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Water Content Calculator

McKetta-Wehe Correlation

Gas Water Content Calculator (GPSA Method)
Calculates saturated water content in natural gas using McKetta-Wehe/Bukacek correlations. Determines dewpoint temperature and specification compliance for dehydration system design.

Operating Conditions

°F
Valid: -60°F to 400°F
psia
Valid: 1-15,000 psia

Gas Properties

-

Sweet natural gas: 0.55-0.70
Rich/wet gas: 0.70-0.85

Industry Specifications

Pipeline ≤ 7 lb/MMscf
Sales gas ≤ 4 lb/MMscf
Cryogenic ≤ 1 lb/MMscf

📚 Learn the Theory

Detailed coverage of gas water content, McKetta-Wehe charts, GPSA correlations, and dehydration requirements.

Read Engineering Guide →

Correlations Used

W = W14.7 × (14.7/P) × Cg
W = Water content (lb/MMscf)
W14.7 = Sat. water at 14.7 psia (McKetta-Wehe)
P = Operating pressure (psia)
Cg = Gas gravity correction

Gravity correction: Cg = (1 + SG) / 1.6

Standards & References

  • GPSA
    Section 20, Figure 20-3 (McKetta-Wehe)
  • Bukacek Correlation
    IGT Research Bulletin No. 8 (1955)
  • ISO 18453:2004
    Natural Gas - Water Content Correlation
  • GPA 2145
    Physical Constants for Paraffin HC

Engineering Notes

  • Sweet gas only: Acid gases (CO₂, H₂S) increase water solubility 5-15%
  • Correlation accuracy: ±3-5% for 60-200°F, 100-3000 psia range
  • Dehydration methods: TEG achieves 2-7 lb/MMscf; molecular sieve <0.5 lb/MMscf
  • Temperature effect: Water content roughly doubles per 20°F increase
  • Pressure effect: Water content inversely proportional to pressure

Common Errors

  • Using gauge pressure instead of absolute (psig + 14.7 = psia)
  • Applying sweet gas correlation to sour gas
  • Confusing ppmv with lb/MMscf (not 1:1 conversion)

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