CALDON LEFM 280CiRN Ultrasonic flowmeter


Measuring oils with high viscosity and/or low flow conditions may involve operating at Reynolds numbers below 10,000, in the laminar and transition flow regimes. Full-bore ultrasonic flow meter performance traditionally has degraded for Reynolds numbers below 10,000 because the liquid velocity profile erratically switches between laminar and turbulent characteristics. The CALDON LEFM 280CiRN ultrasonic flowmeter has a reduced bore design modeled after flow nozzle technology in which the liquid velocity profile is stabilized in the throat by forces much larger than the forces imposed by fluid viscosity. The meter stabilizes the flow profile while preventing boundary layer separation under all operating conditions, greatly improving performance.

The eight-path design of the CALDON LEFM 280CiRN flowmeter resists installation errors better than any other ultrasonic meter. The cross-plane acoustic paths make the meter immune to the effects of swirl and eliminate the need for an upstream flow conditioner. The effects of swirl on the two paths in each individual chordal plane are equal and opposite to each other, any effects from swirl are cancelled out. When the velocity readings from all eight paths at 4 chordal planes are averaged together, any effects from swirl are cancelled out. The design also minimizes the requirement for upstream and downstream straight pipe runs.

The elimination of a flow conditioner and the need for shorter lengths of upstream pipe reduce the installed cost for the CALDON LEFM 280CiRN flowmeter. This elimination also means lower overall pressure loss, which equates to annual savings in pumping costs.

The CALDON LEFM 280CiRN flowmeter has improved repeatability compared to standard full-bore meters and also can be considered for applications when the meter is to be verified in-situ using a prover to reduce the number of runs required.


Standard Features
  • Reduced-bore design for high performance under laminar, transition, or turbulent flow
  • Excellent repeatability that reduces the number of runs required to verify the meter in-situ with a prover
  • Electronics that can be integrally or remote pipe mounted
  • Available in 6" to 36" sizes
  • ±0.10% linearity over 15:1 nominal flow range for all sizes
  • No limit on operating Reynolds number
  • OIML R 117-1 Edition 2019 (E); Accuracy Class 0.3

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