5,632,825 Apparatus and method for inhibiting the leaching of lead in water

Patent Number/Link:

5,632,825

May 27,1997

[11]

[45]

IIIIIIIIIIIIIIIIIIIIIIII~IIIIIIIIIIIIIIIIIIIII ~IIIIIIIIII

US005632825A

Patent Number:

Date of Patent:

United States Patent [19]

Coltrinari et aI.

[54] APPARATUS AND METHOD FOR

INHIBITING THE LEACHING OF LEAD IN

WATER

[75] Inventors: Enzo L. Coltrinari, Golden; Jerome P.

Downey, Parker; Wayne C. Hazen,

Denver; Paul B. Queneau, Golden, all

of Colo.

[73] Assignee: Technology Management Advisors

LLC, Englewood, Colo.

3,713,814

3,773,504

4,180,398

4,551,395

4,867,116

4,879,094

5,076,941

5,137,685

5,193,936

5,262,124

1/1973 Larsson 75/156.5

1111973 Niimi et aI 75/157.5

12/1979 Parikh 75/157.5

11/1985 lloyd 428/677

9/1989 de Freitas Coutos Rosa et aI. ...... 123/

188AA

11/1989 Rushton 4201476

12/1991 Boffardi et aI 2101753

8/1992 McDevitt et aI. . 4201477

3/1993 PaI et aI 105/128

1111993 Yaruaji et aI. .. 4201477

[21] Appl. No.: 601,238

[22] Filed: Feb. 14, 1996

Primary Examiner-Sarn Silverberg

Attorney, Agent, or Firm-8heridan Ross P.C.

Related U.S. Application Data [57] ABSTRACT

[62] Division of Ser. No. 253,746, Jun. 3, 1994, Pat. No. 5,544,

859.

[51] Int. CI.6 C23C 22/52

[52] U.S. CI 148/269; 427/394

[58] Field of Search 427/394; 148/269

[56] References Cited

U.S. P.iITENT DOCUMENTS

2,802,733 8/1957 Bungardt 75/156.5

A copper alloy plumbing fixture containing interdispersed

lead particles coated noncontinuously on a water contact

surface to resist the leaching of lead into potable water

systems. The leach resistant fixture is prepared by immersing

conventional copper alloys in a bismuth nitrate solution,

selectively and noncontinuously coating the lead dispersoid

particles on the water contact surface with bismuth. Tin may

be substituted for bismuth to obtain similar results.

12 Claims, 6 Drawing Sheets

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5,632,825

This is a divisional of application Ser. No. 081253,746, 5

filed Jun. 3, 1994, U.S. Pat. No. 5,544,859.

body piece having a conduit surface that defines a conduit

volume through which the flow of a fluid may be directed.

The body piece comprises a first solid phase, which is a

continuous phase, and a second solid phase of dispersoids

comprised of lead dispersed in the first solid phase. A

plurality of the dispersoids are present adjacent the conduit

surface of the solid body piece.

The apparatus further includes a surface coating at the

conduit surface which comprises multiple distinct occur10

rences of coating material. At least a portion the occurrences

being interposed between at least a portion of the conduit

volume and at least a portion of the plurality of dispersoids.

The invention further includes an article useful in fluid

storage and transportation with a composition comprising an

15 interior portion having a metal matrix comprising greater

than about fifty weight percent copper. The interior portion

does not have any exposed surface. The article additionally

has a perimeter portion integral with the interior portion and

an exposed surface that may be in contact with a fluid. The

perimeter portion has dispersoids comprising lead dispersed

throughout a metal matrix which comprises greater than

about fifty weight percent copper.

The article further includes a coating in the perimeter

portion comprised of a metal coating material. The coating

has a top side and a bottom side, the top side forming a part

of the exposed surface and the bottom side being adjacent to

at least one dispersoid in said perimeter portion. The coating

substantially physically separates the lead in at least one

dispersoid from the exposed surface.

The invention further includes a solid material useful in

water service. The material comprises an interior matrix

phase which comprises copper, an exterior surface, and a

dispersed phase of particles consisting essentially of lead.

The lead is dispersed in the interior matrix with a plurality

of the lead particles adjacent the exterior surface. The

material additionally has a noncontinuous coating material

at the exterior surface which substantially physically separates

the lead in at least a portion of the plurality of lead

40 particles from the exposed surface.

The invention further includes an article for use in fluid

containment and transportation. The article comprises a flow

directing piece shaped to provide a fluid flow conduit, the

flow directing piece having an exterior surface. The interior

45 surface includes a fluid contact surface adjacent the fluid

flow conduit. The apparatus further includes a perimeter

portion in the flow directing piece which comprises the

exterior surface. The perimeter portion extends to a depth

smaller than about 100 microns into the body portion from

50 the surface of the exterior portion. The perimeter portion

may comprise lead. The apparatus flow directing piece

further includes an interior portion which is surrounded by

the exterior portion, the interior portion comprising lead.

The flow directing piece further includes a lead leach

55 inhibitor, the perimeter portion having an average concentration

of lead leach inhibitor that is greater than the average

concentration of lead leach inhibitor in the interior portion.

The invention further includes a copper-based metal composition.

The composition comprises greater than about 50

60 weight percent copper, from about one weight percent to

about ten weight percent lead, and less than about 0.005

weight percent of a lead leach inhibitor metal selected from

the group consisting of bismuth or tin, and combinations

thereof.

65 The invention further includes a method for preparing the

surface of a copper-containing article. The article comprises

a solid continuous phase comprising copper and a solid

FIELD OF THE INVENTION

SUMMARY OF THE INVENTION

BACKGROUND OF THE INVENTION

APPARATUS AND METHOD FOR

INHffiITING THE LEACHING OF LEAD IN

WATER

This discovery is accomplished by an apparatus for conducting

the flow of a fluid. The apparatus comprises a solid

Potable water systems are comprised of numerous components

including pipe and plumbing fixtures such as

faucets, valves, couplings, and pumps which both store and

transport water. These components have traditionally been

made of copper-based cast and wrought alloys with lead 20

dispersed therein in amounts between 1-9% by weight. The

lead allows these components to be more easily machined

into a final product which has both a predetermined shape

yet acceptable strength and watertight properties.

The lead used to improve the machinability of these 25

copper alloy materials has been proven to be harmful to

humans when consumed as a result of the lead leaching into

potable water. This damage is particularly pronounced in

children with developing neural systems. To reduce the risk

of exposure to lead. federal and state governments now 30

regulate the lead content in potable water by requiring

reductions in the amount of lead which can leach from

plumbing fixtures. A variety of strategies have been developed

to address this problem.. For example, simply reducing

the amount of lead in plumbing fixtures has been attempted. 35

However, such low lead content alloys are difficult to

machine.

Another strategy is to develop specific alloys such as that

disclosed in U.S. Pat. No. 4,879,094 to Rushton. The patent

describes an alloy which contains 1.5-7% bismuth, 5-15%

zinc, about 1-12% tin and the balance copper. This copper

alloy is capable of being machined. but must be cast and not

wrought. This is undesirable since a wrought alloy may be

extruded or otherwise mechanically formed into shape. It is

thus not necessary to cast objects to a near finished shape.

Further, wrought alloy feed stock is more amenable to high

speed manufacturing techniques and generally has lower

associated fabrication costs than cast alloys.

A copper based machinable alloy with a reduced lead

content or which may be lead free was disclosed by McDivitt

in U.S. Pat. No. 5,137,685. This alloy contains from

about 30--58% by weight zinc. 0--5% weight of bismuth, and

the balance ofthe alloy being copper. This alloy is expensive

to produce, however, based both on the cost of the bismuth

as compared to lead, and further since the bismuth must be

thoroughly mixed within the matrix of the copper alloy

material.

Despite the developments made in the area of reduced

lead leaching into potable water systems, there remains a

need to provide a material which is less susceptible to

leaching lead into potable water systems, yet which utilizes

the inherent benefits of copper alloys that contain lead.

This invention generally relates to lead containing materials

and products which are resistant to leaching lead into

potable water systems used for human consumption and

methods for the production thereof.

5,632,825

noncontinuous phase of dispersoids comprising lead dispersed

in the continuous phase. The article has an exposed

surface, wherein the continuous phase and a plurality of the

dispersoids forms at least a part of the exposed surface. The

method includes covering at least a portion of the lead in the

plurality of dispersoids with a noncontinuous coating phase.

As the aforementioned embodiments of the invention

disclose, lead containing copper-based alloys may be effectively

treated to prevent lead from leaching into water

systems. This treatment may be done efficiently and in a cost

effective manner utilizing conventional alloys. Other objects

and advantages of the invention will become apparent upon

reading the following detailed description and appended

claims, and upon reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a cross-sectional view of a pipe or plumbing

fixture capable of storing or transporting potable water

or other fluids.

FIG. 2 is an expanded cross-sectional view depicting the

conduit surface, perimeter portion, first solid phase, second

solid phase. and non-continuous surface coating.

FIGS. 3-6 illustrate quantitative test data obtained from

experiments performed on treated and nontreated copper

alloy test fixtures.

It should be understood that the drawings are not to scale,

and that the invention is not necessarily limited to the

particular embodiments illustrated herein.

DEI'AlLED DESCRIPTION OF THE

PREFERRED EMBODIMENT

The present invention is used for conducting the flow of

fluids such as water, while inhibiting the leaching of lead

into the fluid. The invention may include pipes, valves,

faucets. pumps and other commonly known plumbing fixtures.

The materials typically used in the production of these

plumbing fixtures include copper alloys, such as brass,

which have lead dispersed throughout the alloy material.

The materials are characterized in that lead which is exposed

to the water transportation surface of the apparatus is

selectively coated with a non-continuous surface coating

which substantially precludes lead from leaching into the

water.

One embodiment of the present invention is an apparatus

for conducting the flow of fluid. The apparatus includes a

solid body piece 2 having a noncontinuous surface coating

12. The flow directing or solid body piece 2 is shaped such

that it has a conduit surface 4 which defines a conduit

volume 6. The conduit volume 6 is the space through which

the apparatus is designed to have fluid flow. For example, in

the instance where the apparatus is a pipe, the conduit

surface 4 is the inside surface of the pipe. which contacts

water flowing through the pipe on the fluid contact or

conduit surface 4.

The solid body piece 2 includes a first continuous solid

phase 8 and a second solid phase 10 of dispersoids within the

first continuous solid phase 8. For instance, in the case of a

brass pipe having lead dispersoids throughout the brass. the

brass is the first continuous solid phase 8 and the lead

constitutes the second solid phase of dispersoids 10.

The first continuous solid phase 8 is typically metal and

more typically comprises copper. For example, the first

continuous solid phase 8 can be a copper alloy and can

contain over 50% by weight of copper. Such copper alloys

can be brass including Cu/ZnlSi; Mn bronze; leaded Mn

bronze and a variety of bronzes including CulSn; CulSnIPb;

CulSnlNi; CulAl; and other high copper alloys containing

94-98.5 weight percent Cu and 0.02 weight percent lead.

The alloys typically include between about 50 weight per-

5 cent and about 98.5 weight percent Cu, more preferably

between about 53.5 weight percent and about 94 weight

percent Cu and more preferably between about 60 weight

percent and about 82 weight percent Cu. In a preferred

embodiment of the present invention, a continuous solid

body phase comprised of about 57%-82% copper, 0.2% tin,

10 7%-41% zinc, 2%-8% lead, and trace amounts of iron,

antimony, nickel, sulfur, phosphorous, aluminum and silicon

is used.

The second solid phase of dispersoids 10 comprise lead.

The lead dispersoids are dispersed in the first continuous

15 solid phase 8 and a plurality are adjacent the fluid contact or

conduit surface 4. Thus, while the lead dispersoids are

contained throughout the interior matrix of the first continuous

solid phase 8, some portion can be exposed on the fluid

contact or conduit surface 4. Therefore, untreated solid body

20 pieces 2 having lead exposed to fluids flowing throughout

the conduit volume 6 allow for the leaching of lead into the

fluid, which may contaminate the fluid. Typically, lead

dispersoids approximately comprise 1-9% by weight of the

solid body piece 2 and more typically 3-5%. In one

25 embodiment, the second solid phase of dispersoids 10 consists

essentially of lead. The plurality of lead dispersoids

allows the solid body piece 2 to be machined more easily

and allows for the use of wrought alloy feed stock rather

than cast alloy components. In addition to lead dispersoids,

30 the second solid phase of dispersoids 10 can include dispersoids

comprised of elements which can be the same as the

non-continuous surface coating 12, i.e., gold, palladium,

silver, platinum, tin and bismuth.

In accordance with the present invention, the apparatus

35 also includes a non-continuous surface coating 12 at the

conduit surface 4 which includes multiple distinct occurrences

of a coating material. The occurrences are intetposed

between at least a portion of the conduit volume 6 and at

least a portion of the lead dispersoids. In this manner, lead

40 dispersoids are impeded from leaching lead into fluids, such

as potable water, which flow through the conduit volume 6.

One characteristic of the coating material is that it is

effective as a coating of the dispersoids under normal use

conditions for normal product lifetimes. Such coating char-

45 acteristics are typified by the coatings and coating processes

discussed below.

The coating of the second solid phase of lead dispersoids

10 inhibits the leaching of lead into fluid which passes

through the conduit volume 6 and which otherwise would be

50 in contact with the second solid phase oflead dispersoids 10.

In a preferred embodiment of the present invention, at least

about 90% of the surface area of the second solid phase of

lead dispersoids 10 exposed on the conduit surface 4 are

covered by the non-continuous surface coating 12. In a more

55 preferred embodiment. at least about 95% of the second

solid phase of lead dispersoids 10 exposed on the conduit

surface 4 are covered by the noncontinuous surface coating

12 and in a most preferred embodiment 99%.

In accordance with the present invention, the noncontinu-

60 ous surface coating 12 can comprise any metal which is

more electropositive than lead. For example, the surface

coating can comprise a material selected from the group

consisting of bismuth, tin, gold, palladium, platinum and

silver. Preferably, the noncontinuous surface coating 12

65 comprises material selected from the group consisting of

bismuth and tin. or combinations thereof, and most

preferably, the coating comprises bismuth.

5,632,825

The non-continuous surface coating 12 typically has a

thickness no less than about 1.2 nanometers, with a preferred

thickness no less than about 4 nanometers. It should be

recognized, however, that any minimum thickness of noncontinuous

surface coating which provides adequate lead

coverage over the reasonable lifetime of the fixture at an

economical cost is acceptable. In a preferred embodiment of

the present invention the non-continuous surface coating 12

is comprised of bismuth with a thickness no less than about

4 nanometers.

In another embodiment of the apparatus of the present

invention, the solid body piece 2 of the apparatus comprises

a perimeter portion 14 which includes the conduit surface 4

and an interior portion 16 which is integral with the perimeter

portion 14. The interior portion 16 does not include the

conduit surface 4. In this embodiment, the interior portion

16 of the solid body piece 2 typically has a lower concentration

of coating material than the perimeter portion 14.

Thus, the coating material is not uniformly distributed

throughout the solid body piece 2, because typically the

coating material is applied directly to the conduit surface 4.

In another embodiment, the interior portion 16 of the body

piece is substantially free of coating material.

The perimeter portion 14 of the apparatus includes the

conduit surface 4 and extends from the conduit surface 4 into

the solid body piece 2 a distance less than about 100 microns

below the conduit surface 4, and more preferably extends

into the body piece a distance less than about 50 microns.

Thus, it should be understood that the coating material is not

only on the conduit surface 4, but can also extend into the

perimeter portion 14 of the apparatus some measurable

distance depending on the method of application of the

coating material to the apparatus.

The present invention also includes as another embodiment

an article useful for fluid storage and transportation.

This article may be used as a pipe, faucet, valve, pump or

other plumbing fixture or device for fluid storage and

transportation. The article includes an interior portion 16

having no surface exposed to the water or other fluid being

stored or transported throughout the article. The interior

portion 16 has a metal matrix typically comprising greater

than about 50 weight percent Cu, more preferably greater

than about 53.5 weight percent Cu, and even more preferably

greater than about 60 percent Cu. Other metals comprising

lead, tin, iron, silver, palladium, platinum, zinc and

bismuth may make up the remainder of the metal matrix of

the interior portion 16, depending on the alloy. The interior

portion 16 composition will usually comprise between about

1 and about 10 weight percent lead. Lead is typically present

as a dispersed solid phase in the matrix of the interior portion

16.

The interior portion 16 is integral to and adjacent to a

perimeter portion 14, which has an exposed surface that may

be in contact with a fluid being transported or held within the

article. For example, the exposed surface of the perimeter

portion 14 would be actually wetted by the fluid. The

perimeter portion 14 includes dispersoids of lead in a metal

matrix which typically comprises greater than about 50

weight percent of copper. Other metals such as lead, zinc, tin

and iron may additionally be included in the metal matrix in

the form of a copper alloy.

The article of the present invention further includes a

coating or lead leach inhibitor comprising a metal coating

material in the perimeter portion 14, the coating having both

a top side and bottom side. The top side of the coating forms

part of the exposed conduit surface 4 while the bottom side

is adjacent and overlaps at least one lead dispersoid in the

perimeter portion 14. The coating thus substantially physically

separates any such lead dispersoids from the exposure

to water. This separation effectively prevents lead from

5 leaching into water stored or carried in the article, since the

lead dispersoids are not in substantial contact with water at

the exposed surface. In a preferred embodiment, the coating

material substantially physically separates the coated lead

dispersoids for the reasonable expected lifetime of the

10 apparatus.

In a further aspect of the invention, the coating of the lead

dispersoids can be noncontinuous across the exposed conduit

surface 4. Thus, the coating is substantially consistent

with the random number and pattern of lead dispersoids

15 which are at the exposed surface. These separate occurrences

of coating material are adjacent to a corresponding

lead dispersoid in the perimeter portion 14 of the article, and

substantially physically separate the corresponding adjacent

lead dispersoid from the exposed conduit surface 4. As

20 referenced above, the noncontinuous coating preferably

covers a substantial portion of the lead dispersoids.

Another embodinlent of the present invention is a copperbased

material. In a preferred embodiment, the composition

comprises greater than about 50 weight percent copper, from

25 about 1 weight percent to about 10 weight percent lead, and

up to about 0.005 weight percent of a lead leach inhibitor

metal. The lead leach inhibitor metal is typically a metal

which is more electropositive than lead and preferably is

selected from the group consisting of bismuth, tin, gold,

30 palladium, platinum, silver and combinations thereof. More

preferably the lead leach inhibitor metal is bismuth.

In a preferred embodiment of the composition, the

copper-based metal composition comprises from about 7

35 weight percent to about 41 weight percent zinc. In a further

embodiment, the copper-based metal composition comprises

from about 0.2 to about 0.6 weight percent tin.

Another embodiment of the present invention is a method

for preparing the surface of a copper containing material to

40 impede the leaching of lead into water or other fluids. The

article may be, for instance a plumbing apparatus which

defines a fluid conduit volume 6 for storing or directing the

flow of fluids through the apparatus. The plumbing apparatus

may include, but is not limited to, pipes, valves, faucets,

45 fittings, and other fixtures commonly known in the art. The

composition and structural aspects of the article, which

typically includes copper, are the same as that of the

apparatus and articles, as broadly described above, but

without the coating material or lead leach inhibitor.

50 The process includes providing the article and covering at

least a portion of the lead in the plurality of dispersoids with

a noncontinuous surface coating phase 12. Thus, the method

can include preferentially covering the dispersoids and leaving

the continuous phase at the exposed conduit surface 4 of

55 the article substantially uncovered by the coating phase. This

method of selectively covering substantially reduces the

amount and cost of coating material required to effectively

coat the lead dispersoids exposed on the exposed surface as

compared to a continuous coating process. For example, in

60 a continuous coating process, the entire surface exposed to

fluid is coated, including both the lead dispersoids and

non-lead alloys. This continuous coating may be more

expensive since a large non-lead surface area is coated

unnecessarily. In a preferred embodinlent of the invention,

65 typically at least about 90% of the lead dispersoids present

at the exposed surface are covered, more preferably about

95% and most preferably 99%. Further, the continuous

5,632,825

phase of the exposed surface should remain substantially

uncovered with no more than about 20% covered by the

coating phase, more preferably less than about 10% covered

by the coating phase, and most preferably less than about 1%

covered by the coating phase. 5

The step of covering the dispersoids can comprise removing

a layer of a portion of the plurality of dispersoids from

the exposed conduit surface 4 to a depth extending into the

material and below the exposed surface. For example, the

step of removing can be a chemical substitution reaction to 10

substitute a layer of the coating material, such as bismuth,

for the layer of lead from an exposed dispersoid.

The layer of lead dispersoids removed typically extends a

depth of about 10 microns from the exposed conduit surface

4 into the solid continuous phase, and more preferably about 15

5 microns. As the layer of a portion of the plurality of

dispersoids is removed, at least a portion of the removed

layer is replaced with the coating material. The noncontinuous

coating phase is typically comprised of bismuth, tin,

gold, palladium, platinum, silver, or combinations thereof. 20

Preferably, the coating material is comprised of bismuth.

In a preferred embodiment of the present method, the step

of covering typically comprises contacting the clean,

exposed conduit surface 4 of the material with a solution

having dissolved therein a metal selected from the group 25

consisting of bismuth, tin, gold, palladium, platinum or

silver and combinations thereof. The concentration of the

metal in solution will depend upon the choice of salts and is

typically between about 0.25 gil to 2.0 gil, and more

preferably between about 1.0 gil and 1.5 gil. The metal is 30

typically provided in the solution in the form of a nitrate,

sulfate or other soluble salt.

The article can be treated to cover the article with a

coating phase by immersion in the solution for a sufficient 35

time to adequately coat the article. It will be noted that the

process is most efficiently conducted by minimizing the

amount of time the article is contacting with the solution.

The temperature of the treating solution is typically about

60° C., although the temperature of the solution can range 40

from about 15° C. to just below the boiling point of the

solution. Wide variations in the temperature of the treating

solution during treatment are unfavorable, however.

By use of the apparatus, articles or methods of the present

invention, the leaching of lead from plumbing fixtures into 45

potable water systems is significantly reduced. The effectiveness

of the present invention can be quantitatively measured

in various ways. For example, as noted above, the

percent coverage by a coating material or lead leach inhibitor

of lead dispersoids exposed on the surface of a fluid 50

conduit can be measured, for example by electron microscopic

techniques. In addition, the effectiveness of the

present invention in reduction of lead leaching into water

can be quantitatively measured by tests which measure the

amount of lead in water which has been allowed to stand in 55

contact with a fixture under standardized conditions. For

example, one standardized procedure has been established

by the National Sanitation Foundation and is known as the

National Sanitation Foundation 61 ("NSF-6l") procedures.

More specifically. Section 9 of the NSF-61 publication 60

discusses the procedure for testing mechanical plumbing

devices and components.

The NSF-6l standardized procedure requires the triplicate

testing of mechanical plumbing fixtures, wherein samples

are rinsed with tap water at room temperatures, then filled 65

with water at various temperatures for periods of time up to

90 days. The contaminant level of lead which has leached

into the water from the fixture is then quantitatively measured

to gauge the leach resistance characteristics of the

particular plumbing apparatus or fixture. This procedure is

discussed in detail below in the Example section.

As an example of the effectiveness of the disclosed

invention, untreated wrought brass alloys normally obtain a

NSF-61 score of about 10 micrograrnslliter when the alloy

is exposed to water for a period of 1 day. Thereafter, the

concentrations of lead fell within the range of 3-6

micrograms/liter during subsequent days of testing.

However, after treating these alloys by exposing the second

solid phase of lead dispersoids 10 with a lead leach inhibitor

as described herein for 30 minutes, a NSF-61 score typically

between about 1-2.5 micrograrnslliter was obtained after

exposing the fixture to water for a 1 day period. The lead

concentrations fell to less than 1 microgranIlliter during each

of the subsequent days of testing. Typically, after treatment

of copper-containing fixtures by the present invention, lead

leaching under standardized conditions can be reduced by

about 80 percent, more preferably by about 90 percent and

more preferably by about 95 percent.

Similarly, typical NSF-61 scores for untreated cast brass

ranges from about 50-55 micrograrnslliter after exposure to

water for 1 day, declining to about 38 micrograrnslliter on

day 2, and ranging from about 13-25 microgramslliter for

subsequent days of testing. After treatment of these cast

brass alloys in a lead leach inhibitor for 30 minutes, a

NSF-61 score of less than about 6 micrograrnslliter is

obtained after exposure to water for 1 day, and less than 2

micrograrnslliter in each of the subsequent days. Typically,

by treating cast copper-containing brass fixtures by the

present invention, lead leaching under standardized conditions

can be reduced by about 80 percent, more preferably

by about 90 percent and more preferably by about 95

percent.

The following experimental results are provided for purposes

of illustration and are not intended to limit the scope

of the invention.

EXAMPLES

Example 1

This example illustrates the treatment of various plumbing

fixtures according to the present invention. These treatments

were conducted using four types of wrought and cast

brass components commonly used in plumbing fixtures.

The first brass component was a single handle kitchen

("SHK") specimen containing both wrought and cast components.

The second and third components were comprised

of wrought brass and included a single handle lavatory

("SIlL") and double handle lavatory specimen ("DIlL").

The fourth component was a wide spout ("WSP") comprised

of cast brass.

The nominal composition of the wrought brass in the

tested specimens was comprised of 60.0-63.0 weight percent

copper, 2.5-3.7 weight percent lead and the remainder

zinc. The nominal composition of the cast brass in the tested

specimens was comprised of 78.0-82.0 weight percent

copper. 2.3-3.5 weight percent tin. 6.0-8.0 weight percent

lead, 7.0-10.0 weight percent zinc, 0.4 weight percent iron,

0.25 weight percent antimony, 1.0 weight percent nickel,

0.08 weight percent sulfur, 0.02 weight percent

phosphorous, 0.005 weight percent aluminum and 0.005

weight percent silicon.

Each type of fixture included three samples which were

treated according to the embodiments of the present inven5,632,825

9 10

On day 1, the fixtures are filled with the extraction water

for approximately 2 hours, then the water is dumped and the

process repeated for a total of 4 exposures. After dumping

the fourth water sample, the fixture is again filled with

extraction water and held in the fixture for approximately 16

hours.

On day 2, the water samples are collected and acidified

and then tested for lead content in accordance with NSF-61

procedures. Day 1 procedures are then repeated. For the

duration of the test, day 1 and day 2 procedures are repeated.

The tests may be extended with an exposure sequence of up

to 90 days, although only the contaminant levels present in

the overnight samples are used to evaluate lead-leaching.

The results of the NSF-61 leaching tests can be seen in

FIGS. 3-6, which depict the concentrations of lead leached

into the water in micrograrnslliter on the Y axis plotted

against the days of water exposure on the X axis. Although

a total of five fixtures were treated and subsequently tested

in accordance with NSF-61 procedures, only four figures

were generated since the SHK and KSP fixtures were

assembled prior to NSF-61 leaching tests. As the Figures

depict, the copper alloy specimens treated by the bismuth

nitrate solution are compared with non-treated samples.

As the test data indicates, the amount oflead leaching into

water from copper-alloy fixtures is significantly reduced

following the bismuth treatment. Typically, the amount of

lead leaching into water is reduced about 90 percent, and

more preferably reduced about 95 percent.

While the invention has been described in combination

with specific embodiments thereof, it is evident that many

alternatives, modifications and variations will be apparent to

those skilled in the art in light of the foregoing description.

Accordingly, it is intended to embrace all such alternatives,

35 modifications and variations as fall within the spirit and

broad scope of the appended claims.

What is claimed is:

1. A method for preparing a surface of a coppercontaining

article, said method comprising the steps of:

providing an article comprising a solid continuous phase

comprising copper and a solid noncontinuous phase of

dispersoids comprising lead dispersed in said continuous

phase, said article having an exposed surface, said

continuous phase and a plurality of said dispersoids

forming at least a part of said exposed surface; and

reacting at least a portion of said lead in said plurality of

dispersoids with a noncontinuous coating phase.

2. The method of claim 1, wherein said step of covering

comprises preferentially covering a portion of said plurality

50 of dispersoids and leaving said continuous phase at said

exposed surface substantially uncovered by said coating

phase.

3. The method of claim 1, wherein said step of covering

comprises removing a layer of a portion of said plurality of

55 dispersoids from said exposed surface to some depth into

said article below said exposed surface and replacing at least

a part of said removed layer with said coating phase.

4. The method of claim 1, wherein said continuous phase

comprises greater than about 50 weight percent copper.

5. The method of claim 1, wherein said dispersoids consist

essentially of lead.

6. The method of claim 1, wherein said noncontinuous

coating phase comprises bismuth.

7. The method of claim 1, wherein said noncontinuous

65 coating phase comprises tin.

8. The method of claim 1, wherein said step of covering

comprises contacting said exposed surface with a liquid

<0.001

0.001

0.005

0.008

0.047

Pb Content, gil

TABLE 1

Residual Accumulation of Lead in Solution

SOLUTION DESCRIPTION

VIrgin Solution

Solution From SHL Fixture

Solution From DHL Fixture

Solution from WSP Fixture

Solution from SHK Fixture

Example 2

This example illustrates The NSF-61 testing procedure

performed on the fixtures following treatment. This procedure

requires that the fixtures are flushed with tap water for

15 minutes, then rinsed with deionized water. The fixtures

are then prepared for testing by rinsing with 3 volumes of an

extraction water having a pH of 8.0±0.5, alkalinity of 500

ppm, dissolved inorganic carbonate of 122 ppm and 2 ppm

of free chlorine in reagent water.

Following the aforementioned fixture preparation, the 60

fixtures are exposed to extraction water at either a cold

temperature or hot temperature, depending on the intended

use of the fixture. The cold temperature is 23°±2° C.

(73.4°±3.6° F.), while the hot temperature is 6Qo±20 C.

(1400±3.6° F.) for domestic use or 82°±2° C. (1800±3.6° F.)

for commercial use. For the purposes of this test, each fixture

treated was tested with cold extraction water.

After removing the test fixtures from the bismuth nitrate

solution, the specimens were thoroughly rinsed with deion- 45

ized water and allowed to air dry before being subjected to

leachate testing. The lead leachate testing was performed

using the standardized NSF-61 leaching tests as discussed

below.

tion and subsequently tested according to NSF-61 standards

as described in Example 2.

The fixtures were prepared for treatment by rinsing each

component with acetone, followed by immersion in 0.1

normal (N) nitric acid (HN03) for 30 seconds. The fixtures 5

were subsequently rinsed with deionized water and allowed

to air dry prior to testing.

Each set of three fixtures was then immersed for a 30

minute period in a solution prepared by adding 4.64 gil of

bismuth nitrate (Bi(N03)3.5H20) and 15 gil of sodium 10

chloride (NaCI). The solution was prepared by dissolving

the salt in an agitated volume of deionized water, maintained

at 60° C.

The process tank consisted of a seven gallon polyvinyl

pail fitted with an agitator and baffles. The bismuth nitrate 15

and sodium chloride solution was circulated by allowing the

process tank to overflow into a reservoir, then pumping fluid

from the reservoir back into the process tank. The treatment

sequence of the fixtures was as follows: SHL, DHL, WSP

and SHK After the treatment of the HLfixture, two hundred 20

and fifty milliliters (rnl) of the bismuth nitrate solution were

added to the system to insure against bismuth depletion prior

to the treatment of the HHL fixture. Likewise, an additional

two hundred and fifty milliliters were added before the

treatment of the WSPand KSPfixture treatments, as was 181 25

rnl before the HKfixture treatment to ensure against bismuth

depletion. Treatment solution samples were drawn from the

virgin treatment solution and after the treatment of each

fixture to determine the amount of lead which leached from

the fixture into the treatment solution. The results of these 30

tests are tabulated below in Table 1.

5,632,825

* * * * *

second providing a coating comprising coating material

across at least a portion of said fluid contact surface,

said coating material selected from the group consisting

of bismuth, tin and combinations thereof.

10. The method of claim 9, wherein said matrix phase

comprises from about 50 weight percent to about 98.5

weight percent copper and from about 1 weight percent to

about 42 weight percent zinc.

11. The method of claim 9, wherein said matrix phase

10 comprises from about 50 weight percent to about 98.5

weight percent copper and from about 0 weight percent to

about 20 weight percent tin.

12. The method of claim 9, wherein said coating is

noncontinuous across said fluid contact surface.

solution having dissolved therein a metal selected from the

group consisting of bismuth, tin and combinations thereof.

9. A method for treating a plumbing apparatus, said

method comprising the steps of:

first providing an apparatus, said apparatus shaped so as 5

to structurally define a fluid conduit volume for directing

the flow of fluids through said apparatus, said

apparatus comprising a continuous matrix phase having

greater than about 50 weight percent copper and a

dispersed phase comprising lead;

said article having a fluid contact surface adjacent said

fluid conduit volume;

contacting said fluid contact surface with a treating material

comprising metal selected from the group consisting

of bismuth, tin and combinations thereof; and