(e.g. turbine, vortex, ultrasonic) are not affected by compositional
changes to the extent that pressure-based and thermal flowmeters are, but few exhibit the degree of
turndown necessary to accurately measure the full range of flare gas flow. Multi-path transit-time
ultrasonic flowmeters show promise in this challenging application, but their relatively high cost
(especially at the large pipe diameters typical of flare headers) is a limiting factor.