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.
2
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
1
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
3
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
4
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
5
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
6
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
7
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
8
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
40
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.
11
5,632,825
12
* * * * *
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