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Liquid Properties at Conditions Calculator

ASTM D341 | Density, Viscosity, Bulk Modulus & More at Operating Conditions

Liquid Properties at Conditions
Calculate physical properties of petroleum liquids and water at any temperature and pressure. Uses API gravity correlations for density, ASTM D341 Walther equation for viscosity interpolation, and industry-standard methods for bulk modulus, vapor pressure, surface tension, and thermal expansion.

Liquid Selection

°API

Operating Conditions

psia

Viscosity Reference Points (ASTM D341)

Two temperature/viscosity pairs enable ASTM D341 Walther equation interpolation.
°F
cSt
°F
cSt

📚 Learn the Theory

Understand liquid property correlations, ASTM D341 viscosity, and API gravity methods

Read Engineering Guide →

Formula Reference

API Gravity → SG:
SG = 141.5 / (API + 131.5)
ASTM D341 (Walther):
log(log(ν + 0.7)) = A − B·log(T)
Bulk Modulus:
K = ΔP / (ΔV/V)
SG = Specific gravity (water = 1.0)
ν = Kinematic viscosity (cSt)
T = Absolute temperature (°R)
A, B = Walther constants from reference data
K = Bulk modulus (psi)

Standards & References

  • ASTM D341
    Viscosity-Temperature Charts for Liquid Petroleum Products
  • API MPMS Ch. 11.1
    Temperature and Pressure Volume Correction Factors
  • GPSA Engineering Data Book
    Physical Properties of Hydrocarbons
  • API Technical Data Book
    Petroleum Refining, Physical Properties

Important Notes

  • ASTM D341: Requires two known viscosity/temperature points for interpolation
  • API Gravity Range: Correlations valid for 5–80° API
  • Temperature Limits: Extrapolation beyond reference data may be inaccurate
  • Pressure Effects: Significant above ~1,000 psia for most liquids
  • Vapor Pressure: Uses Reid vapor pressure correlations
  • Presets: Default viscosity pairs loaded for common liquids
  • Professional Review: Verify with licensed PE for final design

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