Abstract: An apparatus for automatically metering gas into liquid comprises a gas sly line including a gas pressure regulator (1), a gas flow meter (2), a gas flow governor (3), a vacuum check valve, and an ejector (5) connected to a supply line of the liquid being gasified, a liquid flow meter (9), and a control system (39). The gas flow governor (3) and the vacuum check valve are integrated in a single unit including a sealed chamber (11) whose two opposite walls are defined by diaphragms (12,13), a hollow cylinder (14) disposed between the diaphragms and having a central opening (17) through one its face end, a sleeve (19) with a closed end, mounted coaxially with the hollow cylinder centrally of a diaphragm (13), its closed end being fixedly connected with an output element (26) of the gas flow governor (3), and a needle valve with a valve with a valve seat (2) and a valve member including a stem (22) with a pointed tip (23 ) on its one end, extending axially of the hollow cylinder.

Abstract: A metering device for determining and controlling the content of a gas in a liquid, e.g. chlorine gas in water, comprises a pilot-operated check valve in a gas feed line, inserted between a vacuum diaphragm valve and an ejector. The metering device also comprises a concentration meter located on a main, a liquid flow meter, an electronic gas-to-liquid ratio setter correction controller coupled to a device for setting the concentration of the gas in the liquid, coupled to the concentration meter and coupled, via an actuating mechanism, to the gas-to-liquid ratio setter. Connected to the latter is an electronic gas-to-liquid flow ratio controller associated with signal distributors and an actuating mechanism of a gas flow controller. The invention permits the accuracy of metering a gas in a liquid, e.g. chlorine gas in drinking water, to be substantially enhanced, whereby the quality of drinking water is considerably improved.