Abstract: A method for operating a combustion unit (1), a fuel (6) being burned with an oxygen-containing carrier gas (7) in at least one combustion space (2) with the release of an exhaust gas flow (8), ambient air (10) being separated into a product gas (12) which is enriched with oxygen and into exhaust air (13) enriched with nitrogen, a gas flow (9) being separated from the exhaust gas flow (8) and returned to the combustion space (2), the returned gas flow (9) being mixed with a gas flow (12a) of the product gas (12) to form a carrier gas (7). The carrier gas (7) and fuel (6) are supplied separately to the combustion space (2). The argon concentration in the returned gas flow (9) and/or in the carrier gas (7) is measured.

Abstract: A washing device (18) designed for at least partial cleaning and/or care and/or disinfection of a human foot is presented and described. According to the invention, the washing device (18) has at least one plate-shaped base body (17) and at least one cleaning body (25) connected to the base body (17), the cleaning body (25) being designed for cleaning and/or care and/or disinfection of at least parts of the human foot, and the base body (17) being arranged on the ground.