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Calculates gas orifice plate and venturi flow
rate in accordance with ISO5167/BS1042 with drain hole calculation to
BS1042 Part 1 Section 1.2.
“Back Calculations” can also be performed to
calculate the beta ratio, orifice diameter, pipe diameter or
differential pressure for a given flow rate.
This calculation allows entry of temperature,
density and pressure at upstream and downstream locations including
recovered pressure. Density and temperature exponent may be calculated
from the isentropic exponent or entered by the user.
The pipe bore and orifice bore are corrected for
operating temperature. Differential pressure tappings may be selected
from Flange (1 inch spacing), Corner and D, D/2 taps. Liquid orifice
flow calculation can be selected disabling the Isentropic exponent and
setting the expansibility value to unity.
Calculation results include volume flow at line
and standard conditions, mass flow and energy flow. Pipe and orifice
bore diameter and beta ratio at line temperature are shown on the
report along with upstream pressure, temperature and density. Other
results include overall pressure loss, pressure ratio, expansion
factor, velocity of approach, Reynolds number and discharge
coefficient.
Additional calculations have been included for
orifice plate buckling and plate deflection uncertainty and a wet gas
calculation is provided for orifice plate and Venturi meters.
Calorific value, density, compressibility and
Wobbe index are calculated from a gas composition in accordance with
ISO6976 1983 and 1995. Gas compressibility is also calculated at
standard and line conditions in accordance with AGA8 1994.
Superior(Gross) and Inferior(Net) calorific value is calculated for
ideal and real volume, mass and mole basis. Ideal and real standard
density, relative density and Wobbe index are calculated.
Gas composition to C10 with Nitrogen and Carbon
Dioxide composition is entered in %Mole. The composition may be made
up of a primary composition only or a primary composition with a C6+
or C7+ tail composition. Where a tail composition is used the primary
composition will normally be taken from an online gas chromatograph
and the tail would be obtained from periodic analysis of samples.
The primary and tail composition is normalised
to %Mole and %Mass. The entered primary and tail composition %Mole
total percentage is displayed.
The AGA8 gas compressibility calculates density
and compressibility at Metric Standard Conditions (15 deg C and
1.01325 bar a) and at line conditions entered by the user.
AGA10: 2003 calculates Speed of Sound, in
natural gas, entropy, enthalpy, and flow coefficient for gas
composition at base and line, pressure and temperature conditions.
Gas
Flow Uncertainty Calculations
The gas uncertainty calculation calculates
uncertainty in a system where differential pressure transmitters are
used to measure the pressure drop across an orifice plate or a Venturi
flow meter.
Mass and volume flow rate uncertainties can be
estimated and plotted for two differential pressure ranges.
The uncertainty calculation can combine
uncertainty where "Footprint" procedures are used, i.e. the
transmitters are sent to a laboratory, adjusted and calibrated at line
pressure then calibrated at atmospheric pressure so that they can be
checked in the field.
The formula used for the calculation is based on
ISO5167-1 and DTI Guidelines “Guidance Notes For Standards For
Petroleum Measurement” issue 5 1997. Refer to section 5
"Standards Reference" for a detailed explanation of the calculation
methods and conformity to standards.
Calculates density in accordance with
the Solartron 7915 flow computer manual using the densitometer
calibration certificate constants. Calculates density for Solartron
7811 and 7812 gas densitometers. Velocity of sound correction is not
made in this release.
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