Bronze valve [broken link removed] is a metal alloy produced by blending copper and tin in various amounts, depending on the application.Bronze is made by smelting copper and tin together. When bronze is cast for use in statues, it contains between two and 20% tin, while bells use a higher percentage of tin: 15-20%.Bronze has several properties that make it valuable in industrial applications. The first is that the metal causes minimal friction, making it highly useful for machine parts and other applications that involve metal on metal contact, such as gears. Bronze is also non-sparking, so it is often used to make tools for use in combustible environments. The resonance of bronze also makes it ideal for use in casting bells.