A check valve in particular for medical applications has a first hose connecting casing and a second hose connecting casing and a membrane disk configured between the two hose connecting casings. The liquid is explosively evaporated to remove the surface particle as part of the evaporation of the liquid. Venting control can be through use of a hydrophobic membrane or through use of float valves in the vent, and control of flow of liquid into the reservoir from the water supply line can be by a special float valve that allows high flow capacity at low pressures. The secondary projecting pieces are positioned between the primary projecting pieces that are adjacent to one another in the circumferential direction. A phosphor in the encapsulant emits a frequency in the visible spectrum different from the frequency emitted by the chip and in response to the wavelength emitted by the chip.