Static Electricity and Fuel Fire Risk
When hydrocarbon fuels flow through pipelines, pass through filters, or are loaded into storage tanks and aircraft, friction between the fuel and contacting surfaces generates electrostatic charge. Highly refined fuels, particularly ULSD, Jet-A/A-1, and hydrocracked products, have extremely low electrical conductivity, meaning generated charge cannot dissipate quickly. Charge accumulates at the fuel surface, creating high-voltage potential that can discharge as a spark directly into the fuel vapor space above the liquid.
With ignitable fuel-vapor-air mixtures present during tank filling and loading operations, an electrostatic discharge represents a real and well-documented ignition hazard. Static Dissipator Additives address this by increasing fuel conductivity by several orders of magnitude, allowing charge to relax to earth rapidly rather than accumulate to discharge potential.
Critical distinction: SDAs are not a substitute for proper earthing and bonding during transfer. They are complementary. SDAs reduce the rate of charge generation and accelerate dissipation; earthing and bonding provide the return path to ground. Both are required for safe fuel transfer operations per EI and IATA standards.
How SDAs Work
These compounds ionize in the fuel, providing mobile charge carriers that enable static charge to flow to earth rather than accumulate. SDAs (e.g. Stadis 450) work at very low treat rates, typically 1–3 mg/kg, achieving the target conductivity range of 50–600 pS/m specified for aviation fuel. Conductivity must not exceed the maximum limit, as over-treatment can interfere with certain aircraft fuel gauging systems.
Application Areas
| Application | Static Risk | SDA Requirement |
|---|---|---|
| Aviation Turbine Fuel (Jet-A/A-1) | High risk at aircraft wing refueling, pressure refueling operations, and high-flow filter separators | Required per DEF STAN 91-091 and EI 1529; conductivity 50–600 pS/m; approved products only (e.g. Stadis 450) |
| ULSD / Low-S Diesel | Moderate risk at high-flow terminal loading, pipeline injection, and rail loading | Used by terminals and refiners at high throughput; prevents filter-separator charge buildup |
| Marine Bunker Loading | Risk during high-flow bunkering operations, particularly for low-viscosity VLSFO and MGO | SDA applied at loading point; reduces risk during high-volume transfer to ship tanks |
| Refinery Pipeline / Loading Arms | Charge generation through product filters and flow meters at high flow rates | SDA in refinery product stream reduces static discharge risk at loading arms and open tank tops |