Combined water meter

Abstract

An automatically acting switch valve for a combined water meter which has a main meter for measuring larger flows and a secondary meter for measuring smaller flows. The switch valve has a switch insert including a carrier with a central slide bolt fastened to it, a shut-off member displaceably guided on the bolt and urged into closed position by a spring, a sealing seat of greatly narrowed cross section provided with an elastic seal between the carrier and the shut-off member. An annular chamber receives the shut-off member and opens downstream. It has a cylindrical zone and an adjoining same a conically narrowing annular zone which terminates in a narrowed shut-off member retention step. The shut-off member has a disk-shaped rim the front part of which is contained, in the closed position of the valve, within the cylindrical zone of the annular chamber. The dimensions are so adapted to each other that the seal only frees the main-stream passage when the disk rim of the shut-off member moves up into the conically narrowed annular zone under the pressure of the water. Due to the construction of the invention, a weak, short restoring spring is required so that the switch valve can be made small and compact.