Abstract
Most types of flowmeter are affected by flow disturbances caused by nearby pipe fittings. In the case of the vortex flowmeter, users currently have to rely on manufacturers' recommendations on minimum straight pipe lengths on either side of the meter as there are no relevant standards or codes of practice and little published experimental data. The paper presents some experimental results on the effects of upstream pipe roughness, single 90† bends, and pairs of 90† offset bends on the calibration in air of a vortex meter with a rectangular section bluff body. The results show that this particular vortex meter is sensitive to the roughness of the upstream pipework and required straight pipe lengths of about 55 diameters to avoid significant calibration changes caused by upstream bends.
Installation lengths can be reduced by placing a flow straightener upstream of a meter particularly if the straightener-meter package can be calibrated as a unit. This concept has been explored using a Mitsubishi flow straightener with the vortex meter and promising results have been obtained with a package of 10 diameters overall length.
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