The seal consists of a lid that is rotary-mounted to the filter container base (10, 100) and has a body (11, 110) with at least two stub pipes (1, 2) and an internal part (12, 120) attached to the body. In the internal part (12, 120) are formed circulation ducts (5, 6) positioned as an extension of the stub pipes (1, 2) in opened position, and at least one bypass duct (3, 30) connecting the stub pipes (1, 2) in closed position. The internal part (12, 120) is attached to the body (11, 110) using a rotary bayonet mount by rotating to closed position in which the stub pipes (1, 2) are connected by the bypass duct (3, 30), and the body (11, 110) together with the attached internal part (12, 120) is attached to the base (10, 100) using a rotate-and-lock bayonet mount. In closed position the internal part (12, 120) is attached to the base (10, 100) in a stationary manner using a longitudinal head joint formed on the joined elements, and the changing to opened position occurs by rotating the body (11, 110) in the rotate-and-lock bayonet mount.