Natural gas composition

100% Methane Default (Indian Natural Gas) Customize

Methane (CH4)

Ethane (C2H6)

Propane (C3H8)

n-Butane (C4H10)

Iso-butane (C4H10)

Pentane (C5H12)

Carbon dioxide (CO2)

Nitrogen (N2)

Noble gases (Ar, modelled)

Total percentage 100.00 %

Operating conditions

Relative humidity of air (%)

Temperature (°C)

Gauge pressure (bar)

Net calorific value

Free

GCV per kg — kCal/kg

Energy loss in process — kCal/kg Energy loss = latent heat of water vapor (combustion water + atmospheric humidity in combustion air). Air taken at sea-level conditions with 21% oxygen by mole; atmospheric humidity evaluated at 25 °C ambient with the RH entered above.

 NCV for the composition — kCal/kg 

Natural gas is typically billed per SM³ (15 °C, 1 atm). Per-volume equivalents below use the same composition basis as the per-kg values above.

GCV per SM³ — kCal/SM³

Energy loss per SM³ — kCal/SM³

 NCV per SM³ — kCal/SM³ 

Density

Locked Unlocked

Z factor 0.00000 dimensionless

Molecular weight 0.0000 g/mol

 Density 0.0000 kg/m³ 

Z factor calculated using the Peng-Robinson equation of state with mole-fraction mixing rules. CO₂ and N₂ are modelled separately using their own NIST constants; noble gases are modelled as argon. All three contribute to MW and Z but not to combustion energy.

Pipe sizing

Locked Unlocked

Natural gas flow (kg/hr)

Velocity (m/s)

Ideal is 10 to 15 m/s.

in AM³ 0.00 m³/hr

in SM³ 0.00 m³/hr at 15 °C and 1 ATM

in NM³ 0.00 m³/hr at 0 °C and 1 ATM

NCV for the total NG flow 0

 Required pipe diameter 0.00 mm 

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Branded PDF with composition, conditions, NCV, density and pipe sizing — formatted for engineering review and sharing.

Methodology: Z Factor by Peng-Robinson EOS with k_ij = 0 mixing. GCV per BIS IS 4575 / NIST. NCV via ASTM/ISO latent heat reference (583 kCal/kg at 25 °C, water vapor from combustion + atmospheric humidity). Atmospheric humidity is evaluated at 25 °C ambient with the user-specified RH — combustion air is drawn from ambient, not from the gas operating temperature. CO₂ and N₂ are modelled separately using their own NIST critical constants — they contribute to mixture MW and Z factor but not to combustion energy. Noble gases are modelled as argon (helium's negative ω makes Peng-Robinson unstable above 200 K, so argon is substituted). Density via ideal gas + Z compressibility. Per-SM³ values divide mixture MW by molar volume at 15 °C, 1 atm. Pipe sizing for vapor-phase flow at operating P, T. Standard volumes (SM³, NM³) are ideal-gas conversions for display.

Disclaimer: Indicative engineering output only. Actual values depend on composition certification, calibration of instruments, fluid properties at non-standard conditions, and installation factors not modelled here. Not a substitute for engineering review. Contact GASSOL for system design.

Branch line sizing

Sizing branches for a natural gas distribution system?

Pipeline-quality natural gas distributing across multiple branches with varying flows and pressures is project engineering territory. Our team handles full network sizing — including pressure drop reconciliation, regulator selection, and burner-side validation — as part of design consultation. The single pipe-sizing tool above covers individual line sizing; for full system design, talk to engineering.

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