Reference, Installation, and Operations Manual

Section 6: Meter operation

3-9000-743 Rev S

June 2013

 

 

 

Equation 6-19 Base-condition volumetric flow rate

 

Q

 

 

= Q

Pabs, f

⎞ ⎛ Tb

⎞ ⎛

Zb

 

 

 

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

-----

 

-----

 

 

 

Base

 

FlowPabs, b

⎠ ⎝ Tf

⎠ ⎝

Zf

where

 

 

 

 

 

 

 

 

 

QBase

=

“raw” volumetric flow rate (m3/h) (QMeter)

QFlow

=

flow-condition volumetric flow rate (m3/h) (QFlow)

Pabs, b

=

base-condition absolute pressure (MPaa) (PBase)

Pabs, f

=

flow-condition absolute pressure (MPaa)

 

=

(AbsFlowPressure) calculated as shown in Equation 6-23

Tb

base-condition temperature (K) (TBase)

Tf

=

flow-condition temperature (K) (FlowTemperature)

Zb

=

base-condition compressibility factor (ZBase)

Zf

=

flow-condition compressibility factor (ZFlow)

6.1.10Volume

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 m3 is stored as 12345 m3 for the integer portion and

0.750 m3 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:

Table 6-3 Volume Accumulation Data Points
Volumetric flow

 

Forward direction

 

Reverse direction

 

 

 

 

 

rate typeIntegerFraction

Integer

 

Fraction

 

 

 

 

 

 

 

 

Raw

PosVolUncorr

PosVolUncorrFrac

NegVolUncorr

 

NegVolUncorrFrac

 

 

 

 

 

 

Flow-condition

PosVolFlow

PosVolFlowFrac

NegVolFlow

 

NegVolFlowUncorr

 

 

 

 

 

 

Base-condition

PosVolBase

PosVolBaseFrac

NegVolBase

 

NegVolBaseUncorr

 

 

 

 

 

 

Volume

201