In which situation would you use a filter separator?

Using a filter separator is essential when the goal is to remove water and particulates from fuel. Filter separators are specifically designed to effectively separate contaminants, such as water and solid particles, from fuel before it is used or stored. This process helps ensure that the fuel meets quality standards and prevents damage to engines or equipment that may occur if contaminants are present.

In scenarios involving the other options, such as increasing fuel pressure, transferring fuel, or fueling aircraft, filter separators do not serve those specific functions. Increasing fuel pressure typically requires a pump or pressure regulator. Transferring fuel generally involves pumping mechanisms rather than filtration. Fueling aircraft has its own stringent requirements and protocols that may not directly involve filtration processes at that moment. Thus, the primary and most accurate situation for using a filter separator focuses on enhancing fuel quality by removing unwanted substances.