Cryogenic Coriolis Flow Meter

A cryogenic Coriolis flow meter is a vibrating-tube mass flow instrument built for service from −269 to +100 °C. The two-tube sensor is brought to cryogenic temperature with the line and reads mass flow directly from the Coriolis twist amplitude, density from the resonant frequency shift, and temperature from an embedded RTD. The meter sits on the cryogenic line itself; LNG terminal regasification feed, ASU LOX / LN₂ / LAr custody loop, liquid-hydrogen electrolyzer outlet to the storage Dewar, industrial-gas tank-truck loading manifold. The cryogenic-extreme build pairs a 316L or titanium wetted-part assembly with an optional vacuum-jacket sensor housing for thermal stability at the lowest temperatures.

At cryogenic temperatures every other flow-meter family runs out of platform binding. Vortex shedding stability breaks down because the medium kinematic viscosity collapses and shedding Strouhal scaling falls off. Electromagnetic meters need ≥5 µS/cm conductivity; cryogenic LN₂ and LH₂ are non-conductive. Turbine bearings cold-weld and the K-factor drifts under thermal contraction. Thermal-mass dispersion needs a stable gas calorific reference; cryogenic flashing destroys it. Ultrasonic transit-time loses coupling on the cold pipe wall. Coriolis is principle-independent of medium velocity, conductivity, and density; the vibrating tube tracks mass flow directly and the same resonance reads density. That is why Coriolis is the universal pick below −50 °C and the only family at proflowmeters.com/ rated for the cryogenic floor.

The standard cryogenic-extreme build (−269 to +100 °C, no jacket) handles most cryogenic delivery service; LN₂ tank-truck loading, LAr cylinder fill, ASU custody on insulated piping. The vacuum-jacket sensor option adds a stainless outer shell with the inter-shell space evacuated, suppressing heat ingress and stabilizing the sensor zero point on the lowest-temperature media. Pick the vacuum-jacket build for liquid-hydrogen service (−253 °C, where 1 °C zero drift = visible accuracy degradation), LOX custody where ambient frost forms on a bare body, and any installation where the surrounding piping uses vacuum-jacketed transfer lines for the same reason. The vacuum-jacket build is configurator-selectable; quote includes the jacket evacuation certificate from the factory.

For LNG (−162 °C) the routing splits by service. A cryogenic-rated turbine works on small-bore cryo transfer where the LNG is sub-cooled and single-phase, the buyer accepts ~±0.5 % rate, and bearing thermal-contraction recalibration is acceptable. A cryogenic Coriolis covers the same service plus everything the turbine cannot: two-phase tolerance at flashing onset, direct mass output (no density correction loop needed for billing), wider turndown, and a density measurement that doubles as a process indicator for LNG composition drift. For LNG terminal fiscal billing at the regasification skid, the Coriolis is the standard pick; the mass output is the audit basis under the LNG sale-purchase agreement; volume-from-turbine plus separate densitometer + temperature is the legacy alternative.

Yes; the cryogenic-extreme build with vacuum-jacket sensor option covers −269 to +100 °C, which encloses the LH₂ service temperature of −253 °C with margin. Wetted-part material is 316L standard (austenitic, hydrogen-compatible) or titanium upgrade where chloride or hydrogen-embrittlement-conservative practice is preferred. The transmitter is mounted remotely on a stand-off with up to 50 m cable run; this keeps the electronics in the −40 to +60 °C operating window while the sensor stays on the LH₂ line. Pre-cool the sensor with the line before service per the install rules; thermal shock on commissioning is the dominant cause of zero-point drift on LH₂ meters. Calibration traceability ships with each meter for the buyer’s type-approval submission to a notified body on fiscal-billing applications.

Standard lead time is 5 to 7 business days from order confirmation, factory direct. Each meter ships with an ISO 9001 calibration certificate listing the K-factor (mass calibration coefficient), the density coefficient pair (D1 and D2), the calibrated DN, and the tested flow range. Cryogenic-build meters add the cold-zero verification record taken at calibration; vacuum-jacket builds add the jacket evacuation certificate with the measured ultimate vacuum reading and helium-leak test result. Hazardous-area certification is Ex d [ia] IIC T6 Gb (flameproof body with intrinsically safe sensor connection). EMC compliance is to EU Directive 2014/30/EU. Type approval for fiscal LNG / LH₂ / LOX custody under OIML or comparable metrology regime is buyer-arranged with a notified body; the factory provides build documentation and traceable calibration records to support that submission.