Fouling Factor Calculator

R_f = 1/U_fouled − 1/U_clean — thermal resistance added by fouling deposits. Calculates fouling factor from measured U values, or predicts fouled U from a known R_f and clean U.

Heat Transfer · HX Design · Fouling

Inputs

Solve for:

Clean overall heat transfer coefficient Uclean (W/(m²·K))

U_clean — measured before fouling develops

Fouled overall heat transfer coefficient Ufouled (W/(m²·K))

U_fouled — measured after deposit formation

Compare measured R_f against TEMA standard (optional):

Theory

Fouling resistance definition:

R_f = 1/U_fouled − 1/U_clean [m²·K/W]

U_fouled = 1 / (1/U_clean + R_f) [W/(m²·K)]

h_f = 1/R_f [W/(m²·K)] fouling coefficient

Where fouling fits in the overall U formula:

1/U = 1/h_i + R_f,i + t/k + R_f,o + 1/h_o

R_f,i, R_f,o = inner and outer fouling resistances (independent)

TEMA standard fouling factors (m²·K/W):

Service	R_f [m²·K/W]
Steam / treated cooling water	0.0001
Seawater (below 52 °C)	0.0001
City / treated water	0.0002
River water	0.0003
Hard water	0.0006
Crude oil (mild)	0.0003 – 0.0005
Fuel oil / residuals	0.0009

TEMA factors are conservative design margins for clean fluid at normal operating temperatures. Actual fouling at a given service time may differ significantly.