The present invention relates to plumbing devices, such as valves and fittings, which have a moderate to high silicon content and yet are capable of soldering to conduits to complete flow paths.
In recent years, the lead content in potable water has become of greater concern, particularly with the younger population. California has passed Assembly Bill 1953 which, beginning in the year 2010, limits the amount of lead content in plumbing devices for potable water to less that 0.25%. Pending federal legislation popularly referred to as the “lead-free drinking act of 2007”, proposes limiting the lead content in plumbing devices for potable water to less than 0.2%. Accordingly, conventional bronze plumbing devices, such as valves, fittings, and the like, which have a lead content significantly higher than (i.e., 4%-7%) would not meet the new proposed standards. In order to comply with the new standards, therefore, conventional bronze materials cannot be employed.
One alternative is to utilize a silicon bronze alloy which reduces the lead content to below the 0.2% level. Valves and fittings made of a silicon bronze alloy, however, require brazing as opposed to lead-free soldering when coupling to copper tubing and other fittings. Brazing requires a much higher temperature, typically provided by an acetylene torch or the like, which requires specialized skills of the tradesman. Also, the use of brazing temperatures can increase somewhat the potential for fire hazards, particularly at a construction site where numerous brazed joints are required. Accordingly, the use of silicon bronze does not appear upon initial investigation as a viable alternative.
It has been discovered that the use of low lead content silicon bronze, when electroplated in a galvanizing solution including a nickel and tin alloy, allows the plumbing fitting to be soldered utilizing conventional relatively low temperature lead-free solder, thereby providing plumbing fixtures which comply with future standards for lead-free potable water handling devices.
According to one embodiment of the invention, therefore, plumbing valves, fittings, and other potable water handling components are manufactured of silicon bronze having a lead content below 0.2%. Such components are subsequently electroplated with a galvanizing solution including saline or alkaline solutions containing nickel and tin. The resultant plated products can be soldered to the remaining copper components of a plumbing system using conventional lead-free solder. Other low lead metals, such as silicon brass, aluminum bronze, and other alloys generally not considered solderable, can be employed when treated according to the method of this invention.
These and other features, objects and advantages of the present invention will become apparent upon reading the following description thereof together with reference to the accompanying drawings.
Referring initially to
The fitting 20 of
The valve and fitting shown in
As seen in
Lead may be present at a maximum level of about 0.15% and preferably does not exist in the purest form of the C87800 alloy. Similarly, other silicon bronze alloys can also be employed, such as C87610, which preferably comprises copper at about 92%, silicon at about 4%, and zinc at about 4%. Normal impurities may include the following percentages of other metals at about the percentages indicated:
Lead may be present at less than 0.2% and preferably does not exist. The bodies and component parts of the valves and fittings are cast utilizing either a conventional green sand foundry casting process or utilizing a metal mold in a die casting machine in the process shown by block 30 in
Subsequent to the casting of the plumbing devices and any finishing to the cast part, such as burr or flash removal by machining (block 31,
During the plating process, the temperature can range between 50° and 80° C. with a current density of 1 to 4 A/dm2 at 0.3 to 1.5 volts. The plating solution is continuously filtered and circulated in a conventional manner and the pH is controlled utilizing an acid or base material, as necessary, to maintain the pH between 4.2 an 4.8. The resulting thickness of the coating 50 on the cast silicon bronze part is from about 0.2 microns to about 5 microns. Prior to the coating process, typically the plumbing devices are cleaned in a 10% to 20% solution of hydrochloric acid for a brief period of time, as is conventional, to assure the quality of the plating deposit on the body of the component being electroplated.
Subsequent to the manufacture of the plumbing devices, such as the valve 10 or fitting 20, they are employed in a plumbing circuit, such as the example partial circuit 60 shown in
Thus, with the system of the present invention, plumbing fittings such as valves, T's, elbows, Y's, and the like can employ substantially lead-free (i.e., less than about 0.2% or less) silicon bronze alloys which are electroplated to allow soldering utilizing low temperature lead-free solder to provide fittings which meet lead-free potable water drinking standards and yet provide ease of installation in a plumbing system. Although two examples of silicon bronze alloys have been presented herein, other silicon bronze alloys having lead content less than about 0.2% could likewise be employed. Also, other electroplating solutions which provide a solderable surface to the silicon bronze fittings may be employed. Although entire fittings will typically be immersed in a bath to electroplate the inner and outer surfaces, if desired, it may be possible to only electroplate those surfaces which will be soldered to connecting tubes or pipes by suitable masking of the components during the electroplating process. As a general proposition, however, such selective electroplating may be commercially impractical.
It will become apparent to those skilled in the art that various modifications to the preferred embodiment of the invention as described herein can be made without departing from the spirit or scope of the invention as defined by the appended claims.
This application claims priority under 35 U.S.C. § 119(e) on U.S. Provisional Application No. 60/945,391 entitled LOW LEAD SOLDERABLE PLUMBING DEVICES, filed on Jun. 21, 2007, by George J. Ballantyne, et al., the entire disclosure of which is incorporated herein by reference.
Number | Date | Country | |
---|---|---|---|
60945391 | Jun 2007 | US |