Vega VEGAMET 861 - Page 48

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11 Applications and functions
VEGAMET 861 • 4 … 20 mA/HART
58866-EN-200401
be output via a corresponding number of pulses on the relay/current
output(owratepulse).Asamplingpulsecanalsobecongured.
Everyumegeneratesadierentlevelofbackwaterdependingonits
typeandversion.Thespecicationsofthefollowingumesareavail-
able in the instrument:
Predenedcurves
Aowmeasurementwiththesestandardcurvesisveryeasytoset
up,asnodimensionalinformationoftheumeisrequired.
•
Palmer-Bowlusume(Q=kxh
1.86
)
•
Venturi,trapezoidalweir,rectangularume(Q=kxh
1.5
)
•
V-Notch, triangular overfall (Q = k x h
2.5
)
Dimensions (ISO standard)
Whenselectingthesecurves,thedimensionsoftheumemustbe
known and entered via the assistant. As a result, the accuracy of the
owmeasurementishigherthanwiththespeciedcurves.
•
Rectangularume(ISO4359)
•
Trapezoidalume(ISO4359)
•
U-shapedume(ISO4359)
•
Triangular overfall thin-walled (ISO 1438)
•
Rectangularumethin-walled(ISO1438)
•
Rectangular weir broad crown (ISO 3846)
Flow formula
Iftheowformulaofyourumeisknown,youshouldselectthisop-
tion,astheaccuracyoftheowmeasurementishighesthere.
•
Flow formula: Q = k x h
exp
Manufacturerdenition
IfyouuseaParshallumefromthemanufacturerISCO,thisoption
mustbeselected.Thisgivesyouahighaccuracyofowmeasure-
mentwitheasyconguration.
•
ISCOParshallume
Flume