Fuel Viscosity Temperature Calculator
Calculate the required fuel pre-heating temperature to achieve the target viscosity at the main engine inlet using Walther-ASTM principles.
Fuel Properties Input
Calculation Method for 'B' Constant
Engine Requirement
**Disclaimer:** This calculator uses the Walther-ASTM equation principles: log(log(ν+k)) = A - B log(T_abs). The constant 'k' (typically 0.6-0.8 for fuel oils) and 'B' (slope) are critical. Accuracy depends heavily on correct input values and fuel characteristics. Always cross-verify with official purifier/heater manuals and viscosity control system readings. This tool is for estimation and educational purposes.
Ensure viscosity values (ν) are such that (ν+k) > 1 for valid log-log calculations.
About Fuel Viscosity Temperature Calculator
Fuel Pre-Heating for Optimal Atomization
Inside a ship's engine room, Heavy Fuel Oil (HFO) must be heated to a specific temperature range to ensure correct atomization at the fuel injectors. If the fuel is too cold (high viscosity), it won't burn completely; if it's too hot (low viscosity), it might cause gas lock or cavitation in the high-pressure pumps.
Calculation Formulas
Walther-ASTM Equation (D341):
log₁₀[log₁₀(ν + k)] = A - B × log₁₀(T)
Where:
ν: Kinematic Viscosity (cSt) | T: Temperature (Kelvin) | k: Constant (Standard 0.7) | B: Fuel Slope Constant
Operational Directions
- Gather Data: Find the viscosity (v1) and temperature (T1) from your most recent bunker test report (found on the BDN).
- Target Viscosity: Check the engine builder's manual for the required viscosity at the inlet (typically between 10 and 20 cSt).
- Two-Point Calculation: For maximum precision, provided two different viscosity/temperature points from the lab report to calculate the fuel's specific 'B' slope constant.
- Adjustment: Use the calculated temperature as a set point for your fuel oil heaters.
Important Warning
Actual viscosity can be influenced by fuel blending or contaminants. Always monitor the Viscotherm (on-line viscometer) on your vessel to ensure the heaters are maintaining the target viscosity at all times during engine operation.