Cover for backflow prevention device

A protective enclosure for a backflow prevention device including a rectangular cover member having insulated top and side walls secured to a platform member to completely enclose the backflow prevention device. One of the side walls is provided with a drain opening adjacent the platform member and a closure member hinged above the drain opening and biased to a closed position. In large cover members, the side walls are sub-divided into removable side panels to facilitate access to the interior space within the cover member and also to facilitate assembly and disassembly.

BACKGROUND OF THE INVENTION 
This invention relates to a protective enclosure for a backflow prevention 
device, and more particularly to a prefabricated insulated, protective 
enclosure for a backflow prevention device. 
A backflow prevention device is an assembly of one or more check valves 
incorporated in a liquid supply line to prevent the backflow of any of the 
liquid, and particularly contaminated liquid, into the original 
uncontaminated supply line. Since these backflow prevention devices are 
usually installed in a water supply line outdoors and above ground, it is 
important that the devices be enclosed and protected from the weather, and 
particularly from freezing. 
Heretofore, large concrete or cast iron boxes have been constructed around 
the backflow prevention device. A cover member or door is provided in the 
top of the box to provide the only access into the interior of the box for 
servicing the device. Open drain holes are formed in the lower portions of 
the side or end walls of the box to drain any water collecting within the 
box away from the box. Occasionally loose insulation material is placed 
within the box in an attempt to insulate the backflow prevention device. 
Because of the size of the backflow prevention devices and the boxes, the 
top cover or door renders access within the interior of the box difficult. 
Furthermore, because of the open fixed drain holes in the concrete or iron 
boxes, it is just as easy for water or other foreign objects to move from 
the outside through the drain holes into the interior of the box as it is 
for water to discharge through the drain holes. Furthermore, cold air can 
easily pass into the interior of the box through the drain holes, which 
can hasten the freezing of the water within the pipes and valves of the 
backflow prevention device. 
Another cover device for partially enclosing a backflow prevention device 
is disclosed in the Devine U.S. Pat. No. 4,726,394 issued Feb. 23, 1988, 
for "HEATED COVER FOR PIPELINE BACKFLOW PREVENTER COMPONENT ASSEMBLY". 
This cover member includes several side sections including segments of the 
top wall adapted to be joined along certain longitudinal and transverse 
lines and clamped together on opposite sides of the backflow prevention 
device. The Devine cover member includes openings 44 in the top portion of 
the cover member to permit the valve stems 24 to project upward above the 
top of the cover member. The valve stems 24 support hand wheels 25 located 
above and on the outside of the cover member to facilitate controlling the 
valves from the outside of the cover member. The walls of the Devine cover 
member are insulated, and a drain opening 40 is provided in the end walls 
to permit drainage of liquid from the space within the cover member to the 
outside. The drain openings 40 are covered by flexible flaps 42 which will 
flex outwardly to permit to flow outwardly. 
In spite of the coverage provided by the Devine cover member, nevertheless, 
the stem openings 44 provide passages for air into the cover chamber, and 
the stems 24 function as heat conducters permitting heat loss from the 
backflow prevention device to the outside of the cover member. 
SUMMARY OF THE INVENTION 
It is therefore an object of this invention to provide a pre-fabricated 
protective enclosure for a backflow prevention device in which the 
pre-fabricated walls are thermally insulated and the interior of the 
enclosed space is readily accessible at a lower elevation than the top of 
the enclosure. 
It is a further object of this invention to provide a protective enclosure 
for a backflow prevention device having a drain opening which is 
automatically covered or closed when water is not draining through the 
drain opening. 
It is a further object of this invention to provide a pre-fabricated 
protective enclosure for a backflow prevention device in which the walls 
are not only insulated, but are also lightweight to facilitate handling, 
and assembly and disassembly of the enclosure relative to the backflow 
prevention device. 
Another object of this invention is to provide a protective cover which 
will completely enclose a backflow prevention device to minimize danger of 
frozen pipes and valves within the device. 
A further object of this invention is to provide in a protective enclosure 
for a relatively large backflow prevention device a plurality of removable 
side walls to facilitate access to the enclosure space through the sides 
of the cover member and also to facilitate assembly, disassembly storage 
and transportation of the parts of the enclosure

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the drawings in more detail, FIGS. 1-7 disclose the 
preferred embodiment of a protective enclosure 10, of a large size, for a 
backflow prevention device 11 (FIG. 1). The backflow prevention device 11 
disclosed in FIG. 1 includes a pair of check valves enclosed within the 
check valve housings 12 and 13, a relief valve enclosed within the relief 
valve housing 14, a pair of cut-off valves and handles or hand wheels 15 
and 16, and an inlet pipe 17, and an outlet pipe 18 continuing into the 
ground G. 
The protective enclosure 10 basically includes a cover member 20, a 
rectangular base frame 21 and a platform member 22. The platform member 22 
may be pre-fabricated, or it may be poured in situ upon the ground G so 
that its top floor surface 23 is planar and level. If poured in situ, the 
platform member may be made of concrete and poured around the inlet pipe 
17 and the outlet pipe 18 to form the inlet and outlet pipe holes or 
openings 25 and 26. 
The cover member 20 disclosed in FIGS. 1-7 includes a pair of end panels 29 
and 30. The cover member 20 also includes a pair of opposed side walls 
including a pair of removable side panels 33 and 34 and 35 and 36 on 
opposite sides of the cover member 20 and a pair of access panels 37 and 
38, which when assembled are in coplanar relationship on the opposite 
sides of the cover member 20. The cover member 20 further includes a 
removable rectangular top wall or top wall member 40. The height of each 
of the end panels 29-30, the side panels 33-36 and the access panels 37-38 
is greater than the height of the device 11 and particularly the height of 
the cut-off valve handles 15-16. 
The rectangular base frame 21 is large enough to fit around the backflow 
prevention device 11, as disclosed in FIG. 1. Moreover the rectangular 
base frame 21 is formed from elongated side angle members 41 and 42 and 
end angle members 43 and 44. The angle shape of each of the side and end 
members 41-44 includes a bottom horizontal flange 45 and an outer vertical 
flange 46. The horizontal bottom flanges 45 of each of the angle pieces 
41-44 are secured to the top surface 23 of the platform member 22 by 
appropriate concrete fasteners, such as the bolts 47. 
Each of the removable side panels 33, 34, 35, and 36 is constructed of a 
sheet metal envelope including a telescoping outer metal skin member 49 
and an inner metal skin member 50 encapsulating a wooden frame work, such 
as the upper and lower transverse redwood frame members 51 and 52 (FIG. 5) 
and end frame member or post 53 (FIG. 4), and a relatively thick 
insulating layer 54. The insulating layer 54 may be made of insulation 
material, such as polyisocyanurate, having a substantially high R-value, 
such as an R-value of 8.4. Each of the removable side panels 33, 34, 35, 
and 36 is rectangular with substantially square edges. 
Each of the end panels 29 and 30 is also rectangular to define the entire 
end walls of the cover member 20. Each end panel 29 and 30 is also 
provided with vertical end channels 31 for receiving the corresponding end 
portions of the side panels 33, 34, 35, and 36. Each of the end panels 29 
and 30 have substantially the same construction as the side panels 33-36, 
including the outer metal cladding composed of telescoping outer and inner 
metal skins 55 and 56 encapsulating thick insulating material 53, as 
illustrated in FIG. 7. No wooden framework is normally included in the end 
panels 29 and 30. 
The access panels 37 and 38 are of substantially the same construction as 
the side panels 33-36, except no wooden frame members are necessary. Each 
access panel includes the same metal cladding 61 and 62 encapsulating the 
insulation layer 53, as illustrated in FIG. 6. 
One of the access panels, such as the panel 37, is provided with a 
transverse drain opening 63 in its bottom end portion covered by a hinged 
closure member or flap 64. The closure member 64 is supported by a 
transverse hinge member 65 secured to the outer surface of the lower 
portion of the metal skin 61 and to the upper surface of the drain flap 64 
in such a manner that the closure member or flap 64 may swing between its 
closed position disclosed in solid lines in FIG. 6 in coplanar vertical 
relationship with the access panel 37 and an outer open position disclosed 
in phantom in FIG. 6. 
The drain flap or closure member 64 is also preferably constructed of the 
same metal cladding or sheathing as the cladding 61 and 62, encapsulating 
a thick layer of the insulating material 53. 
As best disclosed in FIG. 2, a plurality of drain ports or apertures 66 are 
formed in the vertical flange member 46 of the side angle member 42. Some 
of these drain opening 66 may take the form of notches 67 cut all the way 
downward to the horizontal angle flanges 45, so that any water trapped 
within the rectangular frame 21 is free to flow through the notches 67 and 
the ports 66 when the drain flap 64 is in its open, phantom-line position 
disclosed in FIG. 6. 
Furthermore, after the interior of the frame member 21 has been 
satisfactorily drained, the drain flap 64 is released and returned to its 
vertical, closed position by a biasing action of the return coil spring 
68, illustrated in FIG. 6. 
The outer metal skin 61 of both access panels 37 and 38 project laterally 
from the vertical edges of the access panels 37 and 38 to form outer 
vertical lips or ledges 70 for abutting flush against the corresponding 
outer vertical edge surfaces of the adjacent side panels 33-36. 
All of the end panels 29 and 30, the side panels 33-36, and the access 
panels 37 and 38 are of equal height, and the lower edge portions are 
adapted to be secured against the vertical flanges 46 of the angle frame 
21 by appropriate fasteners, such as the bolts or screws 71, (FIGS. 5 and 
7). 
Mounted upon the top edge of each of the end panels 29 and 30, the side 
panels 33-36, and the access panels 37 and 38 is an elongated continuous 
unequal leg channel 72, as illustrated in FIG. 5. The unequal leg channel 
72 includes an elongated horizontal web 73. Depending from the outside 
edge of each web 73 is a front depending flange 74. From the rear edge of 
each web 73 is a rear flange 75 projecting farther downward than the front 
flange 74. The depending rear or inside flange 75 is secured to the inside 
surface of each of the side and end walls by an elongated sheet metal 
screw or other appropriate fastener 76 so that the web 73 is spaced above 
the top edge of each corresponding end or side wall to provide the space 
77. 
The top wall 40 is constructed in a similar manner to the end and side 
walls in that the top wall 40 has a solid horizontal top metal cladding or 
skin 79 and a parallel bottom cladding or skin 80 encapsulating a 
relatively thick layer of thermal insulation material 53. Also formed in 
the perimeter of the bottom of the top wall 40 is a rectangular 
channel-shaped recess or groove 82 which is adapted to seat upon the 
unequal leg channels 72, as illustrated in FIG. 5. 
If desired, the top wall 40 may include reinforcing transverse redwood 
beams 83 illustrated by hidden lines in FIG. 2. 
Because of the spacing between the web 73 of the unequal leg channel 72 and 
the top edge of each of the corresponding outside panels 33-36, any of the 
side panels 33-36 is readily removable by simply unfastening the threaded 
fastener members 76 and 71 secured to the side panel 33-36. After the 
fasteners are removed, the particular side panel, such as the side panel 
33, which is desired to be removed, is elevated to occupy the space 77 
above the top edge of the side panel 33 and then the bottom edge may be 
pulled outwardly to separate the side panel 33 from the cover member 20, 
without binding the bottom edge of the side panel 33 upon the floor 23 of 
the concrete platform member 22. 
As illustrated in FIG. 2, the cover member 20 may be easily positioned on 
the end panels 29-30, side panels 33-36, and access panels 37-38. 
After the platform member 22 has been formed about the backflow prevention 
device 11, the rectangular frame 21 is assembled by securing each of the 
elongated angle members 41-44 to the platform member 22 by the anchor 
bolts 47, so that the angle members 41-44 occupy the rectangular shape 
disclosed in the drawings. 
Next, the end panels 29 and 30 are placed in an upright, vertical position 
adjacent the outsides of the end angle members 43 and 44 and secured to 
the vertical flanges 46 of the end angle members 43 and 44 by the 
appropriate number of fastener members 71. 
Then, the side panels 33-36 are fitted against the outsides of the vertical 
flanges 46 of the corresponding side angle members 41 and 42 and within 
the corresponding end channels 31 in the end panels 29 and 30, and secured 
to the vertical flanges 46 by the fastener members 71. 
Then, the access panels 37 and 38 are fitted into the openings left between 
the opposed sets of side panels 33-34 and 35-36 until the lips 70 lie 
flush against the corresponding outside edge portions of the side panels 
33-36, and secured to the opposed panels by the sheet metal screws 84, as 
disclosed in FIG. 3. 
The top wall or panel 40 is then lowered into position so that its downward 
opening elongated recesses 82 are seated upon the horizontal web 73 of the 
unequal leg channel 72. 
The cover member 20 then completely encapsulates the backflow prevention 
device 11 to protect it against freezing, other elements of the weather, 
and dirt and debris. Moreover, the cover member 20 conceals the backflow 
prevention device 11 from view, for aesthetic reasons and also to 
discourage against tampering. 
FIGS. 8-12 disclose a modified cover member 90 adapted to completely 
conceal a backflow prevention device 11, as illustrated in FIG. 8. The 
cover member 90 includes integral end walls 91 and 92 and side walls 93 
and 94 and a top wall 95, with an open bottom. The height of the end walls 
91-92 and the side walls 93-94 is greater than the overall height of the 
backflow prevention device 11. Each of the walls 91-95 is made from 
similar type outer and inner metal cladding or skins 96 and 97 similar to 
those disclosed in the cover member 20 and encapsulating only 
corresponding layers of thermal insulation material 98 of high R-values. 
As disclosed in FIG. 10, the corners of the various panels 91-95 may be 
joined together by a conventional "Pittsburg lock" 99, if desired. 
The side wall 93 of the cover member 90 is provided in its lower edge 
portion with a drain opening 100 covered by the hinged drain flap 101, as 
best disclosed in FIG. 12. In a manner similar to the mounting of the 
drain flap 64, the drain flap 101 is pivotally connected to a portion of 
the side wall 93 above the drain opening 100 by a transverse hinge member 
102. Moreover, the drain flap 101 is biased toward its closed position, as 
disclosed in FIG. 12, by an elongated coil spring 103. 
The cover member 90 is secured around the backflow prevention device 11 
upon the same concrete foundation or platform member 22, as disclosed in 
FIGS. 1-7, by a rectangular frame 105 also made up of elongated angle 
members 106, 107, 108, and 109. However, each of the angle members 106, 
107, 108, and 109 has its bottom horizontal flange 110 projecting 
laterally outward from its vertical flange 111. 
The horizontal flanges 110 are secured to the concrete platform member 11 
by anchor hooks 112, which are preferably pre-welded to the bottom 
surfaces of the horizontal flanges 110 and imbedded in the concrete 
platform member 22 before the concrete is poured or before it has set. 
The elongated side angle member 108 is provided with drain openings or 
apertures or ports 113 formed through the lower portion of the vertical 
flange 111 in the side angle member 108 in registry with the drain opening 
100 in the side wall 93. The drain ports may also include a drain notch 
114, as disclosed in FIGS. 9 and 12, cut entirely down to the surface of 
the corresponding horizontal flange 110 to facilitate drainage. 
The cover member 90 is of a substantially smaller size than the cover 
member 20, and therefore, may be integrally formed, as shown, to 
facilitate handling, assembly, and disassembly. 
When the angle frame 105 is provided with the anchor members 112, then a 
platform member 22 must be formed around the anchor members 112 after the 
rectangular frame 105 has been positioned around the backflow prevention 
device 11. After the frame 105 is installed and the concrete of the 
platform member 22 has set, the sole remaining step for enclosing the 
backflow prevention device 11 is to position the cover member 90 as a unit 
over the top of the device 11 and to seat the bottom edges of the end and 
side walls 91-94 upon the horizontal flanges 110 of the frame 105. The 
bottom edge portions of one or more of the end and side walls 91-94 may be 
secured to the vertical flanges 111 of the rectangular frame 105 by 
appropriate fasteners, such as sheet metal screws or bolts 115. As 
illustrated in FIGS. 9 and 10, the fastener bolts 115 are inserted 
inwardly through the lower portions of the end walls 91 and 92 into 
corresponding holes 116 in the end angle members 106 and 107. 
When it is desired to drain the interior of the space within either of the 
cover members 20 or 90, it is only necessary for the operator to pivot 
outwardly the corresponding drain flap 64 or 101 against the resistance of 
the corresponding spring 68 or 103 and hold the flap 64 or 101 in its 
outward open position, as illustrated by the phantom position of the flap 
64 in FIG. 6, until all the water has been drained from the interior of 
the respective housings. Moreover, the weight and pressure of the water 
within the housing may be sufficient to force the flap 64 or 101 open 
against the action of the corresponding spring 68 or 103 to effect 
adequate drainage. 
After the draining has been completed, the flaps 64 and 101 are released 
and the respective springs 68 and 103 restore the corresponding closure 
members or flaps to their respective closed positions as disclosed in 
solid lines in FIGS. 6 and 12 respectively. 
Access to the interior of the cover member 20 may be obtained in a variety 
of ways, in order to inspect or service the backflow prevention device 11. 
In the cover member 20, the top wall 40 may be raised and removed. 
However, the interior of the space around the backflow prevention device 
11 is more accessible by removing either of the access panels 37 and 38 or 
one or more of the side panels 33-36 as the removal of these panels has 
been previously discussed. The access panels 37 and 38 may be removed 
merely by removing the connecting sheet metal screws 84. 
The side panels 33 and 34 may be removed by first removing the access 
panels 37 and 38 by removing the screws 84, and then removing the bottom 
screws 71 and 76. Then the desired side panel, such as 33, is then raised 
and pulled outwardly to completely separate the side panel 33 from the 
cover member 20. 
In order obtain access to the interior of the cover member 90 it is only 
necessary to unscrew the end fasteners 115 from the rectangular frame 105 
and raise and remove the entire cover member 90 to obtain full access to 
the backflow prevention device 11. 
However, when the cover members 20 and 90 are fully installed upon the 
platform members 22, the backflow prevention device 11 is entirely and 
completely enclosed by solid insulated walls without any openings which 
can be penetrated by cold air or any other weather elements.