Surge Force in Fuel & Chemical Tankers
The complete formula and a full data table across four common liquids.
The Complete Formula
Surge force scales with liquid density, tank capacity, fill level, and road-surface friction. It does not scale with speed — braking surge force is friction-limited, not speed-dependent.
K = K_BASE × (density ÷ 7.10)
Surge = K × 47,000 × (capacity ÷ 6,000) × fill × (1 − fill) ÷ 0.20 × (CoF ÷ 0.60)
K_BASE = 3.598 · Reference payload = 47,000 lbs (80,000 lb GVW − 33,000 lb tare) · Reference density = 7.10 lbs/gal
With Surge Busters® installed, this figure drops by 96.7%, independently measured by the University of Idaho.
Full Data Table Example
The heavier the liquid, the more momentum it carries into the same stop — surge force scales directly with density. The last column shows it as a multiple of what your truck was designed to stop. UAN fertilizer exerts over 9 times more force than the braking system is designed to stop.
Worst-case fill (52.5%), standard 6,000-gallon tank, Wet Asphalt (CoF 0.60), 5 of 5 axles braked.
| Liquid | Density (lbs/gal) | Surge Force | × Braking Capacity |
|---|---|---|---|
| Fuel Oil No. 2 | 7.10 | 210,854 lbf | 7.35× |
| Water | 8.34 | 247,679 lbf | 7.96× |
| DEF | 9.07 | 269,359 lbf | 8.29× |
| UAN Fertilizer | 11.06 | 328,457 lbf | 9.07× |
Figures verified against the current Surge Force Calculator, September 2026. Run your own tank, liquid, and fill level at the Surge Calculators hub.