5,454,876
Oct. 3, 1995
[11]
[45]
111111111111111111111111111111111111111111111111111111111111111111111111111
US005454876A
Patent Number:
Downey Date of Patent:
United States Patent [19]
Primary Examiner-Scott Kastler
Attorney, Agent, or Firm-Dom, McEachran, Jambor &
Keating
[54] PROCESS FOR REDUCING LEAD
LEACHATE IN BRASS PLUMBING
COMPONENTS
[75] Inventor: Jerome P. Downey, Parker, Colo.
[73] Assignee: 21st Century Companies, Inc., Tyler,
Tex.
[21] Appl. No.: 285,007
[22] Filed: Aug. 2, 1994
[51] Int. CI.6 F23J 1/00
[52] U.S. CI 134/3; 134/22.1
[58] Field of Search 134/2, 3, 22.1,
134/22.11; 148/240,250 [57]
4,006,041
4,182,639
4,233,088
4,452,650
4,478,651
4,582,556
4,615,643
4,699,889
4,737,356
4,981,553
5,076,941
5,118,367
5,193,936
2/1977 Fabregas et al 148/6.16
111980 Pignocco et al 148/6.17
1111980 Kronstein 148/6.16
611984 Caule 148/31.5
1011984 Brock et al 148/31.5
411986 Butt et al. 156/525
1011986 Gouvenot 405/128
1011987 Sales et al 501/22
411988 O'Hara et al 423/659
111991 Tytgat et al 156/666
12/1991 Boffardi et al 210/753
6/1992 Starinshak 148/262
311993 Pal et al 4051128
ABSTRACT
[56] References Cited
U.S. PATENT DOCUMENTS
3,669,765 6/1972 Bradshaw et al 148/6.16
3,764,399 10/1973 Caule 148/6.15
3,779,842 12/1973 Grunwald et al 156/18
3,898,137 8/1975 Dueber et al 204143 G
3,905,907 9/1975 Shiga 252/79.4
3,940,303 2/1976 Caule : 148/31.5
3,950,193 4/1976 Caule 148/31.5
3,975,308 8/1976 Myles et al 2521520
A process for treating brass plumbing components to reduce
leachable lead when the component is subsequently exposed
to water includes exposing the brass component in an
aqueous solution containing a desired concentration of chloride
and pyrophosphate, with the chloride ion promoting the
dissolution of lead from the brass component and the
pyrophosphate ion preventing saturation of the solution with
lead insuring continuation of the dissolution process.
20 Claims, No Drawings
5,454,876
2
DESCRIPTION OF THE PREFERRED
EMBODIMENT
5
only economical and readily available chemicals and process
equipment
Another purpose of the invention is to render faucet
components in typical designs and typical materials acceptable
without perceptible deterioration of the cosmetic
appearance or function due to discoloration or excessive
removal of copper or zinc.
Another purpose of the invention is a process for treating
brass components which uses chloride and pyrophosphate
10 ions in aqueous solution.
Another purpose is a treatment process of the type
described in which the brass component is exposed to an
aqueous solution of chloride and pyrophosphate ions for a
15 predetermined time period, the solution being maintained at
predetermined temperature.
Another purpose is a treatment process as described in
which the aqueous treatment solution is re-circulated to
continually remove dissolved lead or insoluble lead precipi20
tate from the treatment tank..
Another purpose of the invention is to provide a brass
treatment process in which a brass component is exposed to
an aqueous solution containing a mixture of active ingredients
which both selectively dissolve metallic lead at an
25 accelerated rate while leaving the brass substantially unaffected
and also sequester the lead in solution such that the
solution reaction for lead does not naturally come to a halt
Another purpose of the invention is to provide a brass
treatment process which prevents lead from subsequently
30 leaching from the brass into water by creating a barrier about
any lead particles which remain on the brass.
Other purposes will appear in the ensuing specification
and claims.
The present invention is specifically directed to a process
for treating brass, and more specifically brass plumbing
components such as faucet bodies, shower heads and well
pumps, so as to reduce the leachable lead. The process
described will economically reduce leachable lead to an
amount which will be acceptable under the anticipated
standards to be set by the National Sanitation Foundation
and specifically the standard known as NSF-61. It is currently
anticipated that the NSF-61 standard will require the
concentration of lead found in solution ejected from the
faucet, to be on average, less than 11 micrograms per liter
50 (ug/L) overthe first 19 days of testing when the solution is
collected and the concentration calculated according to the
NSF-61 standard. This is an accumulated leachable lead
total and is basically determined in a protocol issued by the
NSF. Although there are a number of processes which may
55 treat brass to reduce the potential leachable lead, it is
essential that such a process be commercially viable in terms
of the cost and time involved in the treatment process so that
the faucets or other plumbing products which are treated will
continue to be viable in the marketplace.
The present invention is specifically directed to a process
in which the brass component, either a faucet body for single
handle or double handle use, is exposed to an aqueous
solution containing desired concentrations of chloride and
pyrophosphate. Sodium chloride and sodium pyrophosphate
65 are the preferred salts for introducing chloride and pyrophosphate
in solution although those skilled in the art will
understand that other chloride and pyrophosphate sources
THE FIELD OF THE INVENTION
SUMMARY OF THE INVENTION
1
PROCESS FOR REDUCING LEAD
LEACHATE IN BRASS PLUMBING
COMPONENTS
Leaded brass has been used in the manufacture of water
flow fixtures such as shower heads, faucets, tub spouts and
the like since such devices first came into modem use. The
Environmental Protection Agency has issued regulations
which limit the maximum quantity of lead that is permitted
to be leached into the water from such plumbing fixtures
during an overnight dwell or extensive period of non-use.
Most faucets presently in use will meet the maximum
leachable lead limits established by the EPA prior to 1993.
However, the EPA is now reducing the maximum permissible
limits, and it is widely anticipated that by the end of
1994, many faucet products currently in production will not
meet the revised limits. Consequently, most of the manufacturers
of water flow devices such as faucets are expending
substantial effort in the redesign of their products or their
manufacturing processes to meet the anticipated EPA guidelines
for leachable lead.
The EPA has delegated to the National Sanitation Foundation
responsibility to develop the protocol which will
determine the quantity of lead leaching into the potable
water supply from regulated devices such as faucets. It is
anticipated that the protocol will evaluate the lead leached
into the water supply during the first 19 days after installation,
and that on average faucets will be required to contribute
less than 11 micrograms per liter of lead per day to
the water sampled after filling and testing according to the
precisely defined procedure. The procedure will be defined
in a document known as the NSF-61 standard.
The present invention is directed to a process for treating 35
brass plumbing products in order to significantly reduce the
quantity of lead leached into the water. The process is
specifically directed toward reducing the total leachable lead
over the prescribed time period in the most cost effective
40 manner. Clearly, there are processes which will reduce the
leachable lead to amounts which meet the standard, but these
processes are so expensive or time consuming as to be
commercially unacceptable. The present invention provides
a process which is both commercial and one which will
45 provide a product which will meet or exceed the anticipated
NSF-6l standard for leachable lead.
The present invention relates to a process for treating
brass to reduce the quantity of lead which may subsequently
be leached from the brass when it is exposed to water.
The primary purpose of the invention is to provide a
process for the treatment of brass components which rapidly
removes at least a portion of the lead on the surface of the
brass, thus reducing the potential for lead to leach from the
brass when subsequently exposed to water.
Another purpose of the invention is to render typical
faucet designs made out of typical materials (most notably 60
CDA 360 brass and CDA 844 cast red brass) acceptable
under the anticipated NSF-61 standard after treatment times
of less than five minutes, which are relatively easy to
implement in a production facility.
Another purpose of the invention is to render faucet
components in typical designs and typical materials acceptable
under the NSF-61 standard after a treatment which uses
5,454,876
3
such as other polyphosphates and hydrochloric acid may
also be used. The invention will be described using sodium
chloride and sodium pyrophosphate, although it should not
be so limited. The brass component will be exposed to the
described solution, for example, by immersion or by flush- 5
ing.
The applicant herein has cause to be instituted numerous
tests of the described process in which the time of exposure,
the concentration of sodium chloride and sodium pyrophosphate
decahydrate and the temperature have all been varied. 10
Specifically, tests have established that brass plumbing components
immersed in an aqueous solution containing 15 gIL
of sodium chloride (a concentration of 0.26 molar chloride),
and 90 gIL of sodium pyrophosphate (a concentration of
0.20 molar pyrophosphate), at a temperature of 60° C. and
immersed at time intervals from 3.5 min. to 30 min. will 15
subsequently pass the NSF-61 leachable lead test. The tests
involved immersing brass faucet products for time periods
of 3.5 min., 7.5 min., 15 min. and 30 min. In each instance
the products all passed the NSF-61 test in that the amount of
lead leached over the 19-day test period was substantially 20
less than the anticipated standard of 11 ug of lead per liter
of water.
Further tests were run in which the treatment lasted for 3.5
min. and the following temperatures and concentrations 25
were utilized. In all instances the concentration of sodium
chloride was 15 gIL (a concentration of 0.26 molar chloride).
Brass faucet parts were immersed for 3.5 min. in the
following aqueous solutions, including the described sodium
chloride: 90 gIL of sodium pyrophosphate (a concentration 30
of 0.20 molar pyrophosphate) with the solution being maintained
at 35° c.; 90 gIL of sodium pyrophosphate (a concentration
of 0.20 molar pyrophosphate) with the solution
being maintained at 70° c.; 81 gIL of sodium pyrophosphate
(a concentration of 0.18 molar pyrophosphate) with the 35
aqueous solution being maintained at 60° C.; and 45 gIL of
sodium pyrophosphate (a concentration of 0.10 molar pyrophosphate)
with the aqueous solution being maintained at
60° C. In each of the above tests the accumulated total of
leachable lead over the 19-day test period prescribed in 40
NSF-61 was less than 11 uglL.
Additional tests were run in which the solution was
maintained at a temperature of 60° c., the immersion time
was 3.5 minutes, and the amounts of sodium chloride and
sodium pyrophosphate each varied from 25 gIL to 120 gIL 45
(a concentration of 0.42 molar to 2.1 molar chloride and 0.06
molar to 0.27 molar pyrophosphate). In each instance the
accumulated leachable lead, as per the NSF-61 protocol, was
less than 11 uglL.
Based on the tests described above, a brass faucet product 50
immersed in an aqueous solution of from 10 gIL to 120 gIL
of sodium chloride (a concentration of 0.17 molar chloride
to 2.1 molar chloride); sodium pyrophosphate in an amount
ranging from approximately 25 gIL to approximately 120
gIL (a concentration of 0.06 molar pyrophosphate to 0.27 55
molar pyrophosphate); an immersion time of from approximately
3.5 min. to approximately 30 min.; with the solution
maintained at a temperature offrom approximately 35° C. to
approximately 70° C., will result in a brass product which
will pass the NSF-611eachable lead protocol. The preferred 60
embodiment of the invention is to utilize a time period of 3.5
min., although it is anticipated that initial use of the invention
may have an immersion time of 5 min. The preferred
concentration is 15 gIL of sodium chloride (0.26 molar
chloride) and 90 gIL of sodium pyrophosphate (0.20 molar 65
pyrophosphate). It is preferred to maintain the aqueous
solution at a temperature of approximately 60° C. In addition
4
to the above-described parameters, it is preferred that the
aqueous solution be continuously circulated and be air
agitated for a constant infusion of oxygen. The solution pH
should be maintained in a range of 9.5 to 10.5, with a pH of
10 being preferred.
When the brass component is immersed in the described
aqueous solution, dissolved oxygen is converted to hydroxyl
ions by an electron accepting reduction reaction with water,
the electrons being provided by conversion of metallic lead
at the brass surface to lead ions in aqueous solution.
2Pb(s)+02(aq)+2H20(I)=2Pb
2
+(aq)+40H-(aq)
The chloride ions in solution accelerate the dissolution of
metallic lead. The pyrophosphate ions in solution chelate the
lead ions in a complex such as PbP2h2-, thus reducing the
chemical activity of the Pb2+ species and preventing the
above-described conversion of metallic lead from terminating.
In summary, five factors in the invention ensure that lead
is removed expeditiously:
1. Aeration of the solution is required to ensure an
adequate supply of dissolved oxygen, without which the
lead solution reaction set forth above would not occur.
2. Chloride ions are required to accelerate the rate of lead
dissolution.
3. Pyrophosphate ions are required to sequester the dissolved
lead in solution, thus preventing the above lead
solution reaction from reaching equilibrium.
4. Agitation of the solution is required to ensure that fresh
supplies of the reagents participating in the reaction rapidly
are brought to the reaction site at the faucet surface, and that
the products of reaction are rapidly removed.
5. A moderately elevated temperature is required to accelerate
the rate of reaction. However, too high a temperature
would reduce the availability of the required dissolved
oxygen.
His believed that with the pH in the described range of9.5
to 10.5 the surface lead will be dissolved as described. lithe
pH is acidic it is anticipated that a barrier of chloropyromorphite
or other lead phosphate compounds may form
about lead particles remaining on the brass.
Whereas the preferred form of the invention has been
shown and described herein, it should be realized that there
may be many modifications, substitutions and alterations
within the scope of the following claims.
The embodiments of the invention in which an exclusive
property or privilege is claimed are defined as follows:
1. A process for treating brass components to reduce
leachable lead when the component is subsequently exposed
to water, the process including:
(a) exposing the brass component to an aqueous solution
containing chloride in a concentration of from about
0.17 molar to about 2.1 molar and pyrophosphate in a
concentration of from about 0.06 molar to about 0.27
molar;
(b) the brass component remaining exposed to the aqueous
solution for a time period of from approximately
3.5 min. to approximately 30 min., with the temperature
of the aqueous solution being in the range of from
approximately 35° C. to approximately 70° C.
2. The process of claim 1 in which the concentration of
pyrophosphate is approximately 0.20 molar.
3. The process of claim 1 in which the concentration of
chloride is approximately 0.26 molar.
4. The process of claim 1 in which the time period of
immersion is from approximately 3.5 min. to approximately
7.5 min.
5,454,876
5 6
* * * * *
tration of from about 0.06 molar to about 0.27 molar.
14. The-process of claim 13 wherein the concentration of
pyrophosphate is approximately 0.20 molar.
15. The process of claim 10 wherein the brass component
remains exposed to the aqueous solution for a time period
ranging from approximately 3.5 min. to approximately 7.5
min.
16. The process of claim 13 wherein the concentration of
chloride is approximately 0.26 molar.
10 17. The process of claim 10 wherein the solution pH is
maintained from 9.5 to 10.5.
18. The process of claim 10 wherein the solution is
continually air agitated.
19. A process for treating brass components to reduce
leachable lead when the component is subsequently exposed
to water, the process including exposing the brass component
to an aqueous solution containing two kinds of active
species, one of the species promoting the dissolution of lead
from the brass component, with the other species sequestering
the dissolved lead in solution preventing the lead
solution reaction from reaching equilibrium.
20. The process of claim 19 wherein the solution is
aerated to provide dissolved oxygen to insure lead dissolution.
5. The process of claim 4 wherein the immersion time is
approximately 3.5 min.
6. The process of claim 1 wherein the solution is maintained
at a temperature of approximately 60° C.
7. The process of claim 1 wherein the solution pH is 5
maintained from 9.5 to 10.5.
8. The process of claim 7 wherein the solution pH is
maintained at about 10.
9. The process of claim 1 wherein the solution is continually
air agitated.
10. A process for treating brass components to reduce
leachable lead when the component is subsequently exposed
to water including exposing the brass component to an
aqueous solution containing concentrations of chloride and
pyrophosphate with the chloride ions promoting the disso- 15
lution of lead from the brass component and the pyrophosphate
ions sequestering the dissolved lead in solution, preventing
the lead solution reaction from reaching
equilibrium.
11. The process of claim 10 wherein the aqueous solution 20
is maintained at a temperature in the range of from approximately
35° C. to approximately 70° C.
12. The process of claim 11 wherein the aqueous solution
is maintained at a temperature of approximately 60° C.
13. The process of claim 10 wherein the aqueous solution 25
contains chloride in a concentration of from about 0.17
molar to about 2.1 molar and pyrophosphate in a concen-
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