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Instrumentation and Measurement 47

include nuclear and sonic-type meters (nonintrusive devices). As with
Coriolis meters, pricing has become reasonable for many applications.

2.1.3.1 Types of Fluid properties Measured Over Time and Why
Falcone et al. (2009) described five essential parameters measured (sepa-
rately) by flowmeters:
• Meters that measure fluid flow velocity (v). This category includes classical
intrusive meters that have spinners or turbines. A flow passing through
the vane of the device moves the spinner; the rate of spin per time is mea-
sured to calculate the volumetric flow. Turbine, spinner, or vortex
meters are the most common devices that measure the total flow veloc-
ity. Most fluids have multiple components (liquid, gas, etc.) The main
way to improve precision and accuracy of these devices is to homogenize
the fluids and measure total fluid velocity. Under this regime, a turbine
meter can measure the total fluid velocity of the mixture but it cannot
measure the fluid density.
• Meters that measure density (ρ). Nonintrusive devices based on ultrasonic,
electrical impedance, or particular atomic constituents can measure the
mean density of a fluid on a section of a pipe. This category includes
γ-ray adsorption or neutron interrogation. These devices measure the
void fraction of the gas and the liquid, but it cannot measure fluid
velocity.
• Meters that measure mass flow (ρ.v). These devices use a flexible tube
that measures the amount of mass passing through a u-shaped pipe,
causing vibrations; the vibration is converted into total mass flow.
This category includes Coriolis meters and true mass flowmeters
(TMFM).
2
• Meters that measure momentum (ρ.v ). The product of mass flux
(density * velocity) and fluid flow velocity is defined as fluid momen-
tum, or the force of a fluid in motion. This category includes traditional
intrusive pressure-drop devices, such as orifices, Venturi, nozzles, etc.
The pressure drop is measured directly between the inlet and outlet pres-
sure points.
• Meters that measure chemical or atomic elements (H 2 ,C 2 ,O 2 ). This category
includes electrical, mechanical, acoustical, hydraulic, or atomic devices
that, depending on their physical principles, measure the concentration
and velocity of atomic elements such as hydrogen, carbon, and oxygen.
For example, infrared spectroscopy water cut device measures the
volumetric proportion of oil in a mixture of oil and water by running
a beam of infrared light that is absorbed by oil fluid.