Many nations, including the United States, have enacted legislation to prevent lead from entering drinking water. Lead is a heavy metal and considered extremely harmful to health. In 1986, the U.S. Environmental Protection Agency (EPA) amended the Safe Drinking Water Act (SDWA) to greatly reduce the amount of lead that could leach out into drinking water. This law required that plumbing components that come into contact with drinking water, traditionally lead-containing materials such as solder and brass, be reformulated. The amendment reduced the amount of lead allowed in solder to less than 0.2%, and to no more than 8% in brass plumbing components. In January 2011, the SDWA was further amended to reduce the amount of lead allowed in these brass components to 0.25%.
Manufacturers, distributors, and installers are now preparing to replace older brass plumbing supplies with the new, lead-free variety in time for the January 2014 deadline. However, the older brass still has value and is still being used in products outside of the United States. Thus a quick, reliable, nondestructive method to differentiate the two types of alloys from one another is needed.
NSF International, working closely with the EPA and the American National Standards Institute ( ANSI), developed the NSF/ANSI 372-201 standard for measuring the lead content of drinking water system components. This standard designates X-Ray Fluorescence (XRF), Optical Emission Spectroscopy (OES), and Scanning Electron Microscopy (SEM)/ Energy Dispersive Spectrometer (EDS) as acceptable measuring tools.
Optical Emission Spectroscopy OES works by vaporizing a small amount of the material and analyzing the emitted light spectrum to determine the elements present and their relative concentration. These systems are bulky, and burns from spark tests can create significant surface blemishes up to 10 mm in diameter.
Scanning Electron Microscopy with Energy Dispersive X-Ray Spectroscopy Scanning electron microscopes equipped with EDS detectors can analyze the elemental composition of metal and other substrates. High-energy electrons striking the sample cause it to emit characteristic x-rays. The detector can identify the elements in the substrate by analyzing the energy spectra of the collected x-rays. These systems must be operated under high vacuum and sample sizes and shapes are quite limited. Such an analysis can take several minutes per sample and requires a skilled operator.
XRF is a nondestructive testing technique that can analyze a metal sample in seconds with little to no need for sample preparation. Handheld XRF analyzers work on the same general principle as EDS, but they are portable, require no vacuum, and can perform an analysis in seconds.
When the analyzer is held next to the sample and the trigger is pulled, an x-ray beam is emitted from the analyzer. This x-ray beam excites the atoms in the sample, causing electrons to be ejected and then replaced by other electrons. This results in a series of characteristic x-ray emissions returning from the sample. Each of these characteristic x-rays has and energy signature unique to the element from which it was emitted. By capturing, classifying and counting these characteristic x-rays, the analyzer can determine which elements are present in the sample and the relative concentrations of each.
XRF analyzers are the ideal solution for tracking and maintaining separate inventories of leaded and non-leaded brass parts. Portable XRF Analyzers have long been the instruments of choice for lead detection and are ideal tools to help you comply with the new lead-free brass mandate. With analysis results available in seconds, XRF analyzers enable the incoming inspection of brass alloys and outgoing inspection of finished products, providing you with the peace of mind that your products meet the new regulations.
Learn more about quality controls in this Lead-Free Brass application summary.
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