Patent Application
20190093325
No cross reference is made to other applications.
No Federal Government support was received in the development of this Invention.
No sequence listing, table, or computer program is attached or accompanies this Application.
This Invention relates generally to trap fittings connected to lavatory sinks, and more particularly to covers for traps fitted to lavatory sinks.
The advent of accessibility requirements in public and private buildings have led to a category of products comprising covers that fit to the trap of a sink. The design intention of trap covers is to prevent the legs and knees of a wheelchair user using a sink from suffering skin burns owing to not being able to sense the hot temperature of drainage water passing from the sink vessel, around the bent portion of the trap, to the sewerage system. The bent portion has many trade names; in this Application the bent portion is variously referred to as a U-bend owing to the U-shape of the bend of a removable cast trap, or J-bend in the case of a tubular trap. The first design objective of covers of a U-bend or J-bend trap has been burn protection; however, patented designs fail to accommodate other important design objectives of a trap cover arising from other safety requirements in trap design. In order to understand what these safety requirements are, it is necessary to carefully describe the modern North American sink trap, and pertinent safety objectives for traps. Following which, the failures of existing patents for trap covers can be understood, and how this Application addresses these safety objectives is discussed.
Traps in plumbing are devices originally devised to contain sewer gas from rising from a municipal or septic tank sewage system up into a plumbed building via the drain hole on washing vessels. Usually gas ingress is halted by the trapping of a quantity of water between a vessel drain and a sewage system, although hinged and sprung hatches with rubber seals are also used in less developed nations. Trap systems consist of the vessel they are connected to, as well as the drain fitting connecting a vessel fixture to a drainage pipe called a “tailpiece”, as well as the sealing connecting assemblies that connect a tailpiece to a trap fitting, and finally a horizontal waste arm called a “wall bend” leading to a vented vertical drainage pipe or “stack” connecting and draining many fixtures. The vessel of interest in this Application is called a “lavatory” or “sink” or even “lavatory sink”, all three names referring to a hand washing or hand hygiene sink. The lavatory sink is secured to a wall or counter and equipped with pressurized supply water fittings terminating in a faucet or faucets that supply water to the lavatory interior. The environment of interest in this Application is the accessible public environment, for example, hospitals. Current to the date of this Application, most traps in North America are required by building codes to be plastic or metal including a bent form trapping water and connected with various connection and sealing assemblies. Colloquially, a trap assembly made of tubular metal or plastic connected to a lavatory is called a “P-trap” owing to its similarity in shape to the letter “P” in a horizontal position. The portion of the tube bent 180 degrees can also referred to as the “J-bend” owing to the upstream arm of this part being higher than the downstream arm. Plumbing codes specify that there must be a visible separation in the J-bend between the two upward tubular arms of the bended part. In contrast, a detachable trap part comprising tube bent 180 degrees at the tube midpoint to form two upward arms of equal length is called a “U-bend”. When a U-bend is used, it is mechanically attached to an upper mount that preserves the higher arm on the upstream arm. Additionally, other manufacturing methods of the U-bend, such as casting, moulding, and forging, may be preferable or necessary to achieve design objectives not possible with bent tube. Note that even in the case of a detachable U-bend, the sink drain will always be located vertically above the downstream outlet of a trap, resembling a J-bend in appearance.
Knowledge of basic trap design allows for understanding of safety objectives in trap design, in turn critical for trap cover design. Trap design objective one: water must drain freely from the sink vessel to the downstream sewage system through the trap, to prevent pooling and overflow in the vessel. Trap design objective two: a trap should be designed to allow cleaning in the case of blockage, to prevent pooling and overflow in the vessel. Trap design objective three: a bend should be provided in the trap water channel (most often a pipe bent to render the upstream and downstream portion parallel while still connected). Trap design objective four: a bend provided in the trap shall provide a weir on the downstream side high enough to retain a volume of trapped water sufficient to not be siphoned downstream when the water is run in the vessel, in order that the trap water barrier to sewer gases arising from the sewer should not be compromised, also, the greater volume of water provides a more massive resistance to any pressure of sewer gas entry into the room wherein the sink is provided. Trap design objective five: a trap should be equipped with a visual separation between the upstream portion of the U-bend and the downstream portion of the U-bend, in order to immediately identify a perforation in the wall between the downstream and upstream channels, as said perforations in said wall may allow sewer gases to bypass the full height of the trap water and thereby enter the room, noting that such a failure will be identified by dripping on the floor. Trap design objective six: a trap should be made of durable and cleanable materials that are easily accessed for maintenance of hygiene and optimally be antimicrobial. Trap design objective seven: no part of a trap shall allow drainage water to collect outside of the main drainage channel, in case said collected water may be contaminated and recontaminate trap water via the perforations through which the collected water originally escaped the trap interior. These seven safety design objectives will be sufficient to clarify the failures of previous trap cover patents, and this patent evolution can traced in the history of trap design.
The history of modern trap starts largely with Thomas Crapper in England, who found that vectoring toilet waste with flush water into a tank pit equipped with an overflow prevented the ingress of sewer gas into the household. However, said pit traps posed a cleaning nightmare. Modern interpretations of Crapper's trap for the lavatory sink have generated a variety of patent applications, each illustrating important aspects of trap design. As a sample, Nunez (U.S. Pat. Appln. No. US 2004/0177439, Sep. 16, 2004) provides instead of a P-trap, an egg-shaped receptacle accepting the drainpiece from above and equipped with a waste arm to the side. If the bottom of said tailpiece is inserted such that its bottom end lies below the lowest point of the diameter of the exit port to the waste arm (commonly this lowest exit point downstream to the trap is called the “weir”), Nunez considered that this would be a sufficient barrier to trap gases as well as easy to clean. North American plumbing codes have all rejected this style of trap, called the “bottle trap” owing to its superficial resemblance to a beer bottle, for two reasons. One rejection reason is that siphonage can occur more easily without at least two inches of trap height to the weir. If water is siphoned out of the trap, this can lead to an empty trap, defeating its very purpose. More importantly, it is impossible to visually assess whether the tailpiece from the drain is below the weir by looking at the exterior of the trap. What happens often is that a long tailpiece extended even 2″ below a weir will develop perforations above the weir. In this case, gases short circuit the trap, again defeating its very purpose. Bacon (U.S. Pat. Appln. No. US 2009/0308463, Dec. 17, 2009) presents another bottle trap that does indeed have an integral barrier inside to preserve the two inch to weir trap height that resists siphoning. However, there is no way to visually assess that that barrier is not perforated without disassembling it, and even then assessment of the integrity of the integral barrier would be difficult. Bottle traps have therefore been expressedly defined and banned in all building codes in Canada and the United States. Instead, a P-trap with a visual separation is specified. Again, if one or both walls bounding the gap in the J-bend fail, the trap will leak to the ground, an easy visual test. Further, the gap can be sized to preserve a 2″ weir height on the inside of the J-bend to resist siphonage.
The trapping of sewer gases has been stated to be one objective of trap design. Another was cleanability. Ana (U.S. Pat. Appln. No. US 2006/0265804, Nov. 30, 2006) accepts the J-bend and attempts to add a cleanout consisting of a threaded plug and port. The novelty of Ana's application is that the cleanout port is horizontal, provided on the side of the J-bend to more easily accept a cleaning brush. Usually if a threaded clean-out port is provided, it is found on the lowest point of the J-bend. In either case, these tiny cleanout ports are unusable in infection control environments for a variety of reasons, including the unsuitability of any design of brush for cleaning tubes lined with biofilms, and more simply the leaking or corroding of said cleanouts. Beaumont (U.S. Pat. Appln. No. US/2014/0000019, Jan. 2, 2014) present an example of a brushless but high risk cleaning device consisting of a tube connected at the upstream end to water supply, and at the bottom end resting freely in the trap. Independent of its functionality, if the water supply pressure goes negative, as periodically happens, the trap water with its high risk of infection would be directly sucked up into the fresh water supply, with potentially disastrous complications once supply water pressure returns. Any device not equipped with an air gap or other backflow prevention device is strictly illegal. This sort of direct flush can be designed in many ways, all of them strictly forbidden by building codes in Canada and the United States owing to said risk of cross-contamination of potable supply water with infections drainage water. The conclusion from a limited library of trap design applications is that the easiest and safest way to clean a trap is to design a trap that enables the easy and periodic removal of the water-containing 180 degree bend portion of the J-bend. Such a system is described in this application.
The removability of a trap enables other tools in fighting infection spread other than regular cleaning enabled by easy replaceability. These tools include enabling concentration of expense of material and methods into the portion of the trap most likely to support biofilm growth. Construction of the U-bend portion out of material that is inherently anti-microbial, for example certain copper alloys, or coated to be anti-microbial, is less expensive for hospitals when only the removable portion receives this special treatment. Processes such as heating can be incorporated just into the U-tube, and improvements made without discarding the entire trap assembly.
From understanding of the role of safety in the evolution of the design of the trap, it follows that a trap cover should not frustrate this evolution to provide a less safe trap by providing a poorly designed trap cover whose primary design objective is burn prevention for wheelchair-bound users of the sink to which the trap is attached. Design objectives for a cover arise in consideration of trap design objectives. Trap cover design objective one: a means of separating the heated trap surface from the wheelchair-bound users legs shall be provided, to avoid burns. Trap cover design objective two: a trap cover shall be easily wiped clean, to prevent dust collection on the trap. Trap cover design objective three: a trap cover shall be easily removed and replaced, to enable removal of a trap cleanout such as a detachable U-bend, to enable maintenance. Trap cover design objective four: a trap cover shall provide a drain in its base in order that freely allows water dripping from a perforated trap to drip to the floor and provide evidence of trap failure. Trap cover design objective five: a trap cover shall never provide potential for a secondary pool for water to collect even when drain ports are provided, since small drain ports are easily blocked and water leaking out of a perforated trap can collect, become contaminated, and then recontaminate the trap water via the same perforations by which trap escaped the main trap channel. Trap cover design objective six: A trap cover should fit a variety of trap designs and technologies, for the reason that provision of a variety of covers for a variety of trap designs adds expense. A seventh trap cover design objective is aesthetics: the cover should be available in a variety of appearances to match the aesthetic design objectives of the room.
An understanding of trap design leads to an understanding not only of trap design objectives, but to the failures of the two principal trap cover patents, both of which attain the first trap cover design objective of preventing burns to the legs of wheelchair users of the sink. The first significant trap cover design patent was Clarke (U.S. Pat. No. 4,862,528, Sep. 5, 1989). Clarke fails the third trap cover design objective by being fixed to the drain tailpiece, requiring tools to detach the trap cover. Clarke fails the fourth trap cover design objective by not providing an egress for water leaking from a failed trap; instead, Clarke provides a trough to collect water, frustrating the visible separation provided in the trap to which it is attached. Clarke also fails the fifth trap covers design objective by providing a secondary pool in which water can collect, get contaminated, and recontaminate the trap water.
Lechuga (U.S. Pat. No. 7,100,633, Sep. 5, 2006) fails the third trap cover design objective by being fixed to the drain tailpiece permanently. Lechuga fails the fourth trap cover design objective by not providing an egress for water leaking from a failed trap; instead, Lechuga provides a tight sleeve that could collect leaking trap water, frustrating the visible separation provided in the trap to which it is attached. Lechuga fails the fifth trap covers design objective by providing a secondary pool in between the trap and the cover in which water can collect, get contaminated, and recontaminate the trap water. Lechuga also fails the sixth trap cover design objective by only fitting tubular traps and not being able to accommodate new trap form factors.
Accordingly, it is an objection of this Invention to at least partially overcome some of the disadvantages of the prior art.
The Invention, a clip on cover for sink traps, presents a cover for the trap which is clipped onto the vertical portion of the upstream part of the trap by means of a plurality of clips that fit onto the trap. An uppermost clip fits to the diameter of the threaded drain plug. Optional support by a nut adds an advantage over any other slip joint trap by allowing the Invention to also act as a trap support and relieve the weight of the trap from the wall bend. This requires another clip to clip onto the upstream arm of the trap itself. In order that water not collect, a substantial drainage cavity is provided in the base of the cover sized to avoid blockage.
By use of appropriate spacers between the plurality of clips and the cover, the Invention achieves trap cover the first design objective by providing airspace between the trap and the cover, preventing burns. The invention satisfies the second cover design objective two through providing an easily wiped trap cover, to prevent dust collection on the trap. The clips allow easy removal and replacement, to enable removal of a trap cleanout such as a detachable U-bend, to enable maintenance as in the third trap cover design objective. Through provision of a substantial drainage cavity freely allows water dripping from a perforated trap to drip to the floor to provide evidence of trap failure, allowing attainment of the fourth design objective. Trap cover design objective five is achieved since there is no potential for a secondary pool for water to collect. Trap cover design objective six is achieved by provision to fit a variety of trap designs and technologies. The clip on design also allows for a diversity of covers to be used independent of the form factor of the underlying trap.
In the drawings, which illustrate embodiments of the invention:
The Invention described in this Application is a novel clip on cover fitting for a plurality of traps for lavatory sinks. An isometric view of the entire removable cover system is shown in
An exploded view of the Invention described in this Application shows the cover 1 as removed from the trap 3 attached in turn to the sink 2. Attachment points for clips include the threaded diameter of the drain plug 4 with an optional support by a nut 5. If another clip is attached to the internal side of the cover, this second clip can attach to the upstream portion 6 of the trap 3 beneath the slip joint nut 7, providing a novel limiter on slip joint movement. Sinks are well mounted, particularly in hospital; therefore, by hanging the weight of the trap 3 on the drain plug 4 hanging from and cinched to the sink 2 by means of a cinch nut 8, the majority of the weight of the trap can be borne by the sink mount, allowing for heavy traps to be used. This also has the effect of relieving strain on the wall bend 9, the most fragile part in a trap assembly since it is suspended horizontally from the stack.
A rear view of the Invention shows the case of two clips, an upper clip 10 and a lower clip 11, and any of a plurality of spacers 12 attaching the clips to the cover 1.
