| 摘要 |
A portable flow measurement system comprising a primary flow metering element and a secondary flow metering element is disclosed that will find application in metering irrigation water use, urban and rural storm water runoff, infiltration/inflow and wastewater flow rates. The primary element comprises a constriction in a closed conduit that produces pressures in the liquid flowing through it that are related to the rate of flow of the liquid. The constriction is preferably configured to cause essentially simultaneous filling of the constriction and the conduit upstream from it upon increasing flow rate and/or filling of the constriction and/or the upstream pipe before the modular limit is reached. The secondary element comprises a system for transmitting and sensing the pressures produced by the primary element, computing flow rates using the sensed pressure as a basis and storing the pressure data and/or the flow rate data. The pressure transmitting and sensing subassembly comprises a plurality of bubbler circuits, a plurality of mechanisms for controlling bubble release rate, at least one and preferable two differential pressure sensors, mechanisms for simultaneously applying the same pressure to the pressure side and the reference side of each differential pressure sensor and mechanisms for simultaneously applying a known differential pressure across each differential pressure sensor.
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