The information in this document is limited to aircraft engine fuel feed, refueling, and transfer components (reference 2.1). It is assumed that isothermal, liquid fluid conditions exist, herein referred to as fuel. Where a unit of measure is suffixed, this is intended to show a generally associated unit for illustration only and is not an exclusive endorsement of this particular term. Where applicable and allowable it is understood that a referee fluid may be substituted for fuel.