The classical venturi tube is one of the most tested and trusted flow meters on the market. Based on the ISO 5167-4 standard, it offers durable flow measurement with minimal pressure loss.
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Design and calculation standards
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ISO 5167-4, ASME MFC-3M
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Sizes
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DN 50 - DN 250, 2” - 10"
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Pressure rating
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PN 10 - 640, 150 - 2500 lbs, ISO PN 20 - 420
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β (d/D)
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Preferred range 0,4 < β < 0,75
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Material
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Carbon steel, AISI 316, Duplex, 254 SMO, other on request
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Mounting style
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Weld ends according to DN 2559 or ANSI B16.25. Flanges acc. to DIN or ANSI B16.5 standards (Greyloc Clamp connection available on request)
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Pressure taps
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Weld ends Ø 21.3 mm, 26.9 mm, thread connection 3/8", 1/2" BSP, 1/2" NPT, or flanged
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Tappings
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Single pressure tappings or 2x4 tappings each arranged with an external annular ring to equalize the pressure
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Outlet cone
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7-15°
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Accuracy
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1 % (acc. to ISO 5167)
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Pressure loss
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Depending on outlet cone, between 10-15% of the differential pressure measured
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Limits for Reynolds No
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2*10^5 < ReD < 2*10^6 according to ASME
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Shut-off valves
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Condensing chamber unit for steam flow
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The machined venturi tube must be installed in a straight cylindrical pipe without obstructions, with specific inner pipe diameter requirements. The required straight lengths vary based on beta values and the presence of bends or reducers. Full bore valves are recommended upstream, and the inner pipe wall must be clean and smooth. The Venturi tube should be centered carefully and connected to the differential pressure transmitter below it for most applications, except for gas flow. Safety devices must be in place to prevent pressure exceedance, and elevated temperatures should be avoided. Regular maintenance involves ensuring a deposit-free interior. Compliance with ISO 5167 and other standards is crucial for quality assurance.
Download the installation guide above for more detailed information.
