Catalyzes the hydrolysis of levan with endo-type specificity. The products of levan hydrolysis are a mixture of fructose and a series of fructooligosaccharides up to 12-mer, with levantriose being the major oligosaccharide obtained. Is not active towards sucrose. Random hydrolysis of (2->6)-beta-D-fructofuranosidic linkages in (2->6)-beta-D-fructans (levans) containing more than 3 fructose units. Is completely inhibited by low concentrations of heavy metal ions, while Ca(2+) and Mg(2+) or chelating agents such as EDTA neither inhibit nor activate the enzyme to any significant extent. Optimum pH is about 5.5 at 50 degrees Celsius and shows an apparent shift towards higher pH values at higher temperatures. Belongs to the glycosyl hydrolase 32 family. Functional characterization has been done on a chimeric protein carrying at its C-terminus a fragment of the cloning vector instead of the levanase sequence. The exact location of the frameshift is not clear.