Fluid handling – Back flow prevention by vacuum breaking – Air vent in liquid flow line
Reexamination Certificate
2001-06-01
2003-01-28
Michalsky, Gerald A. (Department: 3753)
Fluid handling
Back flow prevention by vacuum breaking
Air vent in liquid flow line
C137S216100
Reexamination Certificate
active
06510863
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an air gap particularly adapted to vent the waste water discharge from one or more household dishwashers and the waste water discharge from a reverse osmosis (RO) system.
2. Description of the Prior Art
Most plumbing codes specify that an anti-siphon device or air gap be provided to vent waste water discharge from household primary waste water sources such as dishwashers and the like. The air gap includes a vent chamber or space through which the waste water passes. This space is vented to atmosphere to prevent the establishment of a vacuum that could result in back siphoning of the contaminated dishwasher water back into the household water supply system.
Many prior art “single inlet” air gaps are capable of venting the waste water discharge from a single primary source such as a dishwasher or the like.
One such single inlet air gap has come into such widespread use that it has become more or less standard in the trade. The air gap body is molded or otherwise formed of plastic material into a unitary or one-piece structure which includes a central leg constituting an outlet conduit or port that discharges all of the waste water coming from the air gap body into a household drain line for emptying into the sewer. The air gap body also includes a laterally divergent leg constituting a single inlet conduit or port through which waste water enters the air gap body.
The inlet port of the single inlet air gap body is clamped or otherwise attached to a dishwasher hose to receive the dishwasher waste flow and pass it to the air gap body. The discharge port of the air gap body empties all waste from the air gap body to a sewer pipe or the like via a household garbage disposer, if there is one, or directly to a household drain line connected to the sewer pipe.
Waste water entering through the inlet port from a dishwasher or from an RO drain line passes upwardly through the air gap body, where a flow diverter at the top of the body reverses the direction of waste flow downwardly through a space or spaces located interiorly of the air gap body for venting to atmosphere. Such venting prevents development of a vacuum that might cause suction or back siphoning of waste water into the reverse osmosis (RO) unit and contaminate the household water supply.
Dishwasher waste water is discharged in relatively high volumes and at a relatively high rate of flow. In contrast, waste water flow from an RO system is of relatively low volume and flows at a relatively low rate. Both such low and high volume and rate flow must be vented to prevent back flow or back siphoning of RO waste water flow into the household water system.
There is a need in the prior art for an air gap capable of venting more than one source of waste water. Insofar as applicant is aware, no such air gap is presently available. This is a particular problem where a householder owns two dishwashers or “dishwasher drawers” incorporated in a single dishwasher. Such drawers are generally equivalent to two separate dishwashers, offering flexibility in handling different kinds and sizes of loads, different washing and drying temperatures, and different timing and sequence of operation of the typical dishwasher cycles. Use of an RO system in the household adds yet another source of waste water.
Heretofore the venting of such an installation would require two or more separate air gaps. This would necessitate drilling a large hole or holes in the sink or counter top in addition to the hole already provided for use with one dishwasher. Providing such additional installation holes would be time consuming, expensive, and unsightly.
SUMMARY OF THE INVENTION
According to the present invention, a unitary or one piece twin or dual inlet air gap body is provided which includes multiple inlets for a pair of dishwashers or dishwasher drawers and for an RO unit. All three of these inlets can be vented using an air gap having a pair of inlet ports for receiving multiple flows of waste water.
The present dual inlet air gap is characterized by waste flow and venting passages whose rates of flow and dimensions are very close to those of the single inlet air gap presently in wide use.
The dimensions of the air gap body enable it to be mounted in the standard size sink or counter top hole that is provided for a single inlet air gap. The inlet and outlet conduits have dimensions similar to those of the single inlet air gap so that they can be connected to the same sizes of dishwasher and garbage disposer hoses. In addition, the present dual inlet air gap body is threaded or otherwise adapted to be seated within a single sink or counter top hole in a manner similar to the mounting of the prior art single inlet type of air gap. It is provided with threads or other connection means so that it can be connected to mounting elements like those now used for a single inlet air gap.
Of particular importance is the provision of dual inlet ports which each have an inner diameter like that of a single inlet air gap so that each of the inlet ports can handle the waste flow from one of the dishwasher drawers of the newly emergent dishwasher designs. Further, in the regions where the two inlet ports enter the central portion of the air gap body, their internal walls are optimally curved, formed or shaped to provide a waste flow essentially the same in volume, rate of flow and pressure drop as that of a conventional single inlet air gap.
What has just been said about the characteristics of each dual inlet port is of course true of the upper extremities of the inlet ports which extend upwardly through the air gap body to the flow reversal fitting. These and other modifications enable the present dual air gap to substantially meet the same physical and functional plumbing code requirements that apply to single inlet air gaps.
The dual inlet air gap has also been configured to fit through the same standard sink opening that is provided for a single air gap, to use the same hose fittings and other connections common to a single inlet air gap, and to adjust the venting spaces and passages to vent both discharges from the dual inlet air gap at a rate comparable to the specifications for a single inlet air gap.
Thus, it is an important feature of the present invention that the dual inlet air gap provides separate venting for two dishwashers, or for the two drawers of a single dishwasher, just as would be provided by two separate air gaps. In addition, the water flow and vent passages are sufficiently isolated from each other that there can be no siphoning of contaminated water from one dishwasher to the other and consequent contamination of the household water supply.
It is also a feature of the present invention that the upper extremity of one of the inlet ports, which usually carry only waste water from a dishwasher or the like, can be modified to serve as an RO inlet port for receiving RO waste water. Such a modification can easily be done by the manufacturer or by the air gap installer. Also, movement of a component of the modified inlet port can be made between a projected position to stop all flow, and a retracted position which allows RO water to flow. The conversion is quickly and easily accomplished and adds a unique capability to the inlet port.
In every respect possible the present dual air gap with its unique cap portion design and unique one-piece main housing design has been made to function like a pair of single inlet air gaps whereby it can be used as a “standard” air gap for universal use in venting a pair of primary waste sources, just as the most popular single air gap now available has become more or less “standard”. Moreover, the present dual air gap is not significantly more expensive or complex than a single inlet air gap body.
As above indicated, the RO unit of an RO system, and specifically the drain line tubing, can also be vented by the present dual inlet air gap simultaneously with the venting of two dishwasher drawers. The low volume, low flow character of RO waste di
McLellan Joseph F.
Michalsky Gerald A.
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