ASTM D341

Operating Viscosity

Predict viscosity at any operating temperature knowing just two reference points. Based on the Walther equation (ASTM D341).

Viscosity at operating temperature

Enter two known points and the operating temperature

Reference point 1

T₁ — Temperature (°C)

Reference temperature 1

ν₁ — Viscosity at T₁ (cSt)

Kinematic viscosity at T₁

Reference point 2

T₂ — Temperature (°C)

Reference temperature 2

ν₂ — Viscosity at T₂ (cSt)

Kinematic viscosity at T₂

Operating temperature

T_op — Operating temperature (°C)

Temperature at which you want to know the viscosity

Values are theoretical (ASTM D341). Validate with direct measurement for critical applications.

Walther model: W(T) = log₁₀(log₁₀(ν + 0.7)), linear on a log-log scale of absolute temperature. Valid for ν > 2 cSt in industrial lubricants.

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