Knowledge Center

The recent incident of excessive lead in drinking water in Kai Ching Estate has raised public awareness of the lead content in everyday products. Many of the daily necessities, such as toys, kitchenware, bathroom appliances, and garment accessories, are die-cast products, so how to control and ensure that their lead content meets safety standards has become an important topic.

Die-cast zinc alloy products have a wide range of applications, but due to the zinc alloy have low chemical stability, many zinc alloy die-casting parts require electroplating treatment to enhance anti-corrosion performance, and improve the appearance and value of the product at the same time. The most common combination electroplating with copper/nickel/chromium and various colored plating. Common zinc alloy die casting plating products include faucets, zipper pulls, belt buckles, buttons, luggage buckles, toys, locks, lampshade decorations and door handles, etc.

The segregation phenomenon in the production process of zinc alloy ingots is caused by the different densities and solidification sequences of metal elements in the alloy and the different distribution of each element in the alloy ingot during solidification. This normal physical phenomenon does not affect the production of die casting, because after the alloy ingot is melted into a liquid state, the elements are evenly distributed. However, taking too few samples or improperly area them can skew the test results compared to laboratory tests. Therefore, when we test the composition of alloys, the correct sampling method becomes important. As a result, there is a set of standard sampling methods for zinc alloy ingots in the world, such as the British EN12060. Below, we compare the effects of different sampling methods on the test results, with the test results taken by the standard method as the criterion.

The Water Supplies Department (WSD) of Hong Kong has been providing drinking water in accordance with the World Health Organization (WHO) Guidelines for Drinking Water Quality, but since the incident of excessive lead in drinking water, the safety requirements of the Government, the practitioners and the public have increased significantly. After consulting experts, the WSD formulated the Plan for Enhancing Drinking Water Safety in Hong Kong on year 2017. In the past, the WSD placed more emphasis on testing the physical, chemical and bacteriological parameters of water samples at WSD's water supply points, but through this scheme, the material requirements and acceptance of newly installed drinking-water systems have been increased. The scheme consists of five sections, namely "Enhanced Drinking Water Standards and Water Quality Monitoring", "Enhanced Regulation of Internal Water Supply System", "Water Safety Plan", "Publicity and Public Education", and "Drinking Water Safety Regulatory System".