Coriolis
Measures mass flow from the effect of fluid moving through oscillating measuring tubes. Tube count, material, geometry and operating frequency depend on the instrument; some designs also measure density and temperature.
A driver makes one or more measuring tubes oscillate. Flow through the oscillating tube produces a measurable Coriolis effect; sensors detect the resulting motion difference to determine mass flow. Tube geometry and sensing arrangements vary by instrument. Some instruments also derive density and measure temperature, but these functions and their accuracy belong to the selected model.
In plain terms
Like a child's swing carrying a passing ball — when the ball flies through the swinging seat, the seat momentarily torques aside; bigger or faster ball, bigger torque, and that torque is your mass.
Why designers use it
- Measuring mass flow directly rather than calculating it from a separate volume-flow and density measurement.
- Obtaining additional density or temperature measurements when the selected instrument supports them.
- Metering compatible fluids within the instrument's documented accuracy, installation and operating requirements.
Best for
- Custody transfer
- Process control
- Food and pharma
Key specifications
- Operating limits: Check the exact manufacturer's datasheet (A family name does not establish voltage, current, temperature or timing limits.)
- Pin assignment: Match the complete part and package code (A similar name or function does not guarantee the same wiring.)
- Mechanical fit: Use the exact package drawing (Check pad layout, dimensions and viewing direction before building.)
When not to use it
- On large-bore pipes where the meter cost (a 6-inch Coriolis is tens of thousands of dollars) dwarfs the value of high accuracy — pull a magmeter or ultrasonic.
- With high entrained gas (slug flow) — a two-phase mixture damps the resonance and the Coriolis tube reports nonsense; use a multiphase meter.
Common mistakes
- Mounting the meter near a pump's pulsating discharge — the pulses entrain the natural frequency and the phase reading shakes.
- Skipping mid-life recalibration — the tube's natural frequency drifts as deposits build up, and 'mass flow' starts to read 0.5 % off.
Where you will find it
- An Emerson Micro Motion ELITE CMFS Coriolis on a Texas custody-transfer LACT skid measures crude oil flow at 4,000 bbl/h with ±0.05 % accuracy: the meter's ENP-coated tubes shrug off the paraffin-laden Permian crude that would foul a turbine meter monthly.
- An Endress+Hauser Promass F300 in a Lindt chocolate factory's tempering line meters mass flow of liquid cocoa butter at 60 °C: the Coriolis tube simultaneously reports density (telling the operator the cocoa-fat ratio in real time) so the recipe stays in spec without manual sampling.
- A KROHNE OPTIMASS 6400 Coriolis on a hydrogen-truck loading station at an Air Liquide refuelling depot meters cryogenic LH₂ at −253 °C: the meter's titanium tube tolerates the thermal shock and reports the mass loaded into a Hyundai Xcient fuel-cell truck within ±0.2 %, supporting H₂-by-the-kilogram custody transfer.
A short history
A Coriolis flowmeter vibrates a measuring tube. Flowing fluid changes the tube's motion, creating a measurable difference between signals from sensors along it. The instrument relates that difference to mass flow, making the method useful for tasks such as dosing and transfer measurement.