of obstruction and increase the flow area the petal valve stiffness is selected to so as to accommodate the anticipated range of flow rates the resulting reduced change in differential pressure over a given flow range allows the flow meter to be useful over a wider flow range the variable venturi throat design is self regulating so its flow rate versus flow area relationship will be repeatable and therefore flow rate versus pressure drop is predictable as a result a rangeability of 30 to 1 is achievable and can readily accommodate for example a flow range of 200 to 6000 pph the obstruction valve additionally includes a support structure 48 that is disposed on its downstream side which serves to prevent the petal valves from creasing or taking a set and functions as a stop by preventing the petal valves from being damaged both the repeatability of flow measurement is enhanced and service life is extended the densitometer 36 consists of a capacitance probe in the form of a set of concentric tubes 50 52 54 56 through which the fuel flows the dielectric constant of the fuel is measured as it passes through the tubes since the fuel density can be correlated to the dielectric constant it can be used as a density sensor when the signal is corrected by fuel temperature the fuel temperature measurement is achieved by bonding a film temperature sensor 58 to the densitometer surface this temperature signal is used to correct the density reading and the mass.