Gate valves use a handwheel or lever to raise and lower a gate within the valve body and control the flow of chemically compatible media within a system. General-purpose gate valves control the flow of compatible media in various commercial and industrial applications. Gate valves for potable water meet NSF/ANSI 61 requirements for handling drinking water. Gate valves for chemicals have wetted components (e.g., stems, valve body) meant to handle compatible corrosive media. Gate valves for the petroleum and gas industry are constructed of materials that meet API (American Petroleum Industry) standards for handling compatible petroleum products and gas. Gate valves for dry materials control flow of dry media, such as grains. Boiler blow-off gate valves drain tanks of debris and water.