Abstract: A tube through which fluid flows is installed in a fluid system. A piezoelectric driver is mounted on the exterior of the tube. A piezoelectric sensor is also mounted on the exterior of the tube. A feedback loop from the sensor to the driver is adapted to cause vibrations in the tube at its resonant frequency or a harmonic thereof. One or more strain gauges mounted on the exterior wall of the tube sense the strain exerted on the exterior wall by the pressure of the fluid flowing through the tube. A temperature sensor mounted on the exterior wall of the tube senses temperature. A microprocessor determines the density of the fluid flowing through the tube responsive to the piezoelectric sensor, temperature sensor and the one or more strain gauges. The one or more strain gauges comprise a bridge circuit. Strain gauges comprise two arms of the bridge circuit and temperature dependent resistors comprise the other two arms of the bridge.

Abstract: A densimeter is provided that is mounted on the side of a conduit carrying a fluid flow. The densimeter consists of an inlet and an outlet scoop which are immersed into the fluid flow through the conduit. A portion of the fluid flow enters into the first scoop and is directed into the densimeter where the fluid's density is measured and then exits through the exit scoop back into the fluid flow in the conduit.

Abstract: The parameters of flowing fluids are measured via the insertion of a two rotor assembly into the flowing fluid, the rotors adapted to rotate at different free running speeds, and being coupled such that the rotors share a common axis, and such that an angular displacement of one rotor relative to the other rotor applies a restoring torque to the other rotor, the restoring torque being dependent on the amount of angular displacement. The fluid flow induced angular displacement is related to the fluid mass flow rate, and the time interval between the passage of the rotors through a fixed reference plane extending radially from the common axis of the rotors is related to the density of the fluid. The apparatus incorporates rotors that are coupled by connecting them with a plurality of spring elements at two or more positions radially outward from the common axis of the rotors. The rotors may be oriented such that the rotor which is upstream in the flow is adapted to have a slower free running speed.

Abstract: A double cycle prover is used to calibrate meters which require long proving runs. A small volume or piston prover and a master flowmeter, are coupled in series with the meter under test, then the master flowmeter is calibrated against the small volume prover, and the meter under test is calibrated against the master flowmeter. A signal processor combines the proving cycles, to relate the small volume prover to the meter under test. A density meter is connected to the flow channel, if the meter under test is a mass flowmeter, and the signal processor uses the density measurement to relate the mass flow measurement of the meter under test with the volume flow measurement of the master flowmeter.

Abstract: A fluid flowmeter prover uses a measuring cylinder in series with a flowmeter to calibrate the flow meter. The cylinder has a piston which travels in synchronism with the fluid, the flow rate of which is to be measured. At the downstream end of the cylinder, a poppet valve connected to and within the piston opens to allow the fluid to pass through the piston. The poppet valve has a valve rod connected to a first coupling. A second coupling engages the first coupling and through a motor draws the valve and piston to the upstream end of the cylinder where they disengage, releasing the valve and allowing it to close for another run. The cycle repeats when the second coupling is driven down to reengage the first coupling.

Abstract: A dynamic leak detector is connected to a fluid flowmeter prover. The prover has a measurement chamber with a fluid inlet and a fluid outlet and a barrier which moves axially through the chamber between the fluid inlet andc the fluid outlet. First and second spaced apart seals between the barrier and the chamber interior prevent fluid from passing through the barrier. The leak detector is connected to the space between the first and second seals and urges fluid to flow out through the seals into the chamber, while the prover is operating. If more than a threshold amount of fluid passes through the seals during a test run, the operator is alerted and the test run is rejected.

Abstract: A mechanical displacement flowmeter calibrator has a first fluid line external of the measuring cylinder of the calibrator connected between the inlet and outlet thereof. A flowmeter that produces flow-representative pulses is connected in the fluid line. A rod is connected to a measuring piston adapted to travel through the measuring cylinder as a fluid barrier. The rod drives the measuring piston through the measuring cylinder at a predetermined, constant speed and thereby determines the flow rate of the calibration. The displacement of the measuring piston is sensed as it travels through the measuring cylinder during a test run, while the pulses produced by the flowmeter are counted during the time interval in which the piston displaces a given volume. The flowmeter is preferably connected in the fluid line at the pressure null point. First and second annular edge seals around the periphery of the measuring piston form an annular cavity into which pressurized fluid, preferably a lubricant, is injected.