A flow metering system, comprising: an ultrasonic flow metering system comprising: an ultrasonic flow meter having a meter body defining a central passage, the ultrasonic flow meter constructed to be coupled to a structure carrying fluids, and configured to measure volume of fluid flowing through the central passage; and a first pressure sensor disposed in the meter body or downstream of the ultrasonic flow meter to measure pressure of the fluid proximate the ultrasonic flow meter; a flow conditioner disposed upstream of the ultrasonic flow meter; a second pressure sensor disposed upstream of the flow conditioner to measure pressure of the fluid upstream of the flow conditioner; and a condition monitor coupled to the ultrasonic flow meter and the pressure sensors (136, 304), and configured to: identify a potential discrepancy in operation of the flow metering system based on a difference between pressure measurements of the first and second pressure sensors (136, 304); establish a reference pressure difference between the first and second pressure sensors (136, 304); and compute an expected value of pressure proximate the ultrasonic flow meter based on the reference pressure difference and the pressure measured by the second pressure sensor. an ultrasonic flow metering system comprising: an ultrasonic flow meter having a meter body defining a central passage, the ultrasonic flow meter constructed to be coupled to a structure carrying fluids, and configured to measure volume of fluid flowing through the central passage; and a first pressure sensor disposed in the meter body or downstream of the ultrasonic flow meter to measure pressure of the fluid proximate the ultrasonic flow meter; an ultrasonic flow meter having a meter body defining a central passage, the ultrasonic flow meter constructed to be coupled to a structure carrying fluids, and configured to measure volume of fluid flowing through the central passage; and a first pressure sensor disposed in the meter body or downstream of the ultrasonic flow meter to measure pressure of the fluid proximate the ultrasonic flow meter; a flow conditioner disposed upstream of the ultrasonic flow meter; a second pressure sensor disposed upstream of the flow conditioner to measure pressure of the fluid upstream of the flow conditioner; and a condition monitor coupled to the ultrasonic flow meter and the pressure sensors (136, 304), and configured to: identify a potential discrepancy in operation of the flow metering system based on a difference between pressure measurements of the first and second pressure sensors (136, 304); establish a reference pressure difference between the first and second pressure sensors (136, 304); and compute an expected value of pressure proximate the ultrasonic flow meter based on the reference pressure difference and the pressure measured by the second pressure sensor. identify a potential discrepancy in operation of the flow metering system based on a difference between pressure measurements of the first and second pressure sensors (136, 304); establish a reference pressure difference between the first and second pressure sensors (136, 304); and compute an expected value of pressure proximate the ultrasonic flow meter based on the reference pressure difference and the pressure measured by the second pressure sensor.