What Does NSF 61 9 Mean On Top Of Faucet Copper Pipe?
At present, the domestic industry manufactures faucets with main materials including brass, stainless steel, plastic, etc. The vast majority of sales in the developed markets of Europe and the United States are copper taps, China, as the world’s largest exporter of taps, most of the export taps are copper taps. The main materials of copper faucets are copper and zinc, commonly known as brass. A small amount of lead is added to the brass during the machining process to improve the cutting performance of the brass. If no lead is added at all, the faucet will not only be difficult to cut, poor forging performance and other problems, even if the finished product, it will also lead to cracking due to poor stress corrosion resistance
Lead is a heavy metal that is harmful to human health, but mainstream faucets in developed countries in Europe and America are made of brass, and copper has not been replaced by other materials. This is because the precipitation of lead is limited by product standards to a certain value and is considered safe. For example, the North American faucet toxicity test standard, NSF/ANSI61-2012, requires that lead precipitation not exceed 5 μg to be considered safe.
Therefore, in view of the health hazards caused by heavy metal precipitation, the National Sanitation Foundation (NSF) conducted in-depth research and analysis of heavy metal precipitation in products in contact with drinking water, prepared the test standard NSF/ANSI61, developed detailed test methods and limit values requirements, and has become the authoritative toxicity test standard for drinking water contact materials in North America. The standard is widely accepted in some countries and regions, including China, for the evaluation of heavy metal precipitation from taps by direct or indirect reference.
2.1 Introduction to the standard “Drinking Water System Components – Health Effects”  was developed by the National Sanitation Foundation (NSF), since the first edition was issued in 1988, after several versions of the update, the current version is the 2012 version of the latest.NSF/ANSI 61-2012 standard covers products including piping systems (pipes and fittings), protective materials, sealing materials, valves, end products (such as taps, etc.).
2.2 NSF/ANSI& 61 heavy metal precipitation test process for water taps
The NSF/ANSI 61-2012 test section for faucets is Section 9, which is highly influential and authoritative in North America as a standard for evaluating heavy metal and organics leaching from faucet products from a system testing perspective. In Section 9, the faucet, as an end product, is by default exposed to the last 1 litre of water, i.e. it is this 1 litre of water that is affected by the precipitation of heavy metals and organisms.
The heavy metal precipitation test is carried out by taking three complete sets of taps and starting the pretreatment on Friday afternoon. First rinse the faucet with tap water and then fill it with soaking liquid. From Day 1 to Day 18, except Saturdays and Sundays, change the soaking solution every 2 hours from 9:00 to 17:00, 5 times a day. Extracts were collected at 9:00 on days 3, 4, 5, 10, 11, 12, 17, 18 and 19 for lead and 9:00 on day 19 for the remaining 13 heavy metals.
2.3 NSF/ANSI 61 Calculation of the Q value for taps
As precipitation of lead content is a dynamic process, the amount of precipitation varies from soaking period to soaking period. In order to quantify the average amount of lead precipitated at a given time, NSF applied statistical principles, calculated standardized concentrations using logarithmic mean and standard deviation, and finally calculated the statistical value Q for lead detection.
(1) Standardized concentration is calculated by the following formula: NF=N1×N2×CMV
(2) In the equation, N1=(SAF/SAL)VL/VF(static))N2VF(static)/VF(flowing)=1NSAF is the area of product overflow during actual use; Sal is the area of product immersion during testing; VL is the volume of water filled during testing; VF(static) is defined here as 1L. CMV is the cold water conditioning factor (= cold water filled volume/total water filled volume).
(3) Calculate the natural logarithm of the standardized concentration using the formula Yij=lnXij.
(4) Calculate the logarithmic mean for each of the 3 samples according to the following formula: Yi=(Yi3+Yi4+Yi5+Yi10+Yi11+Yi12+Yi17+Yi18+Yi19)/9
(5) Calculate the standard deviation of the logarithmic mean according to the following formula: (6) Calculate the Q value according to the following formula: where K is the constant value of the statistical parameter that depends on the size of the test sample, K = 2.6028 when there are 3 test samples.
2.6 NSF/ANSI61 heavy metal test results on faucet Intertek, as the first third-party testing organization in mainland China that can conduct NSF/ANSI61 testing, we summarize the experience of NSF/ANSI61 testing on faucets over the past 8 years and come to the following conclusions: (1) Lead content precipitation is dynamic, but the overall trend is gradually decreasing. (2) In general, heavy metal precipitation failure is mainly concentrated in the following heavy metals: lead, copper, arsenic, zinc, cadmium, etc. Statistics of the last 100 models of faucets NSF/ANSI61 test results, of which 92, or 92%, passed the test, failing 8, a failure rate of 8%. Of the 8 models that failed, the Q value of lead precipitation failed to account for 3, copper, arsenic, zinc, cadmium, chromium content failed to account for 1 each.
3.NSF/ANSI61 on the impact of the faucet industry due to the North American faucet testing standard ASMEA112.18.1/CSAB125.1 allows the maximum lead content of copper in water parts is 8%, but many manufacturing enterprises are concerned about the direct use of lead content of higher copper faucets made difficult to pass the NSF/ANSI61 test, so some enterprises will choose to use low lead copper or even lead-free copper faucets, but the process has changed, the technical difficulties and costs are higher.
Some enterprises will use the “lead washing” method to remove the lead from the water surface, the principle is to use the copper-lead melting point difference. The temperature of faucet casting is generally more than 1,000 degrees Celsius, and the melting point of lead is 327.5 degrees Celsius, so that the lead in the molding of the internal and external surfaces of the lead precipitation.
The lead content on the surface is much higher than on the inside. Washing lead before leaving the factory is to use the principle of chemical reaction process, with a high concentration of strong alkali solution to treat the sample, wash away the surface greasy material, and then strong acid treatment, then the lead in the copper faucet will quickly decompose away. In the NSF/ANSI61 test, the Q value of a faucet was 8.5μg before washing lead and 4.1μg after washing lead, with a significant decrease in Q value.
4. Summary combined with the earlier incident of lead in faucets, the focus of its controversy, mainly differences in testing methods. Some agencies adopt an internally developed approach, some adopt an industry association approach, and some adopt a recommended national standard approach, with different approaches and naturally different results. This leads to a lack of uniformity and asymmetry in media and public information. Therefore, as the new national standard is about to be implemented, we recommend that NSF/ANSI61 be introduced as a mandatory test method for faucets to test the precipitation of many heavy metals such as lead from a system perspective. The testing methods and requirements can be tailored to the current state of the industry