A combination pressure relief and vacuum relief valve for mounting on a storage tank is disclosed as having two vertical mounting connections of different elevations; a pressure relief valve mounted on one connection; and a vacuum relief valve mounted on the other connection such that said vacuum relief valve is higher in elevation than said pressure relief valve. The valve is sanitary for use in food and pharmaceutical production and storage and has highly polished surfaces to prevent processed material from sticking. The valve also includes special sloping surfaces in the body and connections to prevent processed material from standing in the valves. The pressure valve and vacuum valve may be removed separately or rotated separately for mounting. The combination valve may be attached on storage tanks or other vessels or conduits.