Copper is currently the best material for faucet manufacturing. At present, whether it is in Europe, America or our country, most of the products sold in the market are copper faucets.
The main materials of copper faucets are copper and zinc, commonly known as brass. A small amount of lead needs to be added during the production of faucets to improve the cutting performance of brass.
If lead is not added to the faucet at all, not only will there be problems such as difficulty in cutting and poor forging performance, even if it is made into a finished product, it will also cause cracks due to poor stress corrosion resistance.
Copper faucets are inseparable from lead. Why are mainstream faucets in developed countries in Europe and the United States made of brass, and copper has not been replaced by other materials? The main reason is the antibacterial properties of copper.
According to historical records, Egypt began to use copper for wound disinfection, eye infections and burns, and drinking water disinfection before 2500 BC.
The United States EPA (Environmental Protection Agency) and many other world authoritative organizations have scientifically proven that antibacterial copper kills more than 99.9% of bacteria within two hours, making it the most effective contact surface material in the world. Any other material (such as silver ion coating or Stainless steel) can not be compared with it.
Copper can quickly kill super bacteria like MRSA and prevent the bacteria from producing antibodies. The inner wall of the copper faucet will not breed bacteria, which is an advantage that other materials (such as stainless steel and plastic) do not have.
With the mass production of low-lead copper (less than 0.25% lead) and the improvement of antibacterial performance, it is reasonable to believe that it will still be the best material for faucet manufacturing in the future.
1. The causes and hazards of lead in brass faucets
At present, the main material of domestic production faucets is brass HPb59, and its lead content is required to be less than 1.9%. Due to the lack of standards, in order to reduce costs and improve the cutting performance of brass.
Some manufacturers use brass with a lead content of 3% to 6%. The faucet casting temperature is generally 1053°C, and the melting point of lead is 327.5°C, so lead segregates on the inner and outer surfaces during forming.
The lead content on the surface is 3 to 5 times higher than the inside. The lead removal process can remove the lead on the surface, but the flowing water in the faucet will damage the lead-washed surface and form "corrosion".
The lead ions inside are exposed again, and the amount of lead precipitated increases again. To this end, the United States introduced low-lead copper to solve the problem of lead precipitation from the material.
Lead is the most harmful heavy metal in faucets. According to expert research, young children have poor body resistance, and their absorption rate of lead is more than 5 times that of adults.
And the sensitivity to lead is very strong, and the lead content of 50-60 micrograms in 100 ml of blood is enough to be poisoned. And this figure is only about 80-100 micrograms for adults. The total IQ, operational IQ, and language IQ of children with high blood lead are significantly lower than those of children with low blood lead.
2. Domestic and foreign lead limit standards and testing
There are two ways to express the lead content of faucets, one is the mass percentage of lead in the raw material, and the other is the number of micrograms of lead precipitated per liter of water after the immersion test or expressed by Q value.
Consumers need to be reminded that these are two different concepts, and that the lead value of raw materials meets the requirements does not necessarily mean that the leached lead value meets the requirements.
The most representative foreign country is NSF61 from the United States. The technical requirements and test methods of the domestic faucet JC/T1043-2007 "Limit for lead precipitation in water taps" are the same as those of NSF61.
JC/T1043 stipulates that there are at least 3 sets of samples of the same specification. During the test period, the water should be changed every 2 hours from Monday to Friday. Take the second, third, fourth, nineteenth, tenth, eleventh, sixteenth, seventeenth, and 18th soaking for 9 days. 16 hours of water for testing.
The JC/T1043 standard requires that the lead statistical value is less than 11ug (the new mandatory GB18145 standard is expected to be issued in 2014, and the Q value is 5ug).
That is to say, the Q value of the lead leaching amount is related to the volume of the product and the stability of the product, and is not a value that is directly tested with equipment by taking a water sample.
At present, the more authoritative testing institutions in China include the National Plumbing and Hardware Products Testing Center and the China Quality Certification Center Guangzhou CQC laboratory.
3. The development process and difficulties of low lead
Developed countries in Europe, the United States, and Japan started their research on the sanitation safety of faucets earlier. The United States began research on sanitation safety of faucets in the early 1970s.
In 1988, the National Sanitation Foundation NSF put forward the famous NSF61 "Health Effects of Drinking Water System Components", which put forward clear indicators for the safety indicators of faucets, especially the lead element requirement Q≤11ug.
The 2012 version of NSF61 reduces the value of lead to Q≤5ug. In 2010, California introduced the Low Lead Act AB1953, which stipulated the lead content requirements for faucets from a legal perspective.
The bill requires that "the weighted average lead content of the faucet that is in contact with drinking water does not exceed 0.25%", where the lead content refers to the weighted content, which is related to the product's water flow area.
The emphasis is on the compliance of the whole set of faucets. Leaded materials can be used for individual parts with small water passing areas. If the faucet is made of pure copper, the lead content of each component should be less than 0.25%.
In January 2014, the United States will implement the low-lead SB3874 standard. It is reported that some leading domestic companies have proposed to the National Standards Committee to formulate standards for low-lead copper materials, which will fill the gap in the domestic sanitary ware industry.
In my country, the current domestic research on low-lead copper is at the forefront of the world and has the world's largest low-lead copper manufacturing base.
However, there are still some difficulties in the implementation of low-lead faucets. The main reasons are three aspects: one is the negative treatment of small and medium-sized enterprises; the second is the lag of national standards; the third is the incomplete certification system.
Therefore, in order to accelerate the implementation of low-lead faucet and promote the upgrade of the entire industry, we call on relevant departments to issue national mandatory standards for faucets as soon as possible, improve the faucet-related certification system and strengthen the supervision of the faucet industry.
Whether it is in Europe, America or my country, low-lead faucet is an inevitable trend, and it also requires a process. I hope people can rationally view the problem of lead in faucets.
At present, lead-free copper and low-lead copper technologies have gradually matured. In the future, more consumers will be able to enjoy lead-free and low-lead faucets.