device, fitted into a closed conduit, which consists of chambers of known volume and a mechanism driven by the flow, whereby these chambers are successively filled with water and then emptied, mõõtevahend, mis on paigaldatud suletud torusse, mis koosneb teadaoleva mahuga kambritest ja veevoo abil käitatavast mehanismist, mille abil need kambrid järjestikku veega täidetakse ja seejärel tühjendatakse