High-Pressure Common Rail

Canonical Definition

A diesel fuel injection system in which fuel is pressurised to 1,400–2,500 bar in a common accumulator rail and distributed to individual solenoid or piezo-actuated injectors that fire multiple times per combustion cycle. HPCR injectors have plunger-barrel clearances of 1–3 µm and injection orifice diameters of 80–200 µm, making them the most contamination-sensitive components in modern diesel engines. ISO 12 cleanliness class or better (typically ISO cleanliness code for fuel: <18/16/13) is required. Even soft contaminants such as biological growth, wax, and oil carry-over can cause injector stiction and deposit formation.

Engineering Context

HPCR systems require the highest fuel cleanliness standards ever specified for production engines. A single particle of silica above 5 µm can permanently scar an injector plunger, causing fuel leakage past the plunger and loss of injection pressure. HPCR-compatible filtration must achieve absolute ratings at 2–6 µm to protect injection components at the quantities of particles present in typical bulk diesel.

Applicable Standards

Related Technologies

Protection Systems

Knowledge Center Articles

Related Terms