Справочник Пользователя для Emerson Process Management 3420

3-9000-743 Rev S

June 2013

where

6.1.10

Volume

The Daniel Mark III Ultrasonic Gas Flow Meter meter provides forward and reverse volume 
accumulators for each of the three volumetric flow rate values: raw, flow-condition (raw with 
expansion and/or profile correction), and base-condition. Each volume accumulator is actually 
stored as a data pair: (64-bit unsigned integer portion, 32-bit floating point fractional portion). 
For example, a volume of 12345.750 m

3

 is stored as 12345 m

3

 for the integer portion and 

0.750 m

3

 as the fractional portion. Note that while a volumetric flow rate can be positive 

(indicating forward flow) or negative (indicating reverse flow), the volume accumulators are 
always positive values.

The non-volatile volume accumulator data points are as listed in the table below:

=

“raw” volumetric flow rate (m

3

/h) (

QMeter)

=

flow-condition volumetric flow rate (m

3

/h) (

QFlow)

=

base-condition absolute pressure (MPaa) (

PBase)

=

flow-condition absolute pressure (MPaa) 
(

AbsFlowPressure) calculated as shown in 

=

base-condition temperature (K) (

TBase)

=

flow-condition temperature (K) (

FlowTemperature)

=

base-condition compressibility factor (

ZBase)

=

flow-condition compressibility factor (

ZFlow)

Raw

PosVolUncorr

PosVolUncorrFrac

NegVolUncorr

NegVolUncorrFrac

Flow-condition

PosVolFlow

PosVolFlowFrac

NegVolFlow

NegVolFlowUncorr

Base-condition

PosVolBase

PosVolBaseFrac

NegVolBase

NegVolBaseUncorr

,

,

---------------







 T

-----







 Z

-----









=

,

,