Valves are basically used in pumps and piping applications. Valves are made of various materials. Most valves are made of metals like iron, steel, bronze, cast iron etc. There are certain valves made of rubber. Thin rubber components like gaskets, seals and valves are used in several industrial products ranging from the gaskets used in pneumatic solenoids, kitchen food processors, tires, weatherproof electrical connectors, check valve to the valves used in oil filters and respirators and many other such products. Rubber valves are being used as nozzles on air splurging systems in hopper tanks, railroad cars, and silos to prevent packing or bridging of materials. They are also used on diffusers to help in aeration and aerobic digestion, and in sludge holding tanks so as to keep solids in suspension.