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RECOMMENDED PRACTICE FOR FLOW MEASUREMENT IN WASTEWATER TREATMENT PLANTS WITH VENTURI TUBES AND VENTURI NOZZLES
Citation:
Kulin, G. RECOMMENDED PRACTICE FOR FLOW MEASUREMENT IN WASTEWATER TREATMENT PLANTS WITH VENTURI TUBES AND VENTURI NOZZLES. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/2-84/185 (NTIS PB85121663), 1984.
Description:
Venturi tubes and venturi nozzles are suitable for in-plant flow measurement of raw influent, treated effluent, return activated sludge, certain digested sludges, and for air and gas flows. However, they are not generally recommended for measurement of raw primary sludge. For classical venturi tubes which operate under optimum prescribed conditions, the primary-element discharge coefficient is predictable to within a basic uncertainty of about 1 percent. For standard venturi nozzles this basic uncertainty ranges from about 1 percent to 2 percent. Errors in the secondary system must be considered in addition to estimate the uncertainty of the output measurement. However, non-standard tubes and/or installations may require an initial field calibration of the primary-element coefficient as well as the secondary system. The primary calibrations are described in section 11.3 and usually involve either volumetric or dilution methods, or comparison with a reference meter.