Abstract: Stretches of flowing water are doped with acrolein for the purpose of preventing excessive growth of plants and algae. In order to avoid transport of acrolein, acrolein is produced at the site where it is required by deacetalation of an acrolein acetal in the presence of an aqueous mineral acid. No electrical energy is necessary for this process. An acrolein acetal and an aqueous mineral acid solution are delivered from compression-proof storage tanks into a mixing chamber by the application of pressure from a pressure cylinder. The mixture is passed through a deacetalation reactor unit which includes a tubular reactor part and a container-shaped reactor part.

Abstract: Drilling device with force transmission from a hollow-cylindrical drive member to a tubular shank equipped with a drill bit wherein the drive member (3) is rotatably mounted in a housing (41), with the housing (41) being provided with a port (42) for a suction and/or flushing device. The interior of the drive member (3) is connected with the port (42) by way of holes in its wall and the flow path is provided with means (11, 27, 28, 29, 40, 453, 495, 496) for preventing clogging of the flow path.