Improve flowmeter accuracy in cramped quarters
Improve flowmeter accuracy in cramped quarters Getting accurate pipeline flow measurements with an orifice meter requires that the flow be streamlined and stable upstream of the orifice. A long, straight section of pipe usually provides the required stability. However, in many cases, a complex piping configuration or cramped site conditions make such long, straight piping runs more of a luxury than the norm. Straightening devices such as honeycombs and vanes inserted upstream of the orifice can reduce the length of straight pipe required. But they provide only marginal improvements in measurement accuracy, and may still require significant straight pipe. A new flow-conditioning device developed by Cheng Fluid Systems, Inc. (Sunnyvale, Calif.) solves this problem. Combining rotation vanes with a 90-deg elbow, the Cheng Rotational Vane (CRV) produces stable flow immediately downstream of the elbow. A complex gas piping system at Bechtel Savannah River, Inc.`s Defense Waste Processing Facility (DWPF; Aiken, S.C.) contains several 90-deg, long-radius elbows. Located in a high-radiation zone, the pipe carries offgas from a glass melter. During operation, impulse lines transmit the pressure drop signal outside the radiation area, where a microprocessor converts it to a 4- to 20-mA signal. That signal is then sent to a remote monitoring and control system. With more »
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