The Micro-Separometer (MSEP) test is used for aviation turbine fuel to assess the fuel-water separation characteristics under the specified test procedure. It is related to the presence of surface-active materials that can interfere with separation.
Role of surface-active compounds
Surfactant-like contaminants can stabilize fine water droplets or emulsions, making water separation more difficult. This is why fuel cleanliness and handling practices are important in aviation fuel quality control.
The reported MSEP result should always be interpreted against the applicable specification and method requirements for the fuel being tested.