Valves and valve actuation – Valve – Materials
Patent
1996-05-30
1999-03-02
Chambers, A. Michael
Valves and valve actuation
Valve
Materials
137801, 137375, B03C 104
Patent
active
058760172
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to plumbing fixtures such as faucets providing potable water comprised of copper and copper alloys such as brass having the interior surfaces which come in contact with the water coated with tin.
BACKGROUND OF THE INVENTION
Plumbing fixtures having an interior lining or coating in order to prevent leaching or stripping of various metals into the water flowing through these fixtures are known. Thus, for example, German published patent application DE OS 35 15 718 describes a water spigot with a mixing and metering valve. In this fixture the interior bore of the water spigot is coated with plastic. This prevents leaching or washing-out of, for example, lead and zinc from brass fixtures or the stripping of copper from copper fixtures into the water. However, this plastic lining is very expensive to apply.
German patent DE PS 14 192 discloses a fixture body which has its interior tin-plated. However, the tin-plated interior is provided only in order to enable later casting of a lead lining on the inside of the metal body which is itself in contact with the liquid flowing therethrough.
German patent DE-PS 22 802 discloses valves, spigots, pump bodies or other machine parts having a protective coating of tin, among other materials, to protect against chemical attack by chemical agents. However, casting cores are inserted into the iron core to be protected which together with the iron core form a casting mold. This casting mold is lined with tin, thus creating a massive cast protective body of tin. Because of the thickness of the protective tin body, it cannot be employed with fixtures having threads.
It is also possible to utilize fixtures comprised of alloys, the components of which are considered to be physiologically safe. For example, bronze as a pure alloy of copper and tin. However, such alloys are relatively expensive.
Lead free brass alloys or alloys which prevent the leaching of tin due to the alloy's components are also known. However, such brass alloys exhibit disadvantageous machining properties such as forming machining tool clogging long chips upon machining.
Bismuth instead of lead can also be added to a brass alloy in order to maintain the requisite machining properties of the alloy. Also, arsenic or antimony can be used to combat so-called "de-zincing". However, the nature of such alloy is changed. This presents difficulties with recycling.
The present invention avoids the aforediscussed disadvantages and provides a plumbing fixture comprised of an inexpensive, conventional brass alloy wherein metals are not leached-out or stripped into the water flowing through the fixture.
SUMMARY OF THE INVENTION
The instant invention comprises a plumbing fixture such as a faucet for carrying drinking water comprised of copper and its alloys which is provided with an interior lining or coating comprised of tin. The alloys of copper of which the plumbing fixture is fabricated include those including zinc and lead, e.g., brass.
The tin lining or coating is quite thin, having a thickness of about 2 to about 4 .mu.m. The tin coating or layer is applied to at least the interior surfaces of the fixture, including the threads. The tin coating or lining is applied chemically from a liquid chemical tin coating bath. Thus, water flowing through the fixture comes in contact only with the relatively inert tin lining, thereby eliminating the problems of metals such as lead leaching into the drinking water. Furthermore, the total thickness of the tin coating of a maximum of 4 .mu.m is within the tolerance range of 0.025 to 0.05 mm of a customarily used screw thread based on the metric or inch system of the finished fixture. This means that the coated fixture does not require any additional working or finishing operations.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional view of a plumbing fixture; and
FIG. 2 is an enlarged partial sectional view of an interior thread of the fixture of FIG. 1 showing the tin coating.
DESCRIPTION OF THE PREFERRED EMBODIMENT
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REFERENCES:
patent: 3050608 (1962-08-01), Woody
patent: 3557824 (1971-01-01), Krehbiel
patent: 3630223 (1971-12-01), Schaverien
patent: 3733106 (1973-05-01), Rike et al.
patent: 4044993 (1977-08-01), Wheeler
patent: 4162680 (1979-07-01), Coch
patent: 5579808 (1996-12-01), Mikol et al.
Becker Walter
Reinecke Herbert
Chambers A. Michael
Kapustij Myron B.
Masco Corporation of Indiana
Redman Leon E.
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