U.S. patent application number 11/344391 was filed with the patent office on 2007-08-02 for trench pan and grate assembly.
This patent application is currently assigned to TUF-TITE, INC.. Invention is credited to Theodore W. Meyers.
Application Number | 20070177942 11/344391 |
Document ID | / |
Family ID | 38322245 |
Filed Date | 2007-08-02 |
United States Patent
Application |
20070177942 |
Kind Code |
A1 |
Meyers; Theodore W. |
August 2, 2007 |
Trench pan and grate assembly
Abstract
A trench pan and grate assembly generally rectangular in shape,
having downwardly ramped transition bottom walls and an
integrally-formed but removable strainer plate, terminating in a
round pipe receiving fitting that is, through use of a bushing,
able to accommodate the common different types of
commercially-available plastic plumbing pipe of a given nominal
size, and thus be connected to an underlying sloped main drainage
pipe. The separate grate member is installed and fastened down, via
threaded fasteners, to the trench pan to complete the assembly.
This heavy duty grate is formed using gas-assist molding procedures
with fractional-melt material (melt number<1.0). Individual
assemblies can be formed end-to-end into an elongate trench drain
system, with each assembly containing no standing effluent, and
connected to different drainage pipes if desired. Assemblies can be
solvent welded to drainage piping and thus require nothing to
position and hold while the adjacent concrete is being cast.
Inventors: |
Meyers; Theodore W.;
(Barrington, IL) |
Correspondence
Address: |
MARSHALL, GERSTEIN & BORUN LLP
233 S. WACKER DRIVE, SUITE 6300
SEARS TOWER
CHICAGO
IL
60606
US
|
Assignee: |
TUF-TITE, INC.
Lake Zurich
IL
60047
|
Family ID: |
38322245 |
Appl. No.: |
11/344391 |
Filed: |
January 31, 2006 |
Current U.S.
Class: |
405/40 |
Current CPC
Class: |
E03F 3/046 20130101;
E03F 5/0408 20130101; E03F 5/0407 20130101 |
Class at
Publication: |
405/040 |
International
Class: |
E02B 13/00 20060101
E02B013/00 |
Claims
1. A high strength injection-molded plastic grate for use with
onsite waste and drainage system components, comprising: a
generally planar drain member having a plurality of through
openings for permitting drainage of fluids therethrough; a
plurality of transverse cross walls connected to the drain member
and extending generally downwardly therefrom; at least one of the
transverse cross walls formed to have a molding gas-assist-created
void substantially at the interface of that at least one transverse
cross wall and the drain member; a plurality of longitudinal walls
connected to the drain member and to the respective transverse
cross walls, and extending downwardly from the drain member; and
the grate being formed of fractional melt injection molding
material.
2. The grate of claim 1, and wherein at least one of the
longitudinal walls is formed to have a molding gas-assist-created
void at the interface of that at least one longitudinal wall and
the drain member.
3. The grate of claim 1, wherein the fractional melt material
comprises HDPE material having a fractional melt between
approximately 0.4 and 1.0.
4. The grate of claim 1, and wherein all of the transverse cross
walls are formed with a molding gas-assist-created void.
5. The grate of claim 1, wherein the gas-assist-created void of the
at least one of the longitudinal walls is of a greater
cross-sectional size than the gas-assist-created void of the at
least one of the transverse cross walls.
6. The grate of claim 1, and a peripheral edge wall extending
downwardly from substantially the perimeter of the planar drain
member, and wherein the outer ends of the respective transverse
cross walls and longitudinal walls are integrally connected to the
edge wall.
7. The grate of claim 6, and a plurality of generally vertically
extending, threaded fastener receiving bosses formed along the
peripheral edge wall.
8. The grate of claim 1, wherein each of the plurality of through
openings is generally of a square shape and not greater than
approximately 1/2 inch by 1/2 inch.
9. The grate of claim 1, wherein on an underside of the grate, each
of the plurality of through openings is isolated by a portion of at
least one of the longitudinal walls and a portion of at least one
of the transverse walls.
10. A trench drain component, comprising: an elongate trench pan
member having a generally upright peripheral wall, a series of
ramped lower walls extending generally downward from the peripheral
wall and terminating in a pipe receiving fitting, wherein the
length-to-width ratio for the elongate trench pan member is greater
than 1:1.
11. The trench drain component of claim 10, and an injection-molded
grate member adapted to be received by the trench pan member, the
grate member being formed of fractional melt molding material and
having gas-assist cavities.
12. The trench drain component of claim 11, wherein the grate is at
least approximately 6 inches wide.
13. The trench drain component of claim 10, wherein the
length-to-width ratio is at least 2:1.
14. The trench drain component of claim 10, and an adapter fitting
operable to be received by the pipe receiving fitting so as to
permit connection of at least one given size commonly-available
plastic drain pipe segment.
15. The trench drain component of claim 14, wherein the plastic
drain pipe segment has a nominal diameter of 4 inches.
16. The method of forming injection-molded plastic grate components
to exhibit substantial impact strength and substantial dimensional
stability, comprising the steps of: using an injection mold for
forming a grate member having gas-assist internal cavities; using a
fractional melt molding material in the mold; and using injection
molding pressures less than approximately 22,000 psi.
17. The method of claim 16, and the step of forming the grate to
measure at least approximately 6 inches in nominal width.
18. The method of claim 16, and the step of forming the grate to
have a length-to-width ratio of greater than 1:1.
19. The method of claim 16, and selecting the fractional melt
material to be fractional melt high density polyethylene
material.
20. The method of claim 19, and wherein the fractional melt is
between approximately 0.4 and 1.0.
21. A trench drain component for use individually or in series,
comprising: a trench pan member having a generally upright
peripheral wall, a lower pipe receiving opening, and a bottom drain
floor formed of ramped drainage walls connecting the peripheral
wall to the lower pipe receiving fitting, and the trench pan member
further adapted to permit at least two trench pan members to be
substantially abutted together, and each separately connected by
the lower pipe receiving opening to an underlying drainage pipe,
when desired.
22. The trench drain component of claim 21, and a grate member
adapted to be received by the trench pan member.
23. The trench drain component of claim 21, wherein the peripheral
wall includes: an upper wall portion adapted to surround the grate
member; an intermediate ledge extending inwardly from, and
generally perpendicularly to, the upper wall portion; and a lower
wall portion extending downwardly from the intermediate ledge, said
lower wall portion disposed inwardly of the upper wall portion, and
the bottom drain floor connected to the peripheral wall at a bottom
end of the lower wall portion.
24. The trench drain component of claim 23, wherein the
intermediate ledge and the lower wall portion define a notch area
along an exterior of the trench pan member.
25. The trench drain component of claim 23, further comprising a
plurality of upstanding teeth disposed on the intermediate ledge,
each of the upstanding teeth being spaced inwardly from the upper
wall at least a distance equal to a thickness of an outer perimeter
wall of the grate member, said teeth and said upper wall
frictionally securing the outer perimeter wall therebetween,
whereby the grate member is releasably retained by the trench pan
member.
26. A trench component for use in a trench drain system,
comprising: an elongated pan member having an upstanding peripheral
wall, a pipe receiving fitting for connection to commonly-available
plastic drain pipe, a generally ramped bottom wall extending from
the peripheral wall to the pipe receiving fitting, and wherein the
length-to-width ratio for the pan member is greater than 1:1.
27. The trench component of claim 26, and a strainer member formed
substantially across one end of the pipe receiving fitting.
28. The trench component of claim 27, wherein said strainer member
is removably connected across said one end of the pipe receiving
fitting by a plurality of reduced thickness connection segments,
said reduced thickness connection segments being breakable to
facilitate removal of the strainer member from the end of the pipe
fitting.
29. The trench component of claim 26, and a grate member adapted to
mount the trench pan, the grate being formed of fractional melt
injection molding material.
30. The trench component of claim 26, and wherein the grate is
formed to have gas-assist chambers.
Description
FIELD OF THE DISCLOSURE
[0001] This disclosure relates to trench drains, sometimes called
channel drains, and more specifically, to a trench pan and grate
assembly that can be used either as an individual unit, or as one
of a plurality of such assemblies joined together such as in a
series, to create a trench drain system.
BACKGROUND OF THE DISCLOSURE
[0002] Elongate drains, or so-called "trench" drains, are commonly
used where there is need to drain a generally extended flat
surface, such as a section of a building floor, across a garage
door opening, an edge of a parking lot or driveway, and the like.
One type of trench drain is a heavy duty type trench for heavy use
conditions. It is usually formed of a pre-cast polymer concrete
drain unit. This type of trench drain typically has a specific
pitch built into each separate trench unit, such that extensive
engineering specifications are required for the manufacture, layout
and installation of the trench. For example, as many as 20 or more
different pieces, each having its own built-in slope, are required
to create a trench drain run of a given length. Such heavy duty
trench drains are relatively difficult and labor intensive to
assemble on-site. Also, since each trench piece is necessarily
different, such trench drain systems require substantial
manufacturing and mold costs. Further, so that such a system can
readily be installed, each separate trench piece is required to be
warehoused and purchased, thus making such a sloped-type heavy duty
trench drain system extremely costly to make, specify, purchase,
warehouse and install.
[0003] Another type of trench drain is typified in U.S. Pat. No.
5,529,436, as owned by Tuf-Tite, Inc., the assignee of the present
disclosure. That form of trench drain comprises multiple components
including a trench, a grate, and snap-on end caps, but each trench
drain section is the same as the next, i.e., they are
interchangeable. Integral but removable drain components permit the
assembly of multiple size pipes to the bottom of the trench.
Regardless what diameter pipe is chosen to be used, that pipe
connects to an underlying pitched drainage pipe for the trench
drain, as the channel bottom of the trench drain itself is
generally "neutral" (i.e., non-sloped) relative to the flat surface
in which it is cast in place. That is, there is no pitch of any
type provided to the internal bottom surface of the channel forming
the trench drain. While generally easy to install and economical in
use, an occasional objection has been raised to that type of trench
drain, namely that fluids, once entering through the grate member
and collecting in the underlying trench, can stand and not be fully
drained away, i.e. since the floor of the channel making up the
trench is neutral.
[0004] Further yet, there is a so-called trench frame product, with
associated grate, that does not require any type of
specially-formed underlying trench channel structure. Rather, as
normally intended to be installed, a separate frame member is
directly fastened to the top portion of an underlying primary drain
pipe, whereby after the pipe's top segment is removed, i.e. cut
away, that pipe itself becomes, in effect, the channel for the
trench so created. Then, at least one sloped secondary drain pipe
is attached to the primary pipe, i.e., for draining away fluids
collected within the combination trench frame and connected primary
header pipe. Disclosure of that type trench frame and grate product
is set forth in U.S. patent application Ser. No. 11/110,588 filed
Apr. 20, 2005 entitled Trench Drain Frame and Grate Assembly, which
is also owned by the assignee of the present disclosure.
[0005] Notwithstanding these and other various trench drain-type
products, there has remained a need for an elongate trench drain
product that can permit connection to several different versions of
a given plumbing pipe size, that has sufficient built-in slope to
prevent any standing water, and that can be used either separately,
or as part of a plurality of identical units connected into a
series of a desired configuration, to create an extended trench
drain system.
[0006] Previously, the known injection-molded plastic grates used
with trench drains were all formed with polyethylene injection
molding materials having a so-called melt number greater than 1.0,
and normally they were made with HDPE molding material. However, to
the extent known, there have been no trench drain grates formed
with injection molding material having a so-called fractional melt,
i.e. with a melt number less than 1.0. Also, as best known, while
so-called gas-assist injection molding procedures have been
previously used in forming non-grate type of on-site waste and
drainage products, such as risers, riser lids, and riser pans, no
such gas-assist procedures have been successfully used in forming
grates for on-site waste and drainage products. Further, there have
been prior unsuccessful (and as best understood since they have
since ceased) attempts at using gas-assist procedures when
injection-molding of fractional melt materials into unrelated
(non-grate) type products, such as flat air conditioner pads. Thus,
until the present disclosure, there has been no known use of
gas-assist procedures for injection-molding of grates that are
intended for use with drainage and on-site waste products.
[0007] Prior known injection-molded plastic grates, once formed,
suffered from numerous twists and warpage. For example, they always
needed to be fastened down securely to an underlying trench drain
or trench frame component to become relatively flat. That is, such
prior known injection-molded grates were normally not flat, square
and straight enough to be able to be sold and used as separate
grate units alone, i.e. such as to be purchased for use with
separately-formed trenches at a job site. Further, many end users
desire at least a 6'' wide grate, i.e. rather than a 4'' plastic
grate as is commonly sold, such as by the assignee of the present
disclosure, with trench drain and trench frame units. But there is
the risk that such wider grates would not be sufficiently strong to
handle medium-to-heavy vehicle traffic, and might break or deform
with such heavy duty use. Thus, there has remained a need for
plastic grate products that could be formed to be heavy duty and
dimensionally stable.
SUMMARY OF THE DISCLOSURE
[0008] The present disclosure provides a combination trench pan and
grate assembly where the pan is long and narrow, i.e. with a
length-to-width ratio greater than 1:1, and thus, generally
rectangular in shape, and has downwardly-ramped transition bottom
walls terminating in a round pipe receiving fitting that is,
through use of a bushing, able to advantageously accommodate the
common different types of commercially-available plastic plumbing
pipe of a given nominal size. A plurality of individual trench pan
and grate assemblies can be formed end-to-end into an elongate
trench drain system. That is, each assembly can be connected,
through a bottom stub pipe and upwardly-facing sweep tee component,
to an underlying sloped main drainage pipe. Importantly, however,
because the floor of each trench pan is ramped, i.e., downwardly
sloped, rather than being neutral, no water or other fluids are
allowed to stand within each respective trench pan. Instead, as
collected, such fluids are immediately drained out of the trench
pan's bottom to the underlying drain pipe.
[0009] During installation, unlike many prior trench drain
components, no separate mounting equipment is required to position
and hold the trench pan in place, while the concrete is being cast
about it. This is because the trench pan is first fastened in place
in the correct position and height, such as by solvent welding, to
the top of an underlying generally vertical stub pipe section,
which in turn extends upwardly from an appropriate sweep tee (or
sanitary tee) which itself connected to the underlying sloped
drainage pipe. That same underlying sloped drainage pipe can be
connected to yet other selectively-placed trench pans in the same
manner, whereby an entire layout out of separately-positioned
trench pan and grate assemblies can be installed in a given floor
surface or drainage area, or alternatively, a running end-to-end
series of such identified assemblies can be formed.
[0010] An integrally-formed but removable strainer plate covers off
the pipe receiver fitting that extends downwardly from the ramped
bottom walls of the trench pan. The separate grate member is
installed and fastened down, via threaded fasteners, to the trench
pan to complete the assembly. While the present disclosure is not
limited in this regard, the elongate trench pans can be formed, for
example, as short as 12 inches long, or instead as long as 3 feet,
or even longer. Through use of the present trench pan and grate
assembly, the problem of standing water is eliminated. Further, a
secondary drain pipe is not needed. Further yet, there is no need
for any special order, multiple component sloped trench drain
system, i.e. where each component must be specifically and
carefully fastened to adjacent ones of the correct slope and size,
so as to allow the overall slope trench drain to be formed.
[0011] Rather, with the present disclosure, only a single type
trench pan and grate unit, i.e. of one shape and one size, is
needed to make a trench drain, whether installed singly at one
location, installed instead at multiple separate locations, or
installed in an abutting series arrangement.
[0012] Also, the grate used with the present trench pan is
preferably formed of a fractional melt injection-molding material,
and then through use of gas-assist molding procedures, results in a
grate having substantially improved impact strength characteristics
and dimensional stability.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a top perspective view of the trench pan of the
present disclosure, and with the grate removed for better
viewing;
[0014] FIG. 2 is a bottom perspective exploded assembly view of the
trench pan of FIG. 1, with an associated bushing;
[0015] FIG. 3 is a side elevation view of the trench pan of FIG.
1;
[0016] FIG. 4 is an end view of the trench pan of FIG. 1, and with
a corner portion broken away for better viewing of interior
components;
[0017] FIG. 5 is a top plan view of the trench pan of FIG. 1;
[0018] FIG. 6 is a bottom plan view of the trench pan of FIG.
1;
[0019] FIG. 7 depicts in perspective view the trench pan and grate
assembly of the present disclosure, in combination with a sweep
tee, as installed within a drainage piping layout;
[0020] FIG. 8 is a top plan view of the grate of the trench pan of
FIG. 1;
[0021] FIG. 9 is a bottom plan view of the grate of the trench pan
of FIG. 1;
[0022] FIG. 10 is a cross-section of the grate viewed along lines
10-10 of FIG. 9;
[0023] FIG. 12
[0024] FIG. 11 is a cross section, broken away, of the grate as
securely received on the trench pan; and
[0025] FIG. 12 is a top plan view of a plurality of the trench pans
of FIG. 1, arranged in a series.
DETAILED DESCRIPTION OF THE DISCLOSURE
[0026] Having reference to the drawings, wherein like reference
numerals indicate corresponding elements, there is shown in FIGS.
1-6 an illustration of an elongate trench pan and grate assembly,
generally denoted by reference numeral 20. The overall assembly 20
is formed to be used as an individual modular unit, i.e. capable of
being used singly or as part of an interconnected plurality formed
into a running trench system. Assembly 20 comprises a trench pan
22, a grate 24, and when needed, depending on the associated pipe
size, a separate adapter bushing 26 (see FIG. 2). The trench pan 22
is integrally formed as a one-piece elongate trench unit having a
peripheral wall formed of four integral generally
vertically-aligned edge walls, comprising end walls 28a, 28b and
side walls 30a, 30b. The configured bottom drainage wall 32 of the
trench pan 22 preferably comprises four ramped, i.e. downwardly
sloped, bottom wall portions 34a, b, c, d. Preferably, ramped
bottom walls 32a, c have generally flat-angled walls, while ramped
bottom walls 32b, d are generally curved, i.e., formed as
non-linearly sloping walls. The respective ramped bottom walls 34a,
b terminate at their respective lower edges in a flat annular ring
surface 36 having a drain opening 37, across which is formed a
frangible, i.e. removable, strainer plate 38. The strainer plate 38
has a series of drain apertures 40 of varying sizes and is
integrally connected, via reduced thickness areas 42, to the
annular ring surface 36. The drain apertures 40 in the strainer
plate 38 are preferably less than 1/2 inch by 1/2 inch in size, so
as to cause the plate 38 to act as a secondary grate (relative to
grate 24), i.e. to help strain out even smaller sized debris, for
subsequent cleaning and removal, as desired. It will be understood
that, if the end user of assembly 20, once it is installed, does
not wish to have the additional water flow restriction caused by
the extra strainer plate 38, then the same can be removed, i.e., by
breaking it away from ring 36 along the reduced thickness
connections 42.
[0027] Extending downwardly from the sloped bottom wall 32, below
the ring surface 36, is a female hub section acting as a
pipe-receiving fitting 44. In one sample made in accordance with
the present disclosure, the trench pan 22 is formed so that the
pipe fitting 44 was sized to accept 4-inch PVC plumbing pipe, and
particularly so-called Schedule 40 4-inch plastic plumbing pipe.
However, if either one of so-called SDR-35 or ASTM 2729 4-inch
plastic plumbing pipe is desired to be used instead, then the
adapter bushing 26 (see FIG. 2) can be inserted into the interior
of the pipe fitting 44. Then, the associated stub pipe extension 46
(see FIG. 2) is inserted at one end into either the interior of the
pipe fitting 44 or of the bushing 26, depending on which type 4
inch pipe, for example, is being used for the stub pipe 46. Then,
the other end of stub pipe 46 is inserted into an upwardly facing
sanitary or so-called sweep tee member 45, which in turn is
connected to an underlying sloped drainage pipe 47 (see FIG. 7).
Because the trench pan 22, bushing 26, and stub pipe 46 are all
formed of a PVC or an ABS material (i.e. a solvent--weldable
plastic material), they can all preferably be rigidly secured and
sealed together by use of a suitable and commonly-available solvent
weld material (not shown).
[0028] Because of the adapter bushing 26, one trench pan 22 can be
used with any of the multiple different types of commonly-available
plastic plumbing pipe of a given size, i.e. given diameter. Of
course, the diameter of the pipe fitting 44 can be formed to be of
any desired size so as to accommodate a chosen, yet different,
diameter of commonly available plumbing pipes, such as, for
example, formed to accept nominal 3 inch or 6 inch size pipes,
instead of a nominal 4 inch size pipe.
[0029] Further, for the sample that was made in accordance with the
present disclosure, but it will be understood the disclosure is not
limited in this regard, the overall width of the trench pan was
chosen to be approximately 6 inches, and the overall length was
approximately 12 inches. However, it will be readily understood
that, while still preferably using an approximately 6 inch width
(or even greater width if needed), the overall length of the
elongate trench pan 22 could be formed to be, for example,
approximately 3 feet, i.e., so as to be of maximum length to take
best advantage of commercially available shipping cost
efficiencies. Further, whether formed of a shorter, e.g., a 12 inch
length, or a longer, e.g., a 36 inch length, the overall height of
the trench pan 22 would preferably remain approximately 4-1/4 inch.
In any case, regardless of the overall length chosen for the trench
pan 22, the bottom wall 32 would continue to have sufficient slope,
i.e., a slight draft angle towards the middle, so as to properly
collect and drain away fluids via the ramped bottom walls
34a-34d.
[0030] Turning to FIGS. 1-6, it will be seen that the configuration
of the lower edges of the walls 28a, b and 30a, b create a notch
area, generally designated by reference numeral 48. That is, notch
area 48 is formed by a generally horizontally-extending ledge
portion 50 and a vertical wall portion 52. Formed in the vertical
wall 52, along the longitudinal edges of the trench pan 22, are a
series of bosses 54 each having a fastener aperture 56 for
receiving a threaded fastener 58 (see FIG. 7). Further, extending
upwardly from horizontal ledge wall 50, and spaced inwardly from
the respective sidewalls 38, 30b (by a separation distance "D"--see
FIGS. 4 and 11), are a series of upstanding posts or teeth 60, each
of which has a rounded inner upper corner 62. The thickness of the
respective longitudinal side walls 84a, 84b of the grates'
peripheral wall 80 (discussed later herein) are able, when grate 24
is frictionally-fitted onto the trench pan 22, to fill the gap of
separation distance D, i.e. between teeth 60 and ledge wall 50 (see
FIG. 11).
[0031] Turning now to FIGS. 8-10, there is shown the grate 24 as
having an upper grate wall 74 formed with a matrix of drainage
openings 76, downwardly-extending bosses 77 containing fastener
apertures 78 (to receive the threaded fasteners 58 see FIG. 7), and
a downwardly-extending peripheral wall 80 formed of end walls 82a,
82b, and side walls 84a, 84b. (Preferably, the drainage openings 76
are formed so as to be compliant with, for example, the ADA
(American With Disabilities Act), and more preferably, are formed
to be rectangular and are approximately 1/2 inch by 1/2 inch in
size.) Extending downwardly from the grate wall 74 and formed
transversely between grate sidewalls 84a, 84b are a series of
transverse cross walls 86. Also, as formed longitudinally between
grate end walls 82a, 82b, and interjoined with transverse cross
walls 86, are a series of longitudinal walls 88. As seen in FIG. 9,
where the respective transverse longitudinal walls 86 and 88 merge,
an enlarged post-like area 90 is created. Further, as seen in FIGS.
9 and 10, where the upper reaches of many of the transverse cross
walls 86, and at least one of the longitudinal walls 88, merge into
the lower surface of upper grate wall 74, these walls, in effect,
flare out to form an enlarged generally V-shaped channel area 92.
In one sample made in accordance with the disclosure, only the
central longitudinal wall 88 had such a flared area 92, whereas
each of the respective transverse cross walls 86 were formed to
include such a flared area 92. However, any or all of the
longitudinal cross walks 88 could be so formed, i.e., flared.
Further, preferably, the cross sectional size of the flared area 92
of the central longitudinal wall 88 is greater than that of the
flared areas 92 of the transverse cross walls 86.
[0032] More specifically, such flared areas 92 are formed so as to
be internally hollow (see FIG. 10). This is the result of using
gas-assist molding procedures during the manufacture of the grate
24. That is, pressurized gas is introduced into the mold cavity
when the hot molten plastic molding material is simultaneously
being injected under pressure into the mold (not shown). The
primary effect of introduction of such pressurized gas during the
gas-assist molding procedure, in essence, is to help force the
molten plastic injection molding material into and on through the
various internal cavities in the pattern of the mold (not shown) in
which the grate 24 is formed, and then on against the mold's walls.
When formed using such a gas-assist procedure, the overall
strength, and primarily the weight-bearing capacity, of grate 24 is
significantly improved. For example, in comparison to a narrower
4-inch wide grate, but otherwise similarly designed grate, but as
made without use of any gas-assist procedures, the present grate 22
is believed to have at least a 40% increase in weight-bearing
capacity. Furthermore, by using such a gas-assist procedure, it has
been found that previously unusable, but otherwise desirable,
injection molding materials can now actually be used to form the
grate 24 for use with trench drain components. These include
molding materials having so-called fractional melts (i.e., a melt
number less than 1.0). Preferably, the gas-assist formed grate of
the present disclosure is formed of a fractional melt material
having a melt number between approximately 0.4 and 1.0. For
example, in one sample made in accordance with the present
disclosure, a fractional melt molding material comprising
fractional melt, high density polyethylene and having a melt number
of 0.5 was used.
[0033] Advantageously, with the present disclosure, where
gas-assist is used, such fractional melt materials can now be
satisfactorily used in injection molding plastic grate parts.
Normally, such fractional melt materials could not be used for
forming a grate, as they are so thick and sluggish in use as to not
move to completely fill in all the various mold cavities, except
perhaps through use of very significantly increased mold injection
pressures (i.e. such as in the elevated range of between 25,000 and
27,000 psi), but that requires significantly more costly molding
equipment, and has its own problems. Instead, only
normally-required injection pressures, i.e. in the normal range of
approximately 20,000 to 22,000 psi, need be used now when forming
the gas-assist-created grate of the present disclosure. This is a
significant advantage, and provides cost savings.
[0034] In any event, the use of such low melt molding materials
results in a grate 22 having superior strength and superior
dimensional stability properties, as compared to the prior known
grates as formed of high melt molding materials. For example, the
high strength grate 22 made in accordance with the present
disclosure, i.e. as formed of fractional melt material, using
gas-assist molding procedures, would likely at least double the
impact resistance for the grate, as compared to a similarly sized
grate part, but as made using an injection molding HPDE material
that instead had a melt index greater than 5.0.
[0035] Further, the known prior art grates for trench drains were
made without gas-assist procedures and with a greater-than-1.0 melt
HDPE material, with the results that those grates were often formed
as curled or otherwise out-of-alignment, except when they were
screwed down within a trench drain or trench frame. However,
advantageously, the grate 24 as made in accordance with the present
disclosure (i.e., via gas-assist procedures using fractional melt
material) now remains substantially dimensionally stable and of
increased impact strength. That is, the presently-disclosed grates
remain generally straight, flat and square-cornered, as believed to
be within +/-1%. This is a significant improvement over prior art
injection-molded grates, since the prior grates were not
sufficiently dimensionally stable as to be separately useable in
angle iron rail-type trench drains, i.e., trench drains as formed
up from angle iron rails encased in and above a concrete trench. In
contrast, the dimensionally-stable grates of the present disclosure
will lie substantially flat (i.e. they do not curl up or have
out-of square corners), such that they can be readily used in such
alternate-type trench drain systems.
[0036] Instead of using an injection-molded plastic grate, a grate
suitably-sized and formed of cast iron or other metal could be used
with trench pan 22. Thus, it will be understood that the presently
disclosed trench pan is not limited to use only with
injection-molded plastic grates.
[0037] As seen in FIG. 12, the trench pan and grate assembly of the
present disclosure can be easily and cost-effectively used in an
elongated end-to-end series, in lieu of a long run of heavy duty
individually pre-sloped trench drain components of the prior art.
Also, advantageously, there is no need for extra mounting and
holding components, i.e., reinforcement bar supporting members, to
maintain the position of the individual trench pans during the
concrete casting installation: process. Further, when a plurality
of trench pan and grate assemblies are laid out in an end-to-end
arrangement, they need not be drained so as to flow in only one
direction, via a single underlying sloped drainage pipe. Instead,
one half (or less, or more as desired) of the given number of such
end-to-end assemblies can be drained in a second direction via a
second sloped drainage pipe. When laid out in an end-to-end series,
there is no flow occurring trench pan-to-trench pan, unlike with
prior trench drains of the present assignee. Rather, each trench
pan is a fully draining unit unto itself.
[0038] Thus, with the trench drain and grate assembly of the
present disclosure, the end user gets all of the advantages (i.e.
sloped floor to prevent standing fluids) of prior expensive
pre-sloped trench drain products, but without the cost, and which
all can be accomplished with only one cost-effective part to make,
store, purchase, warehouse, and also which can be used as a single
location trench drain, or in an end-to-end running series of such
trench drain and grate assemblies.
[0039] Finally, by using gas-assist molding procedures, for the
first time an injection-molded grate for use with on-site waste and
drainage component can be formed of fractional melt materials that
provide substantial impact strength and substantial dimensional
stability, and without the need for use of extra high cost molding
equipment having extraordinarily high injection molding pressures.
Also, for the first time, the present disclosure allows the
resulting gas-assist, fractional melt, injection-molded grates to
be sold and used as separate items, due to their resulting flatness
and other dimensional stability.
[0040] While certain preferred embodiments have been disclosed
herein, it will be appreciated that variations may be made thereto
without departing from the scope of the appended claims.
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