An open-top tank is also called an open-air tank, and is a type of tank that provides a layer of air above the stored powder or liquid. While a sealed tank is appropriate for storing hazardous chemicals, an open tank is suitable for storing non-volatile liquids. A bucket type hanging container is convenient for carrying around, and it comes with handle and dust protection lid. These products are commonly made from stainless steel. Some include silicone packing or a catch clip to prevent the contents from spilling, while others are tilted or come with a discharge port. An open-top tank is also used when inserting the stored materials from above the tank or when the contents need to be agitated like for brewing. Some products come with an agitator or temperature adjustment function. When mounting an expansion tank, mount it at the highest position of the circulation line.