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Publication numberUS3774187 A
Publication typeGrant
Publication dateNov 20, 1973
Filing dateFeb 16, 1972
Priority dateFeb 16, 1972
Publication numberUS 3774187 A, US 3774187A, US-A-3774187, US3774187 A, US3774187A
InventorsWindham R
Original AssigneeWindham R
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Sewage back-up sensor assembly
US 3774187 A
A float operated, unit handled sensor assembly is mounted in the clean-out branch of a lateral sewage disposal line with the float element thereof positioned at a subterranean level intermediate the sewage disposal line and the lowest of the associateed plumbing fixtures located within the plumbing system served by the disposal line. Elevation of the float as a function of sewage blockage downstream of the conventional clean-out branch actuates an alarm at a point in time sufficiently early to permit clearing of the obstruction without back-up through the plumbing facilities while yet permitting limited or inadvertent use of the same.
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Description  (OCR text may contain errors)

United States Patent 1 Windham 1 Nov. 20, 1973 SEWAGE BACK-UP SENSOR ASSEMBLY Robert L. Windham, 1P.O. 1514, Sherman St., Arlington, Tex. 7601 Filed: Feb. 16, 1972 Appl. No.: 226,900


US. Cl. ....340/243, 340/244 A Int. Cl. G08b 21/00 Field of Search 340/243, 244;

References Cited UNITED STATES PATENTS 2,985,187 5/1961 Hamilton 340/244 A UX 3,185,789 5/1965 Gunther 340/244 A UX FOREIGN PATENTS OR APPLICATIONS 28,611 12/1896 Great Britain 340/243 167,359 8/1921 Great Britain 340/243 Primary Examiner-John W. Caldwell Assistant Examiner-Daniel Myer AttorneyColton and Stone 57 ABSTRACT A float operated, unit handled sensor assembly is mounted in-the clean-out branch of a lateral sewage disposal line with the float element thereof positioned at a subterranean level intermediate the sewage disposal line and the lowest of the associateed plumbing fixtures located within the plumbing system served by the disposal line. Elevation of the float as a function of I sewage blockage downstream of the conventional clean-out branch actuatesan alarm at a point in time sufficiently early to permit clearing of the obstruction without back-up through the plumbing facilities while yet permitting limited or inadvertent use of the same.

6 Claims, 3 Drawing Figures 1 SEWAGE BACK-UP SENSOR ASSEMBLY BACKGROUND OF THE INVENTION The invention relates that class of detection sensors which areadapted to and sound an alarm upon blockage of a sewage line. Exemplary prior art disclosures appear in U.S. Pat. Nos. 2,761,037; 2,985,187 and 3,202,165.

It is well understood by those skilled in the art that initial sewage blockage normally takes place at a subterranean location in the lateral sewage disposal line downstream of the junction thereof with those sewage drains serving a particular building. In recognitionof this fact, a branched conduit is conventionally installed in the main sewage disposal line at a position exterior of the serviced building with a capped, access branch thereof extending upwardly to the surface through which maintenance access may be had to the lateral disposal line for cleaning the same.

The sewage warning systems known to the prior art have failed to take advantage of the conventional placement of such clean-out access branches for the positionment of detection sensors but have, instead, relied upon specially constructed pipe fittings which are, necessarily, positioned at other than a subterranean location exterior of the serviced building. Such arrangements are not only unduly expensive as regards the purchase of extra fittings but their installation by appropriately licensed personnel also involves substantial expense in addition to the necessary alarm installations which are common to any system of the type herein discussed.

One of the greatest disadvantages in the positionment of such a warning detection system within the peripheral confines of the serviced building is thefact that detection of backed up sewage would not occur in some instances before the lower ofa serviced plumbing facility had overflowed and, in others, the detection would be of that backed up sewage level just prior to overflowing the lowest facility.

Although it is perfectly obvious that any warning system should operate before overflow takes place; building construction does not always proceed on the basis of the obvious. Thus assume, for example, a typical residential dwelling lacking basement plumbing outlets and employing a detection sensor positioned in a standpipe drain; it is apparent that a subsequently installed basement plumbing facility will be substantially at or below the level of the sensor. In such case, it is typically an overflow of the basement facility that provides the first indication of sewage back up rather than the sensor provided for that purpose. Exemplary of such an arrangement is that shown in U.S. Pat. No. 2,761,037. A similar disadvantage exists with respect to sensors mounted within other sections of the internal plumbing network as typified by the disclosure in U.S. Pat. No. 2,985,187 which takes no cognizance of lower level facilities.

Even in those situations where the sensor is positioned below the level of the lowest plumbing facility but still within the building confines; the total volume within the plumbing system network upstream of the sensor is relatively small so that an inadvertent or'emergency use of a plumbing facility after the warning system has been activated will yet result in back flow into the building.

Absent the recognition of the aforestated problems and the desirability of utilizing the pre-existaht access branch of a lateral sewage disposal line for the mounting of a sensor assembly; it is apparent that the problems associated with such a mounting system have not been resolved.

One primary desideratum insofar as economy is concerned is that the sensor be a unit handled structure susceptible of adjustment to the inherently variable lengths of the various access clean-out branches so that not more than one basic unit need be inventoried. A corollary requirement is that the sensor not be subject to spurious outputs as a function of transient, high flow rates as might be created by the simultaneous drainage of several plumbing facilities installed in the plumbing system served by the lateral line connecting the system with the sewer main.

SUMMARY OF THE INVENTION A float actuated circuit maker is integrated with a cleanout closure plug as by removable fasteners to form therewith a unit handled sewage detection sensor assembly adapted for suspension in a conventional access branch as by substitution of the attached closureplug for that originally capping the access branch.

The basic purpose of the invention is to suspend a float element in the access branch at a level just above the level of the interconnected lateral sewage disposal line and below the level of the lowest plumbing facility drained by the disposal line to insure that an alarm is sounded, by elevation of the float, prior to the time sewage can back up into the lowest plumbing facility. It will be apparent that the lower the float can be positioned without the introduction of spurious signals, the greater will be the plumbing system network volume within the building confines that can yet accept emergency or inadvertent drainage without producing back flow within the building. The sensor construction herein described includes provision for both coarse and fine adjustments of the float element to accommodate those necessary variations in clean-out branch lengths to position the upper ends of thesame adjacent the surface of varying terrain construction sites. Small variations in cleanout branch length are accommodated by a substitution of spacer elements in the suspension mounting of a float suspending bracket to the closure plug while coarse adjustments may be effected by the addition of a separable float guide stem to lengthen the original guide stem.

The float element, 'per se, is preferably an open ended hollow body which is loosely received within the clean-out branch. The sizing of the hollow float to fit loosely within the clean-out branch and, the open ended construction of the same are for the purpose of rendering the float relatively insensitive to transient back up flows within the access branch such as might be occasioned by the simultaneous drainage of a large number of plumbing facilities. The guide stem by which the float element is suspended is supported for vertical sliding movement, through oversize openings, at widely spaced points along the vertical length thereof to maintain the guide stem substantially vertical so that the likelihood of binding by virtue of applied bending moments is greatly reduced.

The upper end of the float guide stem carries an electrical contact which is normally spaced below a similar contact on the underside of the closure plug so that elevation of the float and its guide stem completes an appropriate circuit through the contacts to sound an adjacent and/or remote alarm. In this latter connection, it is always desirable that the building occupants be notified of an impending back flow and, in many cases, the circuit will alert a central station as through a direct circuit or any conventional remote signalling system to initiate the dispatch of maintenance personnel who can then clear the obstruction through the same access branch in which the sensor assembly is mounted.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic illustration of a cleaning operation being conducted upon a main sewage disposal line with parts of a building serviced thereby being shown in sections;

FIG. 2 is a cross-sectional view taken through the sensor assembly of the present invention as it would appear when installed in the access branch of FIG. I; and

FIG. 3 is a view similar to FIG. 2 illustrating a method of adjusting the vertical position of the float element.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1 is illustrated the lower of a plurality of plumbing fixtures adapted to drain through the plumbing system network 12 of building 14 into a subterranean lateral sewage disposal line 16 for delivery to a sewer main (not shown) typically located beneath an adjacent public easement. A branched fitting 18 having access branch 20 through which conventional cleaning equipment such as a rotary tool 22 may be inserted is conventionally installed when the lateral sewage disposal line is laid down. The upper end of access branch 20 extends substantially to ground level at a location exterior of building 14 for ready access thereto by maintenance personnel as schematically indicated in FIG. I.

A unit handled sensor assembly 24, which includes a clean-out access closure plug assembly 26 adapted to close the upper end of branch 20 in substitution for the conventional closure plug, is adapted for unit handled removal from branch 20 during a cleaning operation as indicated in FIG. 1. Following the cleaning operation, the sensor assembly is reinstalled with clean-out branch 20 as illustrated in FIG. 2.

Sensor assembly 24 includes, in addition to plug assembly 26, a suspension bracket 28 mounted to the underside of plug assembly 26 through the intermediary of conductive spacers 30, such as conventional nuts or the like, and removable fasteners 32. Vertically aligned, oversize openings 34 in the upper and lower walls 36, 38 of suspension bracket 28 loosely receive electrically conductive float guide stem 40 to the lower end of which is secured an open ended hollow, insulated float 42. An electrical contact 44 having a greater diametral extent than openings 34 is secured to the upper end of guide stem 40 above upper wall 36. A second electrical contact 46 is secured to the undersurface ofthe plug assembly, vertically above contact 44, by an insulating potting compound 48 or the like. Contacts 44, 46 are in circuit with a suitable power source (not shown) and an alarm signal 50, such as a buzzer or the like in building 14, through the intermediary of electrical connectors 52, one of the fasteners 32 and the electrically conductive guide stem 40 interconnected with a fastener 32 through a branch lead 54 and terminal connector 56. Connectors 52 extend through an opening 58 in plug assembly 26 prior to their respective direct connections to fasteners 32 and contact 46. The primary purpose in the particular illustrated connection of one connector 52 to guide stem 40 via branch lead 54 is to insure that connector 54 is grounded via fastener 32 and clean-out branch 20. Additionally, it will be apparent that when sensor assembly 24 is removed from branch 20, as in FIG. I, the terminal 56 and branch lead 54 are directly accessible through the open framework defined by suspension bracket 28 for ready replacement of branch line 54 as the same may wear by virtue of the corrosive environment and the flexing movement undergone thereby.

The vertical spacing between bracket walls 36, 38 is substantial in order to preclude binding of the guide stem as it may tend to tilt within the oversize openings 34.

Referring again to FIG. 1, and assuming the sensor installed condition of FIG. 2, it will be seen that the presence of obstruction 60 will cause drainage from a plumbing facility in building 14 to back up. So long as the necessary vertical movement of float 42 to close contacts 44, 46 lies at a level below that of the lowest plumbing facility 10, the alarm will be sounded before sewage back up into the facility takes place. To this end it is apparent that means must be provided for adjusting the null position of float 42 to accommodate terrain elevational differences as among various sites. In order to sound an alarm at the earliest possible time consistent with the avoidance of spuriously generated signals as might occur if the lower position of the float extended downwardly into the main sewage disposal line itself; it is desirable to freely suspend the lower end of the float as near to the peripheral confines of lateral disposal line 16 as practicable taking into account the usual curvature in branch line 20. Relatively small vertical adjustments may be made in the field ofa substitution of different size spacers 30 while coarse adjustments are effected in the manner illustrated in FIG. 3. Thus, for coarse adjustments, float 42 is removed from guide stem 40 as by unscrewing and a second guide stem 62, having an internally threaded socket portion similar to a like threaded socket portion in float 42, is threaded thereonto. Float 42 is then screwed onto an externally threaded lower end of second guide stem 62 to thereby extend the suspension length of float 42.

The vertical spacing between the upper end of float 42 and the lower bracket wall 38 exceeds that between the contacts 44, 46 so that the necessary range of float movement before an alarm is sounded is defined by the vertical distance between the contacts in the null position of FIG. 2. A coarse adjustment of the type illustrated in FIG. 3 does not affect this range of movement since the vertical spacing of the contacts is not altered, however, a substitution of spacers 30 would affect the necessary actuating range. If the fine adjustment made by sapcer substitution is small, normally no alteration is required except to insure that the contacts may still close before the upper end of float 42 engages lower wall 38. If, however, larger spacer substitutions are required a longer guide stem may be substituted and a spacer (not shown) positioned around the upper end thereof between contact 44 and upper wall 36.

It is desirable to use a float rather than a pressure responsive sensor primarily because of its relative simplicity and wide range of permissible vertical adjustment as just described. The use of a float actuated sensor does, however, tend to be oversensitive to transient flow conditions such as might occur when an unusually large drainage may temporarily move into branch 20. To compensate for such transient flow conditions, the greatest diameter of float 42 is smaller than the internal diameter of branch at its point of suspension therein so that any fluid flow into branch 20 would have to be up to the vertical level at which float 42 becomes buoyant as opposed to an earlier piston-like lifting effect that would tend to occur if the float were of substantially the same size as the internal diameter of branch 20. The float may also be made less sensitive to transient flow levels within branch 20 by the open ended float construction shown in FIG. 2.

In operation, and assuming the presence of an obstruction 60, the sewage back up in lateral disposal line 16 will enter branch 18 and elevate float 42 to sound alarm 50. At this point in time the total volume of the building plumbing system network 12 is still available to accept inadvertent or emergency drainage. Following sounding of the alarm, the sensor assembly may be removed and the obstruction cleared after which time the sensor assembly is reinstalled as in the position of F IG. 2.

I claim:

1. ln a subterranean lateral sewage disposal line communicating a plurality of building, plumbing fixtures with a sewer main and having a clean-out branch, exterior of the building in which said plumbing fixtures are located, extending upwardly therefrom to terminate in an exterior access opening closed by a clean-out access plug, the improvement comprising; support means suspending a float from said access plug, within said cleanout branch, for limited vertical movement relative thereto between a lower position above the subterranean level of said main disposal line and an upper position below the level of the lowest of said plumbing fixtures; signalling means responsive to movement of said float to said upper position for indicating a back up of sewage in said lateral disposal line; said support means including a suspension bracket having vertically spaced upper and lower walls; a guide stem rigid with said float and extending upward therefrom through vertical guide means opening through said upper and lower bracket walls; said guide stem terminating at its upper end above said upper wall in a first contact member engageable with a portion of the upper surface of said upper wall surrounding said vertical guide means opening therethrough; releasable mounting means mounting said suspension bracket in spaced :relation to the undersurface of said access plug; a second contact member mounted on the undersurface of said plug vertically above said first contact member; and said signalling means connected in electrical circuit with said first and second contacts.

2. The combination of claim 1 wherein the vertical spacing between said upper and lower bracket walls is equal to a major fraction of the length of said guide stem for reducing bending moments applied thereto; and said releasable mounting means including removable spacers whereby the vertical spacing between said suspension bracket and plug may be adjusted.

3. The combination of claim 2 wherein said float comprises a hollow body having a circular cross-section whose major diameter is less than the internal diameter of said clean-out branch at all positions of vertical movement relative thereto.

4. The combination of claim 3 wherein said float is an open ended hollow body whose entire hollow interior is in open communication with the interior of said lateral sewage disposal line.

5. The combination of claim 2 wherein said suspension bracket is defined by an open framework including said upper and lower walls; said guide stem being electrically conductive; and terminal means, intermediate said upper and lower walls, interconnecting said guide stem in circuit with 'said signalling means.

6. The combination of claim 1 wherein said guide stem comprises a plurality of releasably interconnected stem elements for effecting coarse adjustments in the said first and second positions of said float.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2985187 *Mar 15, 1960May 23, 1961Odell A HamiltonSewer cleansing alarm
US3185789 *Sep 26, 1962May 25, 1965Lawrence Gunther PhilipFluid overflow switch apparatus
GB167359A * Title not available
GB189628611A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4398186 *May 27, 1981Aug 9, 1983Statz Ralph MSewer back up warning system
US4467156 *Jan 10, 1983Aug 21, 1984Ford Motor CompanyLiquid level sensor switch
US4694128 *Jul 7, 1986Sep 15, 1987Casco Products CorporationFloat switch construction for monitoring liquid levels
US4758700 *May 18, 1987Jul 19, 1988Casco Products CorporationSwitch construction employing contact having spaced-apart contact points
US4961068 *Jan 11, 1989Oct 2, 1990Hendricksen Curtis CDomestic sewer alarm
US4962370 *Apr 25, 1989Oct 9, 1990John BorrielloOff-center cap-level magnetic float sewer alarm
US4973950 *Dec 4, 1989Nov 27, 1990Robert TourtillottSewer blockage alarm
US5006833 *Jul 25, 1989Apr 9, 1991Cdf, Inc.Sewer line restriction alarm placed in clean out plug
US5125247 *Dec 31, 1990Jun 30, 1992Mills Stephen DWashing machine overflow prevention device signal quality indicator
US5699049 *Jun 28, 1995Dec 16, 1997Difiore; DanteMonitoring system for non-pressurized conduit
US8059004 *Jan 7, 2009Nov 15, 2011Eric JamesDrain blockage responsive alarm system
US9123230Aug 13, 2013Sep 1, 2015Frank T. RogersSewer backup alarm
US9127445Nov 19, 2013Sep 8, 2015Tristram C. DunnSewer alarm apparatus with probe extending through a monitored pipe
US9217577 *Feb 6, 2015Dec 22, 2015Msd Research, Inc.Drain line access device with interior overflow safety switch
US20100171623 *Jan 7, 2009Jul 8, 2010Eric JamesDrain blockage responsive alarm system
US20150153055 *Feb 6, 2015Jun 4, 2015Msd Research, Inc.Drain line access device with interior overflow safety switch
U.S. Classification340/608, 340/624
International ClassificationG01F23/30, G01F23/56
Cooperative ClassificationG01F23/56
European ClassificationG01F23/56