
laminated on one or both sides of the ePTFE membrane 12 pursuant to
the processes described above.
[0020] The vents 8 may be integrated into the sides of the
temporary shelter 2 by several means. In some embodiments,
waterproof zippers may be attached to the periphery of the vent 8
and onto the corresponding opening in the exterior shell 3 of the
temporary shelter 2. The vent 8 then may be zipped into place. This
method of integration may allow for the easy replacement of worn or
damaged vents 8. In other embodiments, the vent 8 may be stitched
directly into the exterior shell 3 of the temporary shelter 2. Seam
tape or other similar material may be used to seal the stitch holes
from water leaks. In other embodiments, the vents 8 may be weld
onto the corresponding openings in the exterior shell 3. Any of the
known processes for imparting energy for completed the weld may be
used, such as ultrasonic, radio frequency, hot air gun, hot plate
and the like.
[0021] The vents 8 may be sized in the temporary shelter 2 so that
the vents 8 perform efficiently while also being cost effective.
More specifically, the vents 8 may be sized to a minimum size at
which the vents 8 maintain a comfortable humidity level within the
temporary shelter 2 assuming a certain level of occupation. In this
manner, the vents 8 are not sized too large, which might be
wasteful from a cost perspective, or sized too small, which might
not be able to maintain a comfortable humidity level within the
temporary shelter 2. Given these competing criteria, it has been
discovered that an efficient size for the vents 8 is approximately
4 m.sup.2 of vent surface area in the exterior shell of the
temporary shelter 2 per 20 m of interior space within the temporary
shelter 2. This sizing assumes an occupancy rate of approximately
one person per 10 m.sup.3 of interior space.
[0022] Accordingly, if the vent sizing ratio of approximately 4
m.sup.2 of vent surface area in the exterior shell of the temporary
shelter 2 per 20 m.sup.3 of interior space within the temporary
shelter 2 is maintained, the relative humidity will not exceed
comfortable levels. For example, it has been discovered that in a
hot, dry desert environment, given the parameters and occupancy
rate described above, the relative humidity will stabilize at about
60-70% if the vents 8 are included at the described vent sizing
ratio (i.e., approximately 4 m.sup.2 of vent surface area in the
exterior shell of the temporary shelter 2 per 20 m.sup.3 of
interior space within the temporary shelter 2). Note this example
assumes that the inside temperature of the temporary shelter 2 is
maintained at 25.degree. C. and that the outside conditions include
a temperature of 45.degree. C. and 10% relative humidity. If, given
the occupancy rate described above. the vents 8 were not included
in this example, the relative humidity inside the temporary shelter
2 would exceed 100% in approximately one hour.
[0023] To take another example, it has been discovered that in a
cold, wet environment, given the parameters and occupancy rate
described above, the relative humidity will stabilize at about
40-50% if the vents 8 are included at the described vent sizing
ratio (i.e., approximately 4 m.sup.2 of vent surface area in the
exterior shell of the temporary shelter 2 per 20 m.sup.3 of
interior space within the temporary shelter 2). Note this example
assumes that the inside temperature of the temporary shelter 2 is
maintained at 25.degree. C. and that the outside conditions include
a temperature of -10.degree. C. and 60% relative humidity. If,
given the occupancy rate described above, the vents 8 were not
included in this example, the relative humidity inside the
temporary shelter 2 would exceed 100% in approximately one hour.
Note that in some alternative embodiments the vents 8 may be sized
smaller or larger than the ratio described above. Further, in other
alternative embodiments, a positive air pressure may be maintained
in the temporary shelter 2 pursuant to conventional means. The
positive air pressure may aid with the egress of moisture vapor
through the vent 8.
[0024] From the above description of preferred embodiments of the
invention, those skilled in the art will perceive improvements,
changes and modifications. Such improvements, changes and
modifications within the skill of the art are intended to be
covered by the appended claims. Further, it should be apparent that
the foregoing relates only to the described embodiments of the
present application and that numerous changes and modifications may
be made herein without departing from the spirit and scope of the
application as defined by the following claims and the equivalents
thereof.
* * * * *