KROHNE Summit 8800 Vol 2 - Manual (Page 28)

28 www.krohne.com 08/2013 - MA SUMMIT 8800 Vol2 R02 en
SUMMIT 8800 METERING PRINCIPLES 03
3 .5 Meter corrections
3 .5 .1 Gas & steam
The meter provides a number of pulses/s. We would like to know the Volume flow rate e.g. m3/s.
For this need:
Pulse factor or impulse factor or meter factor
The factor provided by the manufacturer of the meter giving the number of pulses per volume of
gas e.g. Pulses/m3. This assumes a linear meter. This is configured in the meter section.
Linearisation/ error Curve
The errors in % obtained during calibration of a meter which are the corrections needed to lin-
earise the meter. So for each flow rate a different error is used. In between the given flow rates
a linear interpolation is used. For flow outside the operating range, extrapolation is used, except
when MID is chosen, then the error is fixed, and low and high flow is used.
Volume flow rate= Pulses per period*(1-Error)
Gross Volume= Pulses*(1-Error)
3 .5 .2 Liquid
The meter provides a number of pulses/s. We would like to know the Volume flow rate e.g.
gallons/s. For this there are three important corrections for the meter possible:
K-factor
The factor provided by the manufacturer of the meter or as a result of proving which is the num-
ber of pulses per volume of fluid e.g. Pulses/gallon.
For a linear meter only one factor can be given.
In case that the meter is not linear then a K-factor curve can be used. In this These factors are
obtained during calibration or prove of a meter which are the corrections needed to linearise the
meter. This is expressed by a variation of the K-factor over the specified flow range. So for each
flow rate a different K-factor is used. In between the given flow rates a linear interpolation is
used. For flow above maximum extrapolation is used.
Meter factor
The factor determined during proving to correct a fluid flowmeter for the ambient conditions by
shifting its curve. The factor is used to compensate for such conditions as liquid temperature
change and pressure shrinkage and is meter and product dependent. The meter factor should
be close to1.
Equation 2 Volume calculation with MF
Equation 3 Gross volume calculation with MF