Principle: EMCO wet gas metering is based on the classical venturi tube according to ISO 5167-4 with single pressure tappings. A third tapping may be applied for liquid flow rate determination using the pressure loss ratio method.
The system consists of a classical venturi tube in a
metering section. Differential pressure transmitter(s), static pressure transmitter or multivariable transmitters, a thermowell and a temperature transmitter an instrument cabinet, a wet gas flow computer and an over reading correction algorithm and if required for liquid flow determination tracer dilution system.
The metering section shall be mounted in a horizontal pipe run with pressure tappings pointing upwards.
Length of in- and outlet pipe are not critical. An inlet length of 5 times inner pipe diameter and an outlet length of 2 times is sufficient.
Impulse lines from transmitters to meter tube shall be sloped.
Wet gas metering systems require period check of fluid composition to ensure reliable flow rate measurement.
The span of time between each check depends on required accuracy and how quickly the composition of the flow rate change.
EMCO Controls can provide the initial start-up of the system as well as periodic flow check on site.
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Element type
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Classical venturi tube, machined type
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Design standards
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ISO 5167-4, ISO/TR 15377, ASME MFC-3M, ASME MFC Report 19G-2008 Wet Gas Flow Metering Guideline ISO/TR 11583
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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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22Cr Duplex (standard), AISI 316, 25Cr Duplex
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Mounting style
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Flanges to ANSI B16.5 or hubs for clamp connection
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Pressure taps
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½”, ¾” or 1” flanges or hubs
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Temperature tab
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1½” flanged
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Inlet cone
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21 or 10,5°
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Outlet cone
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7-15°
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Accuracy
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1 % gas flow, 10% liquid flow
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