We use ASTM D7061 to measure the Separability Number, sometimes termed Reserve Stability Number (RSN), of residual and low-sulphur blended fuels.

Separability Number (SN), indicates the resistance of a fuel to form sludge.

Hot filtration methods (HFT) such as TSP, will indicate the amount of sediment present in a fuel, whereas SN will indicate the likelihood that this sediment will flocculate and form sludge.

SN is an excellent accompaniment to the routine hot filtration methods. It can identify potentially troublesome fuels (unstable) even when the HFT method is indicating a low sediment content.

Conversely, it may indicate that a high sediment fuel is in fact quite stable and unlikely to form sludge.

This information in combination, is extremely useful from an operational perspective, as it will indicate in advance if and what mitigation steps are appropriate.