Q = volumetric flow rate (m³/s on a specified basis)
P = absolute pressure (Pa)
T = absolute temperature (K)
Z = compressibility factor (dimensionless)
ṅ = molar flow rate (mol/s)
Subscripts: s = Standard base (S), n =
Normal base (N), act = Operating/Actual (A)
Formulas / Logic
Gas law with real-gas correction:
ṅ = (P · Q) / (Z · R · T)
Convert input volumetric flow to molar flow using its basis (S / N /
A).
Convert molar flow back to volumetric flow at target basis:
Q_target = (ṅ · Z_target · R · T_target) / P_target
Time-base conversions: 1 h = 3600 s, 1 day = 86400 s.
US customary volume: 1 ft³ = 0.0283168466 m³ (used for SCF/ACF
conversions).
Assumptions / Notes
Standard base (S) is fixed at 15°C and 101.325 kPa; Normal base (N) is
fixed at 0°C and 101.325 kPa. Unit dropdowns in the reference sections
change display only.
Pressures must be absolute (not gauge). Temperatures
must be above absolute zero; Z must be > 0.
Accuracy depends on the selected Z_act. For
custody-transfer / metering applications, obtain Z using recognized
standards/correlations (e.g., ISO 12213 / AGA Report No. 8) suitable
for your gas composition, pressure and temperature.
Reference condition guidance: ISO 13443 specifies standard reference
conditions for natural gas measurements; ISO 15970 gives
requirements/procedures for measurement inputs used for volume
calculation and volume conversion.
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