Stock material or miscellaneous articles – Composite – Of epoxy ether
Reexamination Certificate
1999-08-24
2002-05-07
Dawson, Robert (Department: 1712)
Stock material or miscellaneous articles
Composite
Of epoxy ether
C428S413000, C427S386000
Reexamination Certificate
active
06383643
ABSTRACT:
TECHNICAL FIELD
The present invention relates to coatings for plumbing fixtures and components, such as water meter housings, which will help prevent the leaching of lead and other metals into water supplies.
DESCRIPTION OF THE BACKGROUND ART
Water supply systems are formed by numerous plumbing components including pipes and plumbing fixtures, faucets, valves, couplings and pumps, and further including water meters and their component parts, including water meter housings. Water meter housings have traditionally been made of brass or bronze alloys, either cast or wrought. Such alloys may include lead in amounts from one per cent to eight per cent by weight.
Lead has long been identified as a hazard to humans in certain quantities. To reduce exposure to lead, federal and state government agencies have issued regulations that set standards for acceptable levels of lead in drinking water and the amount of lead that can leach from plumbing fixtures. It is a goal of manufacturers of these products to reduce or eliminate the leaching of lead to the greatest extent possible. Several strategies have been employed by plumbing fixture manufacturers in response to this problem. For example, the amount of lead in the metals used in plumbing fixtures and water meter housings has been reduced to produce new low-lead alloys. The low-lead alloys have not always proved a satisfactory alternative, for several reasons. First, even though lead is present only in small amounts in the low lead alloys, the leaching of other metals may occur. Second, the new materials have not been tested enough to date to guarantee long term reliability. Third, these materials can be uneconomical for some applications.
Some leach-resistant coatings have been proposed, such as bismuth or tin nitrate, but they present a potential to leach their metals.
Plastic housings have been used in some water metering applications, but plastic is not suitable for all applications.
Various other materials have been tested for possible use as coatings for water meter housings, including water-born thermoset materials, UV-cured polymers, clear powder-coat epoxy materials, tin, copper and nickel plating materials and nylon. The metallic coatings tended to show pin-hole defects. The powder coat epoxy and nylon coatings became too thick in places. If a coating becomes too thick, it affects the fit between the housing or fixture and other parts to be assembled with it, and this could impair the accuracy of the meter.
A general object of the invention is to provide an improved barrier coating for water meter housings and other plumbing fixtures, in which the coating provides a barrier of protection against leaching of metals, including lead, from the housing material into water contacting the housing or plumbing fixture in use.
A further general object of the invention is to provide a barrier coating for materials currently in use for plumbing fixtures, so as to retain current foundry and manufacturing methods, reliability in the field and recycling value of current products in the field.
SUMMARY OF THE INVENTION
The invention relates to making a coated substrate having a coating comprising an epoxy resin, a curing agent and optionally, a pigment. The coating is preferably applied using cationic electrolytic methods, but could be applied using other methods, such as brushing or spraying. The coating of the present invention can be applied to substrate materials currently in use, so that new materials and new foundry practices do not have to be developed for new lead-free metals.
Substrates coated with coatings of the invention have exhibited no pin holes or other discontinuities compromising the barrier effect or longevity of the coating. The coating is effective in reducing metal extraction to levels significantly below ANSI/NSF Standard 61 limits, when the housing is assembled in its normal assembly. Coating adhesion and integrity are good. The coating can be applied with a resulting thickness that is sufficiently thin so that chamber insertion and sealing, register bayonet mounting, bottom bolt holes and other close tolerance portions of the housing are not rendered out of tolerance. The coating can be used to reach internal surfaces including underhangs, corners and channels. And, the coating is economical to apply in manufacture.
These and other objects of the present invention will become readily apparent upon further review of the following specification and the drawings which are incorporated herein and which describe and illustrate several preferred embodiments of the invention. Such embodiments are not, however, exhaustive of all possible embodiments, and therefore reference should be made to the claims which follow the description for the legal scope of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention is incorporated in a coated substrate, such a water meter housing. Such housings have a cylindrical body with pipe coupling extensions extending from opposite sides. A bottom cover may close an access opening to the body cavity, and is often made of the same metal as the main housing part. While the invention is described as being applied to a particular component, the invention is also applicable to other types of plumbing fixtures, including faucets, valves, couplings and pumps.
Preferred materials for water meter housings include alloy materials selected from a group of brasses and bronzes including the following specific examples:
UNS C84400
UNS C83600
Alternative materials have been proposed for water meter housings including the following specific examples:
UNS C87800
UNS C89520
C89833 (Federalloy I-836)
The composition of these alloy materials, with respect to constituents to be discussed herein is specified as follows:
Alloy No.
Cu (% wt.)
Sn
Pb
Zn
C83600
84.0-86.0
4.0-6.0
4.0-6.0
4.0-6.0
C84400
78.0-82.0
2.3-3.5
6.0-8.0
7.0-10.0
C87800
80.0-83.0
.25 max
.15 max
12.0-16.0
C89520
85.0-87.0
5.0-6.0
.25 max
4.0-6.0
C89833
87.0-91.0
4.0-6.0
.10 max
2.0-4.0
Alloy No.
Si (% wt.)
Bi
Se
C83600
.005 max
—
—
C84400
.005 max
—
—
C87800
3.8-4.2
—
—
C89520
.005 max
1.5-2.5
0.8-1.2
C89833
.005 max
1.7-2.7
—
These alloys also include other metals in small amounts, generally less than 1% by weight.
In all of these alloys the majority constituent is copper, which is present to at least 75% by weight. Alloy Nos. C83600 and C84400 are copper-tin-zinc alloys with some amount of lead. No. C87800 is silicon bronze with substantial zinc and silicon content, but with low lead content. No. C89520 is a copper-bismuth-selenium alloy with low lead content and No. C89833 is a copper-tin-zinc and bismuth alloy with low lead content.
Still other materials which are deemed suitable for application of the present invention include the following list of alloys:
UNS C87200
UNS C92200
UNS C89835
UNS C87400
UNS C92300
UNS C89325
UNS C87500
UNS C93200
UNS C89510
UNS C87600
UNS C93500
UNS C90300
UNS C93700
UNS C90500
UNS C93800
UNS C94700
UNS C83450
UNS C94800
UNS C84800
UNS C94900
UNS C89831
All of the above alloys have at least 75% copper by weight.
The invention provides for the application of a film coating, preferably by electrodeposition methods.
In the process of electrodeposition, the electrodes are placed in the aqueous bath dispersion. When current is passed between the anode and cathode, an adherent film of the electrodepositable composition will deposit as a substantially continuous film on the cathodes, in this case the parts to be coated. Electrodeposition is usually carried out with a voltage in a range from 50 to 500 volts. The coatings of the present invention can also be applied by methods other than electrodeposition such as brushing, dipping, flow coating, spraying or the like, but electrodeposition is preferred.
A conveyor carries the parts to be coated through an electrodeposition dip tank and through the rinse tanks. The main dip tank has two electrodes disposed in the tank, an anode (+) and a cathode (−). The negative potential is applied to the parts to be coated, rendering them a
Badger Meter Inc.
Dawson Robert
Feely Michael J
Quarles & Brady LLP
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