# Patent

## Title
Elevator trench drain

## Abstract

An elevator trench drain includes a trench and a drain passageway. The trench has a base wall with peripheral side walls extending upwardly therefrom to define a trench volume therein. The drain passageway extends downwardly from the base wall of the trench and places the trench volume in fluid communication with a lower opening of the drain passageway. The drain passageway has a first section proximate the base wall defining a first cross-sectional area and a second section distal the base wall defining a second cross-sectional area. The second cross-sectional area is less than the first cross-sectional area and this reduction in cross-sectional area produces a head pressure that increases the flow out of the lower opening.

## Background
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the benefit of U.S. Provisional Patent Application No. 62/298,159 filed Feb. 22, 2016, which is hereby incorporated by reference for all purposes as if set forth in its entirety herein.


STATEMENT OF FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
TECHNICAL FIELD
This disclosure relates to drains and, in particular, trench drains for use proximate the threshold of an elevator door to prevent water from flowing down an elevator shaft.
BACKGROUND
Nearly all multi-story buildings are required to have fire prevention systems installed. Such fire prevention systems include water lines and sprinklers which, in the event of the detection of a fire, can distribute large volumes of water in the vicinity of a fire. Such fire prevention systems are particularly of importance in multi-story buildings because, in the event of a fire, there may not be an easy way for firefighters at ground level to get several stories up before the fire has had a chance to spread.
However, it is also often the case that multi-story buildings are not well-equipped to accommodate the drainage of such large volumes of water, especially above ground level. In many instances, if the building includes one or more elevators, then the water provided by the fire prevention system collects on the floors above ground level and may have a tendency to flow down the elevator shaft. Because there is the possibility that both the elevator car and other equipment may exist between the floor and the elevator pit, water drainage into the elevator shaft is to be avoided.
Some drainage systems have been developed to address this problem. See e.g., PCT International Publication No. WO 98/22381 and U.S. Pat. No. 8,800,226. Such systems generally route water laterally into vertical pipes to limit the amount of water entering the open elevator shaft.
SUMMARY
However, the current state of the art drains either need to have great depth to account for the volumes of water that flow therethrough or run the risk of having water overflow from the drain into the elevator shaft.
To prevent draining of water into an elevator and to avoid needing have a deep drain, an improved elevator trench drain is disclosed herein with a low profile that still accommodates high flows of water therethrough. This elevator trench drain may be located at a lower threshold of an elevator door between the floor of the building and the elevator shaft. In this position, any water that collects on the floor (due to, for example, a sprinkler system operating) may be collected in the elevator trench drain and controllably routed to a drainage pipe, rather than simply flowing down into the open elevator shaft. Among other things, this drain can have a low profile, can have a multi-diameter drain opening that builds a head pressure to increase flow out of the drain, and can have a hinged grating for easy installation and access to the trench.
According to one aspect, an elevator trench drain includes a trench and a drain passageway. The trench includes a base wall with peripheral side walls that extend upwardly from the base wall to a trench volume therein. The drain passageway extends downwardly from the base wall of the trench and places the trench volume in fluid communication with a lower opening of the drain passageway (which may be in connection with further drain pipes for routing of the collected water). The drain passageway has a first section proximate the base wall defining a first cross-sectional area and a second section distal the base wall defining a second cross-sectional area. The second cross-sectional area is less than the first cross-sectional area and this reduction from the first cross-sectional area to the second cross-sectional area creates a head pressure that increases the flow out of the lower drain passageway opening during use.
An elevator trench drain of this type may be disposed proximate a lower edge of an elevator door to assist in drainage in the event that water collects on the floor of a multi-story building and to prevent water from draining into the elevator pit in an uncontrolled fashion.
In many forms, the elevator trench drain will have a grating. In some forms, this grating may be hingedly connected to the trench. To provide this hinged connection, the peripheral side walls of the trench may have a pair of opposing elongated slots formed in them and the grating may have a pair of posts on opposing ends thereof. Each of the pair of posts on the grating can be received in a respective one of the pair of opposing elongated slots of the trench to establish an axis of rotation and to permit the assembly/disassembly of the grating to the drain by temporarily axially misaligning the posts relative to the slots. In some forms, the pair of opposing elongated slots may be integrally formed in the peripheral sidewalls of the trench (by welding or casting, for example). It is contemplated that in some forms, each of the slots may positively extend inwardly into the trench from the sidewall. For example, the pair of opposing elongated slots may each be a wall that extends generally perpendicularly from the peripheral side wall of the trench volume and this wall may form a closed loop forming one of the slots into which one of the posts of the grating is received.
With respect to the drain passageway, the first section may have a first distance of downward extension having the first cross-sectional area which is constant along the first distance of downward extension and the second section may have a second distance of downward extension having the second cross-sectional area which is constant along the second distance. In some forms, the first section and the second section may each be tubular and the first and second cross-sectional areas may both be circular. An intermediate section may be between the first section and the second section of the drain passageway in which the intermediate section continuously connects the first section to the second section and reduces in diameter between the two sections. The intermediate section may extend over a distance of downward extension and gradually tapers inward from the first section to the second section. This intermediate section may be frusto-conical but may have other types of taper. For example, the first section and the second section may have vertically-extending walls and the intermediate section may be angled 45 degrees relative to the vertically extending walls as the intermediate section extends downward and inward from the first section to the second section. Alternatively, it is contemplated that the reduction in cross section could occur in a single step or may have alternative angular tapers.
In some forms, the drain passageway may be centrally aligned in the base wall of the trench while, in other forms, the drain passageway may be offset from the center in the base wall of the trench. Such variations may be made depending on the particular structure in which the drain is used.
In some forms, the peripheral side walls of the trench may include two pairs of linear parallel segments such that the trench is rectangular in shape. In some forms, a flange may be disposed outward of the peripheral side walls. Once installed, floor coverings (for example, tile, carpet, and so forth) may cover this flange. In other forms of the drain, this flange may be absent.
In some forms, to provide sufficient head pressure in the drain passageway, a ratio of a diameter of the first section to a diameter of the second section may be 1.5 or may be more generally in a range of 1.4 to 1.6.
In some forms, a depth of elevator trench drain exclusive of the drain passageway may be 1.75 inches. Among other things, this minimizes the height requirement for the installation of the elevator trench drain into the floor (which takes up the inter-story space between adjacent floors). Despite have relatively shallow depth, the drain passageway of the elevator trench drain may be configured to permit the flow of 100 gallons per minute or more of water therethrough.
These and still other advantages of the invention will be apparent from the detailed description and drawings. What follows is merely a description of some preferred embodiments of the present invention. To assess the full scope of the invention, the claims should be looked to as these preferred embodiments are not intended to be the only embodiments within the scope of the claims.



BRIEF DESCRIPTION OF THE FIGURES
FIG. 1 is a perspective view of an elevator trench drain in which a grating is closed over the trench.
FIG. 2 is a perspective view of the elevator trench drain of FIG. 1 in which a grating is hinged open, revealing the inner volume of the trench and the top side of the drain passageway.
FIG. 3 is a detailed exploded book view of one side the hinge connection between the grating and the trench illustrating how the post of the grating is received in the slot of the trench.
FIG. 4 is a detailed cross-sectional side view of the drain passageway of the elevator trench drain illustrating the reduction in cross-sectional area from the top section to the bottom section of the drain passageway.
FIG. 5 is a detailed top view of drain passageway further illustrating the profile of the upper and lower sections of the drain passageway as seen from above.



DETAILED DESCRIPTION
Referring first to FIGS. 1 and 2, an elevator trench drain 10 is illustrated in closed and opened positions, respectively. An elevator trench drain of this type is designed to be installed along the width of the lower edge or threshold of an elevator door. This drain can provide a drainage pathway for fluids, for example water from sprinkler systems. In the absence of such a drain in a situation in which a sprinkler system has been activated, water from the system might collect on the floor and potentially drain into the elevator or elevator shaft. If that were to happen, the elevator system could malfunction in the event of an emergency or be otherwise damaged.
The elevator drain 10 is generally rectangular in the exemplary form shown; however, in other forms, the elevator trench drain 10 may have generally different shapes or aspect ratios which may be custom to the particular application. Because the exemplary elevator trench drain 10 is rectangular, it extends between a pair of lateral ends 12 and 14 which define an overall length of the assembly and extends between a pair of forward and backward ends 16 and 18 which define an overall width of the assembly.
In the illustrated assembly, the elevator trench drain 10 has two main parts including a trench 20 and a grating 22. During use, the water will flow through the grating 22 and collect in the trench 20, though which the water is subsequently drained or evacuated.
The trench 20 has a base wall 24 with peripheral side walls 26 extending upwardly from the base wall 24. Because the particular drain 10 is rectangular, the peripheral side walls 26 include a pair of lateral side walls 28 and 30, a front wall 32, and a rear wall 34. In aggregate, the various walls of the trench 20 defining a trench volume 36 inside the trench 20. In the instant case, this trench volume 36 is generally rectangular in shape being established by the base wall 24, the pair of lateral side walls 28 and 30, the front wall 32, and the rear wall 34.
The various peripheral side walls 26 of the trench 20 also include an inwardly extending step 38 between an upper peripheral lip 40 and the base wall 24 that defines a grating seat 42 for the reception of the grating 22. In the form illustrated, this step 38 occurs approximately halfway between an upper surface 44 of the upper peripheral lip 40 and the base wall 24. During use, water flowing into the trench 20 may also collect (at least to some extent) in the trench volume 36 partially occupied by the grating 22.
The trench 20 may also include features that assist in the installation of the elevator trench drain 10 into the floor, although such features may not be found in all designs. In the particular form illustrated, the trench 20 includes an outwardly-extending peripheral flange 46 that is offset slightly downward from the upper peripheral lip 40. This peripheral flange 46 may receive floor coverings (for it, carpet, tile, cast materials such as concrete) over it such that the top of the floor covering is roughly flush with the upper surface 44 of the upper peripheral lip 40. There may also be anchor straps 48 that extend outwardly past the flange 46 which are employed during the installation of the trench 20 into the surrounding building structure.
With brief forward reference being made to FIG. 3, to hingedly receive the grating 22 in the trench 20, each of the lateral side walls 28 and 30 may include a slot 50 formed therein such that the slots 50 collectively define a pair of opposing slots. In the particular form illustrated in FIG. 3, the slot 50 is formed above the step 38 in the lateral side walls 28 and 30 proximate the rear wall 34. To accommodate entry of the respective post 52 on the grating 22, these slots 50 are elongated in the front to rear direction such that the grating 22 may be slightly twisted relative the trench 20 and the eventual hinged axis of rotation to provide sufficient clearances for assembly of the posts 52 into the slots 50. In the form illustrated, the slots 50 are integrally formed in the peripheral side walls 26 of the trench 20 and are formed by a wall 54 that extends generally perpendicularly from the peripheral side wall 26 of the trench 20 and forms a closed loop that establishes the slot 50.
With particular reference now being made to FIG. 4, the trench 20 includes a drain passageway 56 that extends downwardly the base wall 24 of the trench 20. As illustrated, the drain passageway 56 is centrally located along the width and length of the trench 20. However, it is contemplated that the drain passageway 56 might be located otherwise such as, for example, at one end of the base wall 24 of the trench 20 or offset from center in one or both of the length and width directions. This drain passageway 56 places the trench volume 36 (at an upper opening 58 formed in the base wall 24) in fluid communication with a lower opening 60 of the drain passageway 56. The lower opening is typically connected in use to a drain pipe such as a 4 inch drain pipe for further routing of the drained water.
As best seen in FIGS. 4 and 5, the drain passageway 56 has multiple sections as it extends downwardly from the upper opening 58 to the lower opening 60. In the particular form illustrated, there are three sections including an upper section 62 proximate the upper opening 58 in the base wall 24, a lower section 64 proximate the lower opening 60 of the drain passageway 56, and an intermediate section 66 between the upper section 62 and the lower section 64. The upper section 62 and the lower section 64 each have a constant respective cross-sectional area over their axial height or distance of extension. In the illustrated embodiment, the upper section 62 is circular having a diameter of 6 inches and the lower section 64 is circular having a diameter of 4 inches (to match standard drain pipe which is connected to the outlet). The intermediate section 66 between the upper section 62 and the lower section 64 includes an approximately 45 degree taper that transitions the diameter between the respective sections 62 and 64 above and below it. Although the taper is illustrated as extending entirely from the first section to the second section, it is contemplated that there may be more than one differently angled tapered regions or radially extending step in this intermediate section. While circular cross-sections are found in the illustrated design as can be best seen in FIG. 5, it is contemplated that other drain cross sections might also be used if those reduce in cross-section area from the upper section to the lower section.
Among other things, the profile of this drain passageway 56 helps to improve the flow rate of water collecting in the trench 50 through the drain passageway 56. The upper section 62 creates a head pressure which causes the acceleration of the water flowing downward into the lower section 64. Although it is contemplated that the intermediate section 66 might be omitted (i.e., that there could simply be a flat step between sections 62 and 64 which is perpendicular to the central axis of the drain passageway 62), the taper or angling of the intermediate section 66 can further enhance the flow from the upper section 62 to the lower section 64 because it assists in directing the flow of the water in a non-turbulent manner from the upper section 62 into the lower section 64. Among other things, the reduction in diameter to improve and increase flow rate can help enable a low profile (i.e., thin) design so that the elevator trench drain 10 may be installed in smaller spaces without increasing the depth of the floor to accommodate for the drain.
Some exemplary and non-limiting dimensions are now provided for the trench 20. The height of the trench 20 is contemplated as being typically 1.75 inches overall (exclusive of the drain passageway 56), although other depths may also be used depending on the installation context or needs of the customer. A typical width may be 13.5 inches overall with an 11.4375 inch grating seat area. The finished perimeter flange may be approximately 1 inch from the upper peripheral lip 40. The overall length of channel may typically be in a range of 38 to 120 inches. The drain passageway 56 is illustrated as being hydraulically engineered from 6 inches to 4 inches in a funnel style outlet to increase head pressure on the 4 inch section to promote flow (with flow in excess of 100 gallons per minute being targeted in many conditions to meet code and achieved using this passageway structure). This ratio of the diameters from the first section to the second section is approximately 1.5 (6 inches to 4 inches), but it is contemplated that other similar ratios may also be used, for example, in the range of 1.3 to 1.7 or more narrowly in the range of 1.4 to 1.6. The entire trench construction may be provided in Type 304 stainless steel but may also be in Type 316 stainless steel in certain applications or based on customer preference.
The grating 22 is also generally rectangular in shape to match and fit into the grating seat 42 of the trench 20. The exemplary grating 22 includes a plurality of lengthwise-extending bars 68 which are joined to a plurality of widthwise-extending supports 70 to form a grid. However, in other forms, the grating pattern may be different or otherwise embellished to provide a desired aesthetic appearance. On the rear side of the grating 22, there are a pair of oppositely facing posts 52 that are located for reception into the slots 50 of the trench 20 as illustrated in FIG. 3.
As noted above, by angularly twisting the axis of the posts 52 (which are co-axial with one another) they can be slid into the slots 50 of the trench 20 to provide a hinged connection to open the grate as generally illustrated in FIG. 2. There may be some range of motion restrictions depending on the depth of the grating seat 42 and the placement of the posts 52 on the grating 22.
The grating 22 may be a stainless steel wire grating and may be approximately 2 inches shorter than the specified channel length to accommodate installation of the grating 22 into the trench 20 and provide some side clearances. As with the trench 20, the grating 22 may be manufactured from Type 304 stainless steel or Type 316 stainless steel. In one exemplary form, the grating 22 may features an open area of 64.9 square inches per linear foot of grating. Wires, bars, and supports may be held by press fit and welded to support trusses (i.e., the bars 68 may be press fit and welded into supports 70 or vice versa). Some gratings may be a fabricated stainless steel slotted grate with an open area of 35.9 square inches per linear foot. In some forms, grating height may be 29/32 inches tall and grating width may be 11.375 inches wide.
Accordingly, an elevator trench drain is disclosed that accommodates high flow rates (up to and exceeding 100 gallons per minute) without having a deep trench depth or necessarily having multiple outlets to accommodate slower flows. The improved drain passageway permits high flow rates without compromising other dimensions of the product or complicating the drain system with additional, multiple fluid connections.
It should be appreciated that various other modifications and variations to the preferred embodiments can be made within the spirit and scope of the invention. Therefore, the invention should not be limited to the described embodiments. To ascertain the full scope of the invention, the following claims should be referenced.

## Claims

1. An elevator trench drain comprising:
a trench having a base wall with peripheral side walls extending upwardly therefrom, the trench defining a trench volume therein; and
a drain passageway extending downwardly from the base wall of the trench and placing the trench volume in fluid communication with a lower opening of the drain passageway, the drain passageway having a first section proximate the base wall defining a first cross-sectional area and a second section distal the base wall defining a second cross-sectional area in which the second cross-sectional area is less than the first cross-sectional area;
wherein a reduction from the first cross-sectional area to the second cross-sectional area creates a head pressure that increases the flow out of the lower opening and wherein the drain passageway of the elevator trench drain is configured to permit the flow of 100 gallons per minute or more of water therethrough.

2. The elevator trench drain of claim 1, comprising a grating hingedly connected to the trench.

3. The elevator trench drain of claim 2, wherein the peripheral side walls of the trench have a pair of opposing elongated slots formed therein and the grating has a pair of posts on opposing ends thereof and wherein each of the pair of posts on the grating are received in a respective one of the pair of opposing elongated slots of the trench.

4. The elevator trench drain of claim 3, wherein the pair of opposing elongated slots are integrally formed in the peripheral sidewalls of the trench.

5. The elevator trench drain of claim 3, wherein the pair of opposing elongated slots are a wall extending generally perpendicularly from the peripheral side wall of the trench volume and wherein the wall forms a closed loop forming one of the slots into which one of the posts of the grating is received.

6. The elevator trench drain of claim 1, wherein the first section has a first distance of downward extension having the first cross-sectional area which is constant along the first distance of downward extension and wherein the second section has a second distance of downward extension having the second cross-sectional area which is constant along the second distance.

7. The elevator trench drain of claim 6, further comprising an intermediate section between the first section and the second section of the drain passageway in which the intermediate section continuously connects the first section to the second section and reduces in diameter therebetween.

8. The elevator trench drain of claim 7, wherein the intermediate section extends over a distance of downward extension and the intermediate section gradually tapers inward from the first section to the second section.

9. The elevator trench drain of claim 8, wherein the intermediate section is frusto-conical.

10. The elevator trench drain of claim 8, wherein first section and the second section have vertically-extending walls and wherein the intermediate section is angled 45 degrees relative to the vertically extending walls as the intermediate section extends downward and inward from the first section to the second section.

11. The elevator trench drain of claim 6, wherein the first section and the second section are each tubular such that the first cross-sectional area is circular and the second cross-sectional area is circular.

12. The elevator trench drain of claim 1, wherein the peripheral side walls of the trench include two pairs of linear parallel segments such that the trench is rectangular in shape.

13. The elevator trench drain of claim 1, wherein the drain passageway is centrally aligned in the base wall of the trench.

14. The elevator trench drain of claim 1, wherein the elevator trench drain is configured to be disposed proximate a lower edge of an elevator door.

15. The elevator trench drain of claim 1, further comprising a flange disposed outward of the peripheral side walls.

16. The elevator trench drain of claim 1, wherein a ratio of a diameter of the first section to a diameter of the second section is 1.5.

17. The elevator trench drain of claim 1, wherein a ratio of a diameter of the first section to a diameter of the second section is in a range of 1.4 to 1.6.

18. The elevator trench drain of claim 1, wherein a depth of elevator trench drain exclusive of the drain passageway is 1.75 inches.

19. The elevator trench drain of claim 1, wherein the trench further comprises an inwardly extending step, the inwardly extending step extending inwardly away from at least one peripheral side wall and extending upwardly away from the trench base wall to form a grating seat.

20. The elevator trench drain of claim 19, wherein the peripheral side walls have an upper surface defining an upper peripheral lip, and the inwardly extending step has a grating seat surface extending inwardly away from approximately halfway between the upper peripheral lip of the at least one peripheral side wall and the trench base wall.

21. The elevator trench drain of claim 20, wherein the trench further comprises an outwardly extending peripheral flange extending away from the upper peripheral lip and having a top surface offset downward from the upper peripheral lip.

22. An elevator trench drain comprising:
a trench having a base wall with peripheral side walls extending upwardly therefrom, the trench defining a trench volume therein;
a drain passageway extending downwardly from the base wall of the trench and placing the trench volume in fluid communication with a lower opening of the drain passageway, the drain passageway having a first section proximate the base wall defining a first cross-sectional area and a second section distal the base wall defining a second cross-sectional area in which the second cross-sectional area is less than the first cross-sectional area; and
a grating hingedly connected to the trench;
wherein a reduction from the first cross-sectional area to the second cross-sectional area creates a head pressure that increases the flow out of the lower opening and wherein the peripheral side walls of the trench have a pair of opposing elongated slots formed therein and the grating has a pair of posts on opposing ends thereof and wherein each of the pair of posts on the grating are received in a respective one of the pair of opposing elongated slots of the trench, and wherein the pair of opposing elongated slots are a wall extending generally perpendicularly inward from the peripheral side wall of the trench volume and wherein the wall forms a closed loop forming one of the slots into which one of the posts of the grating is received, and wherein the elongated slots have a volume defined by the wall extending generally perpendicularly inward from the peripheral side wall of the trench volume and an interior surface of the peripheral side wall.

23. The elevator trench drain of claim 22, wherein the trench further comprises an inwardly extending step, the inwardly extending step extending inwardly away from at least one peripheral side wall and extending upwardly away from the trench base wall to form a grating seat.

24. The elevator trench drain of claim 23, wherein the peripheral side walls have an upper surface defining an upper peripheral lip, and the inwardly extending step has a grating seat surface extending inwardly away from approximately halfway between the upper peripheral lip of the at least one peripheral side wall and the trench base wall.