Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
1~7~925
1 This application is a divisional of application 284,637
filed August 9, 1977.
- Background of the Invention
;- The present invention relates generally to floating
covers and particularly to a laminated material for reservoirs
-~ forming floating covers for liquid reservoirs.
Floating covers for contained fluids, generally speaking,
are well known in the prior art. Some of this art is directed
- towards fluids contained within a tank or vessel rather than a
:,,
fluid to be contained in a reservoir. Numerous patents such as
United States Patent Nos. 3,228,702; 1,775,758; 1,712,321;
3,343,70~; 3,016,814 are directed towards providing seals for
floating coverings that engage the sides of a suitable tank.
Similarly, United States Patent Nos. 3,159,301 and 3,557,994 are
directed towards floating diaphragms adapted to be used in various
pressure tanks. Other non-floating types of diaphragm covers for
tanks are disclosed in United States Patent Nos. 1,917,623 and
3,028,040. However, all of such prior art is directed towards
, .~
floating structures that are contained within a substantially en-
~~ 20 closed housing such as a tank or vessel. Such floating covers are
;~ not exposed to the adverse environmental conditions such as wind,
ice and water accumulations on the surfaces thereof as well as the
; problems incumbent in providing floating structures for large
expansive reservoirs rather than comparatively small storage tanks.
; Floating covers, such as disclosed in United States ~-
Patent Nos. 3,462,040; 3,592,009; and, 3,740,902, have long been
~ in use. However, a recurring problem that has plagued r~servoir
,- covers of the prior art is how to control the tension of the
floating cover on the fluid while accommodating fluid elevational
- changes in a reservoir having sloping or tapered surfaces adjacent
reservoir peripheries. In United States Patent Nos. 2,986,302 and -
3~079f030~ movable segmented sections are used to support the
- 1 - .
:
.
. -~ - - , : , :
: . : . . ~- . :
.
: ' . : ~ ', ' :
: ~799~5
.
';' 1 floating cover as the fluid level experiences elevational
' variations. United States Patent 3,330,118 discloses the use
of a plurality of circular floaters for supporting the cover of
~ a sunken tank as the fluid varies in elevation while U.S. Patent
'~ No. 2,970,716 uses multiple sections in combination with pontoons
.
to support the floating roof for an oil storage reservoir.
... .
United States Patent No. 3,815,367 discloses the use of
' a complex tensioning line-arrangement for providing for the proper
,, tension of a floating cover assembly for a reservoir to insure:,~
,. 10 biasing thereof. Further, the present inventor disclosed in
United States Patent Nos. 3,313,443 and 3,667,641 floating cover,
,, arrangements which provide for a variety of drain configurations
' to prevent unwanted accumulation of liquid on the upper surface
~- of such a liquid storage reservoir cover in an effort to prevent
. .
,~'' damage due to the weight of unwanted liquid on the upper surface
' of the cover and/or the detrimental environmental effects due to
,j freezing and the like. Further, United States Patent No.
~,~ 3,736,754 discloses a combination two-cover assembly wherein one
~: cover is used to float on the surface of the stored liquid while
"," 20 another roof is inflated thereover for protection of the floating
~,~ roof. This dual roof assembly not only is expensive but requires
... .
~- maintenance on both the floating cover as well as the inflatable
~i roof.
Not only is it important that a floating cover have the
, proper tension thereon to prevent damage thereto as a result of
, high wind and/or water accumulations thereon, but also it is
~', important to provide for ease in reservoir maintenance thereof
` without necessitating removal of the cover. Typically, prior art
~' repairs and other reservoir maintenance was accomplished by divers
~, 30 submerged in the reservoir fluid below the reservoir cover.
However, no provisions are made in the prior art for providing an
.
0~992S
1 effective system of maintenance and repair of both the floating
cover as well as the storage reservoir in combination with means
.~ for compensating for elevational changes of the fluid within the
reservoir while providing the necessary tension on the reservoir
cover.
. A-lso, in the prior art, flexible and/or inflatable
~:' structu~ have been used for a wide variety of applications which
-~ include use in a variety of shelter or building configurations
such as those disclosed in United States Patent Nos. 3,924,363;
3,626,836; and 3,885,360 as well as an inflatable covering for
.;, swimming pools as disclosed in United States Patent No. 3,918,221
and collapsible dams and damming methods as disclosed in United
States Patent No. 3,834,167.
Although these relate generally to inflatable structures,
these are of little consequence in considering the requirements
.~ that must be met by a reservoir cover that must not only float
- on the surface of the reservoir fluid having a required tensioning
thereof but also have appropriate provisions for ease in
. . .
reservoir or cover maintenance.
.; .
Summary of the Invention
In one of its aspects the invention provides a laminated
.'~ floating cover material adapted to float on the liquid stored in
-: a storage reservoir, comprising a reinforced upper layer adapted
,. . .
. to be exposed to adverse environmental conditions without deteriora-:
: tion thereof, and, a lower layer mounted with said upper layer
and in contact with the stored liquid, said lower layer capable
- of floatably supporting itself and said upper layer on the stored
: liquid without deterioration of said lower layer and capable of
insulating the stored liquid from adverse environmental
conditions.
. ~ _ 3 _
:' ' '
'
:
,
:
, : . , :
,, : -
799~S
.
1 In another of its aspects, the invention provides a
: lightweight laminated flexible floating cover material for float-
' ing on a liquid stored in a storage reservoir or ballooning
when inflated with a relative low pressure of 1-3 pounds per
, square foot to provide access to the storage reservoir, comprising:
a reinforced upper layer formed of a sulfochlorinated poly-
. ethylene adapted to be exposed to adverse environmental conditions
: without deterioration thereof, said upper layer having a flexible
, polyester reinforcement to add strength to said upper level;
j~ 10 a lower layer formed of a closed cell polyethylene foam
.- laminated with said upper layer and in contact with the stored
:
;. liquid, said lower layer capable of floatably supporting itself
and said upper layer on the stored liquid without deterioration
~.~ of said lower layer and capable of insulating the stored liquid
.. from adverse environmental conditions; and
said laminated upper and lower layers formed of lightweight
(~ flexible material for ballooning above the reservoir when the
.~; cover material is inflated with a relative low pressure of 1 to
3 pounds per square foot to provide maintenance access to the
storage reservoir.
,, .
.'',~ ,
, - .
," :
. . .
- 30
-3a-
'~ g
,
;
7~9ZS
1 Brief Description of the Drawings
i Fig. 1 is an isometric view of the floating cover
assembly;
Fig. 2 is an isometric, sectional view of the sheet
adapted to float on the surface of the stored liquid of the
.:
liquid storage reservoir, of the floating cover assembly;
.~
Fig. 3 is a schematic elevational view of the liquid
storage reservoir having the floating cover assembly for
maintenance of the sheet and/or reservoir;
Fig. 4 is an elevational view of the floating cover
-, assembly showing ballasting of the sheet during maintenance
- operations;
Fig. 5 is an elevational view of the floating cover
~i assembly, showing tensioning of the sheet to eliminate formation
- of wrinkles in the sheet when floating on the surface of the
level-varying liquid-stored in the reservoir;
, Fig. 6 is a sectional side view of the floating cover
assembly having a center ballasted pneumatic support column;
Fig. 7 is a view similar to Fig. 6 and illustrating a
~-, ! .
- plurality of ballasted pneumatic support columns;
. :
Fig. 8 is a sectional side view of the ballasted
pneumatic support column;
,. . .
~, Fig. 9 is an isometric view of the floating cover in
the inflated condition;
Fig. 10 is a sectional side view of a drain sump of
; the floating cover; and
_ 4 _
. .
-
:
-, :
.,,., ~.
7~9Z5
.:'
;
...
1 Fig. 11 is a sectional side view of another form of
drain sump.
Description of the PreEerred Embodiment
;~ Referring to the drawings, the letter C designates the
; floating cover assembly. The floating cover assembly C includes
`~-' a sheet S adapted to be secured to a reservoir R by securing means
M with the sheet S having envelope means E formed therewith for
'~ covering the liquid storage reservoir R.
;~.
The floating cover assembly C is adapted to be used in
conjunction with a liquid storage reservoir R. Such liquid
storage reservoirs R are well known in the art and may be of a
variety of sizes and shapes as well as types of construction.
As shown shchematically in Fig. 3, the reservoir R may be formed
~r'', of an excavated portion of a tract of land such that the reservoir
R includes a reservoir floor 10, side walls 12 and berm 14.
.. :. .
Although the side walls 12 are illustrated as being inclined,they
may be arranged vertically or otherwise formed as desired. The
reservoir floor 10, side walls 12 and berm 14 may be formed of
earth as shown in Fig. 3 or may have concrete wrappers lOa, 12a,
~; 20 14a, respectively (Figs. 4, 5). Alternatively, the wrappers
lOa, 12a, 14a may be of metal or any other suitable material.
~ The reservoir floor 10 will ordinarily be flat as shown in Fig. 3
;~ and additionally, the inner surface of the reservoir may be lined
5"" with suitable fluid-impervious material such as a liner (not
shown) formed of a flexible sheet material such as a rubber-coated
fabric, multi-ply butyl rubber, nylon, polyvinyl chloride, or
the like.
The liquid L to be stored in the liquid storage
-. reservoir R may be supplied to and withdrawn from the reservoir
R by any suitable or conventional means (not shown) and will
normally be maintained at a predetermined level no greater than
5 -
.''.' " ' .
,, .
., ,
1~799Z5
,
1 the maximum level 16 (Fig. 3). The predetermined level may vary
as described more fully hereinbelow. Such normal level variations
will,of course, be determined by the anticipated supply and re-
moval of the stored liquid L for which the reservoir R is pro-
vided and may differ in every installation.
The cover assembly C of the present invention includes a
sheet S. The sheet S is preferably formed of a flexible material
which is impervious to the stored liquid L and will not be attacked
by nor deteriorate in the presence of the stored liquid L in the
reservoir R. Further, it is desired that the sheet S be adapted to
.'' float on the surface of the stored liquid L. Preferably, the sheet
S may be formed of a laminated rubber or plastic cover material 18
~ .
as shown in Fig. 2. The laminated cover material 18 is preferably
formed of an upper layer 18a and a lower layer 18b mounted there-
; with and which may be formed of different rubber or plastic
materials. Preferably, the upper layer 18a is adapted to be ex- - ;
posed to the adverse environmental conditions surrounding the
reservoir R, such as rain, wind, ice, heat and the like without
j deterioration thereof. Preferably, the upper layer 18a is formed
of a material such as that sold under the trademark "Hypalon",
by the Dupont Company, further having a reinforcement filament
18c formed of polyester to add strength to the upper layer 18a.
Preferably, the lower layer 18b is formed of a closed cell
polyethylene foam with the lower layer 18b being laminated to
upper layer 18a at interface 18d. As such, the lower layer
18b acts to floatably support itself as well as the upper
layer 18a on the stored liquid L within the reservoir R.
Typically, the stored liquid L is water, however, the reservoir
R may contain oil, hydrocarbons or other liquids and
consequently, the sheet S must be appropriately formed
-- -- 6 --
-
.
~ , .
` 107~92S
. . . .
1 of a material that is not only impervious to the stored liquid
~ L but-also will float on such liquid.
c The floating roof material 18 is selected and designed
, .
~' to-be inflated as well as to float. The material must also be
lightweight to balloon when inflated with a relatively low air
, . .
pressure in the range of 1-3 lbs. per square foot. The con-
tinuous form layer will prevent a section of the roof to sink
if the material 18 is inadvertently punctured and will also serve
~- to insulate the water in the reservoir from undesired extremes
`; 10 of cold and heat.
The sheet S includes a peripheral edge 20 adapted to
l; ~
,-~ be secured to the berm 14 of the reservoir R by securing means M.
;~y~ The securing means M may include an appropriate cleat or fastener
~,;;,. -, ~
22 which may be embedded in the concrete wrapper 14a of the
berm 14 for securing the sheet S thereto adjacent the peripheral
~' edge 20 thereof. The sheet S for the reservoir R should have
an area which is greater than the area of the reservoir R where
;, the securing means M for the sheet S are located.
The floatable cover assembly C of the present invention
,~ 20 further includes envelope means E formed with the sheet S at
; least adjacent a portion of the peripheral edge 20 and preferably
~; of the cover material 18. The envelope means E includes
envelope 24 formed of an upper portion 24a and a lower portion
24b which preferably is formed of the same material as the
~:;
; laminated cover material 18. The envelope means E is preferably
~ located adjacent the berm 14 of the reservoir R therebetween
.~,j,.
' the peripheral edge 20 of the sheet S and the interior cover
.;:
;- portion 26 at the marginal edge 26a thereof. It should be
:: .
` recognized that if there should be a portion of the sheet S
; 30 not having an envelope means E therewith, then the marginal edge
,, .
- 7 -
:,'
: :~,, .
. "
:~"
::'
"
.... .
- ~ 10799~5
1 26a of the sheet S will act as the peripheral edge 20 to be
secured to the berm 14 and fasteners 22 therewith. Alternatively,
~ if the envelope means E is in fact therebetween the marginal
; edge 26a of the interior cover portion 26 and the peripheral
edge 20, then the- envelope means E will preferably be formed
.- - as shown in Figs. 4 and 5 of portions 24a, 24b. The upper
.
portion 24a and lower portion 24b are appropriately affixed or
bonded to the marginal edge 26a in fluid-tight engagement
!r
- adjacent the bonding edge schematically represented at 28
(Figs. 4, 5). Similarly, upper portion 24a and lower portion
. .~ . .
24b of envelope 24 are bonded or suitably affixed theretogether
in fluid-tight engagement adjacent the peripheral edge 20
at schematic location 30.
. .
The envelope means E is further formed having at least
.. . ;.
;~ - one inlet port 32 and at least one outlet port 34. The ports
32, 34 are adapted to be opened and closed and in the closed
position, provide a fluid-tight seal with the interior portion
. .
- ~ 36 of the envelope means E.
Valve means V is mounted with envelope means E pre-
ferably adjacent inlet port 32 in communication with the interior
portion 36 of the envelope means Æ. The valve means V acts
~ to regulate the amount of compressible fluid within the envelope
:~ means E as discussed more fully hereinbelow.
,,..~
'~ In the use or operation of one form of the cover assembly
C of the present invention, the cover assembly C is to provide
for proper tensioning of the floating sheet S wherein the
. surface level of the stored liquid in the liquid storage reservoir
R varies. The sheet S is disposed on the stored liquid L in
. .. ; - .
the reservoir R with the peripheral edge 20 being secured to
the berm 14 of the reservoir R by securing means M and having
~ 8 -
,.~
,
~ - :
' ' . . . .
.-:- .
` 1~799ZS
1 envelope means E therewith at least adjacent a portion of the
-i peripheral edge 20 of the sheet S. The envelope means E is
~ adapted to be filled with a compressible fluid such as air,
,~ .
, or any suitable gas, for expanding the envelope means E as shown
in Fig. 5. The expansion or ballooning action of the envelope
;.~ means E contracts the sheet S resulting in tensioning of the
~' interior cover portion 26 to eliminate the formation of wrinkles
:~ in the sheet S when floating on the surface of the level-varying
.. liquid stored in the reservoir R. Thus, the envelope means E
10 iS expanded in balloon-like fashion to result in a lateral
tensioning force on the sheet S tending to stretch the sheet S
' outwardly whereby wrinkles and cavities in the surface of the
sheet S will be reduced facilitating flow of rain and water from
.,:
'.; melting snow off of the sheet S towards an appropriate drain
;. during adverse environmental conditions while also preventing
pooling of fluid on the exterior surface thereof. The pre-
vention of wrinkles results in facilitating the removal of any
accumulation and retained liquid on the surface of the sheet S
which helps facilitate the reduction of stresses and strains
~ 20 on the laminated cover material 18.
,~. The envelope means E is inflated to a desired amount
, . . .
to ensure such proper, lateral tensioning of the sheet S to
eliminate the formation of wrinkles in the sheet S when floating
on the surface of the stored liguid L in the reservoir R. As
the liquid level varies, it may be necessary to add or remove
compressible fluid from within the envelope means E. As shown
in Fig. 5, the envelope means E is at a high level of stored
liquid L as indicated at position 38. Should the stored liquid
L level drop to that such as indicated at position 40, additional
laterial tension is effectuated upon the sheet S.. This increased
~, , .
- 107~9;25
1 lateral tension tends to flatten the envelope means E therefore
increasing the pressure of the compressible fluid within the
` interior portion 36 of the envelope means E. Should this
:
~; pressure increase overcome a predetermined pressure release
~ setting within the valve means V, the valve means V acts to re-
-~ ~ lease the excess pressure in a "pop-off" valve fashion to
` effectuate release of such excess pressure build-ups within the
envelope means E, but only reducing the pressure within the
` interior portion 36 to that of the predetermined amount.
' - 10 Thus, with the envelope means E in a position such as
that designated at 42 on stored liquid level indicated at 40,
the internal pressure within the interior portion 36 is sub-
stantially the same as that of the envelope means E as positioned
at the high level stored liquid position 38, while retaining
- substantially the same tensioning on the sheet S. This results
in the sheet S being of substantially a uniform tension while
the liquid level of the stored liquid in the reservoir R is
' of a changing nature.
,' Similarly, should the stored liquid L fall to a
position indicated at level 44, the tension on the sheet S
increases, further compressing the interior portion 36 of the
~:.
; envelope means E to such a position as noted at 46 wherein the
'~ valve means V again vents the excess pressure within the interior
:
portion 36 such that the appropriate non-compressible fluid
~`~ pressure within the envelope means E remains substantially the
same to insure a proper tensioning of the sheet S as the liquid ` `
continues to vary. Should the liquid level rise from that
, ~ of level 44 to that of level 40, it would be necessary to add
or increase the amount of compressible fluid within the envelope
means E by supplying such through inlet port 32 in an appropriate
,
-- 1 0
' . . .
,
: ~.
107~92S
1 fashion to thereagain assure proper tensioning of the sheet S.
i Further, it should be noted that the sheet S may have
v plural envelopes E about the peripheral edge thereof, shown
;~
schematically in Fig. 6 for sheets S having extremely large
surface areas and where one envelope means E is not sufficient
~ to provide the proper tensioning of such a sheet S.
!" The cover assembly C of the present invention may be
effectively incorporated for properly maintaining the liquid
storage reservoir R and sheet S for maintenance thereof should
0 the reservoir R and/or sheet S require maintenance thereof.
During such a maintenance operation, it is preferred that the
reservoir R be drained of stored liquid L by any appropriate
: ~ conventional means (not shown). Thereafter, the envelope means
E, as shown in Fig. 4, is appropriately filled through inlet
port 32 with any suitable non-compressible fluid 48 such as
water, or any other desired fluid resulting in the envelope
means E resting upon the concrete wrapping 12a of side walls 12
- dueto the weight of the fluid 48 within the envelope means E.
Thereafter, blower means B, which may be of any suitable high-
20 capacity blower 49 or the like, is connected with the sheet S
by port 50 and flexible hose 52 therebetween such port 50 and
the blower means B. The blower means B is appropriately en-
ergized resulting in the movement of compressible fluid, such
as air, from the blower means B under pressure through the
flexible hose 52 into port 50 and thereinto a cavity 54 formed
therebetween the reservoir R and the lower surface of the sheet
S, resulting in inflation of the sheet S which is heretofore
unsupported due to the stored liquid having been drained. The
blower means B results in the sheet S beiny inflated to permit
30 inspection and repair of the sheet S and cleanout of the storage
.~:
-- 11 --
99;~5
1 reservoir R. The envelope means E being filled with the non-
~ compressible fluid 48 acts as a ballast about the peripheral
;~ edge 20 of the sheet S to prevent the sheet S from flapping in
an unwielding fashion which could damage, tear, rupture and/or
destroy the sheet S while being in such an inflatably supported
position. It is desired that the sheet S be at substantially
the same elevation as the berm 14 of the reservoir R to prevent
any undue wind damage to the sheet S during such maintenance
operations. The reservoir R and the lower surface of the sheet
S may be accessed by an appropriate access hatch mounted with
- the sheet S. Thus, the sheet S and reservoir R may be duly
inspected, repaired or otherwise maintained without the need
of divers or other a~uatic gear which has heretofore been
~'., ',
,~ the maintenance procedure of the prior art.
Should the sheet S be of a significantly expansive
size, it may be necessary to provide one or more intermediate
ballasts 58 to prevent the sheet S from extending significantly
. thereabove the berm 14 of the reservoir R which could cause
-
wind damage to the sheet S. The intermediate ballast 58 may
include one or more ballast arrangements of any suitable size,
shape and/or weight in order that the sheet S may be kept
substantially the same as that of the elevation of the berm 14
~- of the reservoir R. The intermediate ballast 58 is preferably
of a plastic tube adapted to be filled with fluid such as water
so that the ballast may be positioned, then filled with water
during maintenance operations, and thereafter be drained to
i eliminate the need in moving heavy intermediate ballasts 58
about the sheet S prior to positioning same for proper maintenance
operations. `
The envelopes E as filled with fluid 48 help to
; - 12 -
. ,
`
C~9~5
; 1 keep a proper tensioning of the sheet S while being supported
by the fluid pressure generated by the blower means B and help
to prevent damage to the sheet S in its expanded, inflatably
; ~ supported configuration. For example, the sheet S as shown in
Flg. 4, upon draining of the reservoir R, results in the sheet
~- - overlying the concrete wrapping 12a of the sloping sides 12
- ~ of the reservoir R whereinafter being inflated, the sheet S
~ moves to a position such as that indicated by dotted lines at
-~ position 60 or in such a configuration as schematically shown in
Fig. 3. Thus, the cover assembly C of the present invention
~- provides for a method and apparatus for properly maintaining
.~- the reservoir R and sheet S during the maintenance operations
.; thereof. ~fter maintenance operations have been completed,
- preferably, the blower means B is removed and the non-compressible
fluid 48 is drained from the envelope means E by means of out-
i ,., ~.
let port 34 being released and/or the fluid 48 being pumped
outwardly from the interior portion 36 of the envelope means E
' through the inlet port 32 and outwardly therefrom. Thereafter,
t,'.~ ` the reservoir R is preferably again filled with liquid to be
- 20 stored therein and the sheet S is thereafter tensioned by in-
,;~ flating the envelope means E of the sheet S with a compressible
~ .
~ - fluid to thereafter tension the sheet S as it floatably overlies
. .
the stored liquid L in accordance with the hereinabove described
procedures to prevent the formation of wrinkles on the sheet S
~-~ for protecting the same.
; Thus, the cover assembly C of the present invention
- provides not only the means and method for appropriately
tensioning a sheet S on the stored liquid L of a storage reservoir
- R but also provides for ease of access, maintenance and repair
of the sheet S and reservoir R during maintenance operations
thereof.
- 13 _
, , .
,,
,, ~
. .
1()79925
; 1 Modified foam cover assembly of the present invention
is illustrated as C-l in Fig. 6 and 9 having a single center
ballast pneumatic support column, generally designated X
for both supporting and ballasting the sheet S when the cover
assembly C-l is in the inflated condition as illustrated. Another
modified cover assembly C-2 is illustrated in Fig. 7 having a
plurality of the ballasted pneumatic support columns X.
As best illustrated in Fig. 8, the ballasted pneumatic
. .
,1 support column X is secured to the underside of the sheet at
60. The support column X may be secured by sewing, glueing or
,- the like and as illustrated in Fig. 9 extends substantially
across the reservoir R.
.
The pneumatic support column X includes a lower
enclosed ballast chamber 62 and an upper pneumatic chamber 64.
The lower or ballast chamber 62 is formed of a material im-
pervious to water and preferably extends beyond the ends of the
upper chamber 64 a short distance for a purpose to be described
~- hereinafter. The upper chamber 64 is also formed of a flexible
` material and in addition to being secured with the roof S at
10 is secured on opposite sides of the lower tubular reservoir
62 at 66a and 66b. The flexible material 64 is preferably
formed with a foam floa~tion characteristic in order that the
sheet 64 will float adjacent the sheet S when the pneumatic
support column is in the inoperative condition and the reservoir --
;~ R is full of water. Suitable connections 67 are provided for
communicating with a supply of air to an auxiliar~ blower AB
as illustrated in Fig. 9. With the ends of the chamber closed
pneumatic pressure in the support column X will be greater than
that under the roof S and will tend to provide a support
column at that point on the sheet S. The water ballast in the
- 14 -
"'
, , ., . ~ ~
ir` ~
`' 1(37~39Z5
` 1 lower chamber will of course prevent the lifting of the sheet
S and the pneumatic support column X from the floor 10 of the
.,
.~. reservoir R.
: It will be apparent to those skilled in the art that
other means than those illustrated herein may be used to ballast
' the cover. For instance, the ballast chamber 62 may be attached
,, to the cover by flexible lines or a single sheet of material
.::-. .
~: which will enable the cover to inflate sufficiently to provide
- adequate worker access to the reservoir.
.- 10 As mentioned previously the enclosed ends of the lower
;-: :,
, : ballast chamber protrude slightly beyond the pneumatic support
~:- column chamber 64. This is done to provide access to the
' ballast chamber 62 for controlling the filling of the ballast.
~, When the roof is in the normal operating condition floating
;,j:j
on the liquid reservoir the foam cover 64 will pull the opening
~: in the top of the ballast chamber 62 extending beyond the chamber
~- 64 adjacent the sheet S. A zippered opening or access port
., . .:
~ in the sheet S is provided adjacent this fill point and when
.i it is desired to maintain the reservoir using the pneumatic
column X these access ports to be closed to contain the water
... normally present therein when the reservoir R is drained of the
liquid L. When the sheet S is in the floating condition these
ports are left open and the water is left free to flow in and
-~ out of the ballast chamber 62.
To prevent an undesired accumulation of rain water
and the like on the upper side of the cover apparatus A one or
more drain sumps DS may be provided as illustrated in 51. The
drain sumps DS provide a gathering sp.ot for the rainwater
as well as providing for the elimination of the rainwater from
the top of the cover where it could possibly contaminate the
~:~......... liquid L in the reservoir R.
- - 15 -
: .
`` 10799Z5
~;
1 The drain sump DS as best illustrated in Fig. 10 is
provided with sides 72 and 74 made of impervious flexible material.
; The bottom or floor 76 of the drain sump DS is also made of
impervious material and is preferably ballasted to hold the
. j
, bottom 76 in a position below the sheet S in order that the water
will drain into the pocket 78 formed by the drain sump DS.
-~ To remove the rainwater from the pocket 78 of the
drain sump DS a pump 80 may be positioned in the pocket 78 to
~` remove the water preferably a submersible type electrically
`~ 10 driven pump is used with electrical connection 82 being connected
to a source of electrical power. Also, jet pumps or aductors
may be employed as illustrated in Fig. 1.
. ,~ ,
In Fig. 1 a source of fluid under pressure is provided
such as by pump 84 is separated into two flowlines 86a and 86b.
As illustrated in Fig. 11 the conduit 86a extends out-
wardly on the cover S until it reaches drain sump DS. An
aductor or jet pump is connected into conduit 86a in the drain
~j ..
' sump DS. The aductor 88 discharge may then be run to the edge
of the reservoir to a discharge location or it may be run to
another drain sump as illustrated in Fig. 1. The aductor 88
is provided with a suitable backflow valve 90 in the conduit
86a and a foot valve 92 on the inlet of the aductor 88 for the
fluid to be evacuated from the drain sump DS. Such arrangement
of using a jet pump is old and well known to those skilled in
the art.
The foregoing disclosure and description of the
-- invention are illustrative and explanato~y thereof, and various
changes in the size, shape and materials as well as in the details
` of the illustrated construction may be made without departing
from the spirit of the invention.
'
- 16 -
"~
:'
