API TR 2577-2018 pdf download.Performance of Full-bore Vortex Meters for Measurement of Liquid Flows.
This technical report documents performance characteristics of several commercially available vortex meters for liquid flows. Although vortex meters are available in full-bore and reduced-bore designs, performance verification and characterization were limited to full-bore liquid vortex meters only, due to the inadequacy of test data available in the public domain for reduced-bored designs and lack of funding to develop a field test database for hydrocarbon liquids. Vortex meter test results reported in this document are of nominal 2-in. (50-mm) and 4-in. (100-mm) meter sizes. Five vortex meter vendors participated in the laboratory and field tests with hydrocarbon liquid of 4-in. (100-mm) meters, while only three manufacturers participated in the 2-in. (50-mm) tests. Since the flow rate through 2-in. (50-mm) vortex meters is relatively low, its use in field trials with hydrocarbon fluids was not possible, as it would delay and limit the normal operation of the field meter. Therefore, 2-in. (50-mm) vortex meter tests were limited to performance verification at the laboratory test facility with water only. The baseline performance of each meter was established under controlled flowing conditions of the laboratory test facility, where the test fluid was water. Commercially available 4-in. (100-mm) vortex meters output may have a manufactured pulse, where the pulse output is used during proving of the meter to establish the meter factor and repeatability of the meter factor. Also, due to time variations of shed vortices that result from hydrodynamic instability and current limitations of the available sensor technology, the raw pulse signal of vortex meters require time averaging. The reference flow rate at the proving facility was established by a Small Volume Prover (SVP), also referred to as Captive Displacement Prover (CDP), because proving of field meters for hydrocarbon fluids was performed by portable proving systems that used SVP.
To achieve adequate statistical accuracy for the meter factor, vortex meters require a certain number of shedding cycles. Since shedding cycles are directly tied to total flow volume through the vortex meter, a flow volume that is greater than the volume between the detector switches of a SVP was needed. As the output of 4-in. (100-mm) liquid vortex meters generally apply a time-averaging technique to achieve repeatable vortex shedding frequency—which defines the flow rate output—the run time of a SVP used to calibrate 4-in. (100-mm) flowmeters, especially at high flow rates, was deemed inadequate. Therefore, the transfer proving technique was utilized to document the vortex meter performance. The minimum averaging time of the vortex meter proving run by the MM was defined as 60 seconds, which was mutually agreed upon by the vendors participating in the API sponsored vortex meter performance documentation tests. For a detailed discussion of the relationship between calibration and vortex shedding cycles, see ASME MFC 6-2013 Appendix A. Major vendors, who have vortex meters installed in the petroleum and petro-chemical industries across North America, were invited to participate in the API sponsored field performance experimental study of liquid vortex meters, but only five were involved in the research.