Clamp-on Ultrasonic Standard Volume Flow Measurement and API Determination of Hydrocarbons

FLUXUS H721 is FLEXIM’s flow and analytical measuring system for the hydrocarbon processing industry (HPI). It combines highly precise non-invasive measurement of volume flow and sound speed with sophisticated calculation features. The transmitter’s internal HPI computer calculates API gravity, operational density, density at base conditions and kinematic viscosity. Temperature and pressure compensation according to industry standards such as ASTM1250, GPA TP25 and D4311 allows for precise standard volume flow measurement of liquid hydrocarbons.

FLUXUS H721 is equipped with a database for a wide range of applications from light hydrocarbons to crude oils/refined products to heavy hydrocarbons. Application-specific parameterisation is easily possible via an editable table on the transmitter with liquid names and specific properties (density, API).

Typical applications of FLUXUS H721 are e.g. monitoring of pipeline integrity, product identification in tank farms, quality check measurements and verification or temporary replacement of stationary measuring devices.

Hydrocarbon Media Detection and Flow Measurement - FLUXUS HPI Flow Meter


Cutting-edge Features of FLEXIM's ultrasonic non-intrusive flow measurement

  • Automatic Fluid Identification and Interface Detection
  • Bi-directional flow metering
  • Superior temperature stability - No zero drift
  • Certified and traceable Multi-Point wet flow calibration
  • Robust “Fit for Purpose” Flexibility and Stability using PERMALOK mounting fixtures
  • Operational capabilities from –40 °C up to +200 °C
  • Extremely high turndown range - capability of measuring at very low flow rates

Technical Facts

Measuring quantities
  • flow: operating volumetric flow rate, standard volumetric flow rate according to ASTM 1250/TP25/4311, flow velocity, mass flow rate
  • HPI: API gravity, density, normalised density
  • interface detection: slope of the HPI physical quantities
  • fluid detection: according to fluid table
Measurement uncertainty
(volumetric flow rate)
±1 % of reading ±0.005 m/s
Transit time (HPI functions)

1/(50 • fα) ±10-4 • t

1/(5 • fα) ±10-4 • t

fα – transducer frequency
t – total transit time e.g. for transducers with transducer frequency M (fα = 1 MHz):
repeatable: 20 ns ±10-4 . t
absolute: 200 ns ±10-4 . t

Explosion protection
ATEX/IECEx zone 2
ATEX/IECEx Zone 2, FM Class I /Div 2
Power supply
100 ... 230 V AC / 50 ... 60 Hz
12 / 24 V DC
4 - 20 mA active
4- 20 mA HART active / passive
pulse / frequency / binary
Pt100 / Pt1000
4 - 20 mA active / passive
Digital communication
Modbus RTU/TCP
Profibus PA
Foundation Fieldbus
Pipe diameter range
6 mm ... 6500 mm
Temperature range (pipe wall)
-40 °C ... +240 °C
Additional Information
For more detailed Information please download the Technical Specifications

360° view


For the manual 360° view pull the image left or right


Clamp-on Ultrasonic Standard Volume Flow Measurement and API Determination of Hydrocarbons



Technical Specification
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