How we measure

FLUXUS - Measurement according to the Transit-Time Difference Principle

The FLUXUS range of non-invasive ultrasonic gas and liquid flow meters measure according to the Transit-Time Difference Principle.

This measurement method exploits the fact that the transmission speed of an ultrasonic signal depends on the flow velocity of the carrier medium. Similar to a swimmer swimming against the current, an ultrasonic signal moves slower against the flow direction of the medium than when in flow direction.

For the measurement, two ultrasonic pulses are sent through the medium, one in the flow direction, and a second one against it. The transducers are alternatively working as an emitter and a receiver. The transit-time of the ultrasonic signal propagating in the flow direction is shorter than the transit-time of the signal propagating against the flow direction.

A transit-time difference, Δt, can thus be measured and allows the determination of the average flow velocity based on the propagation path of the ultrasonic signals. An additional profile correction is performed by our proprietary algorithms, to obtain an exceptional accuracy on the average flow velocity on the cross-section of the pipe - which is proportional to the volume flow, and when temperature and pressure compensated, to the mass flow. In case solids or gaseous entrainments are exceeding a threshold 10% of the total volume flow, FLUXUS automatically switches to its built-in HybridTrek mode, ensuring acurate and reliable measurment data even at such challenging applications.

Since ultrasounds propagate in solids, the transducers can be mounted onto the pipe. The measurement is therefore non-invasive, and thus no cutting or welding of pipes is required for the installation of the transducers.

PIOX - Process Analytics via Ultrasound or Refractometry

FLEXIM's range of PIOX process analyzers work, in case of PIOX S, also non-invasively by ultrasound. Additionally to the measurement of the transit time difference, PIOX S also determines the mediums sonic velocity, which correlates to a mediums concentration and density.

In contrast, the Process Refractometer PIOX R works according to a completely different measurement technology: The patented transmitted light measurement principle.

Here, the refractometer measures the refraction of a light beam that is transmitted through the medium. The angle of refraction strictly correlates to the mediums concentration. In comparison to conventional  process refractometers that works according to the critical angle principle, PIOX R is completely unaffected by measurement drift caused by deposits on the prism.