Coriolis Mass Flow Meter for Liquid Nitrogen and LNG

Case share ：Coriolis Mass Flow Meter for Liquid Nitrogen and LNG: DN40 Cryogenic Flow Measurement

Liquid Nitrogen and LNG application

Quick Answer

A DN40 (1.5-inch) Coriolis mass flow meter with 316L stainless steel tubes, rated to -200 degC and 20.6 bar (300 PSIG), measures liquid nitrogen (LN2) and LNG accurately at flow rates between 0.227 and 22.7 m3/h (1-100 GPM). Direct mass flow output eliminates density correction errors caused by cryogenic fluid expansion. Silver Automation Instruments supplies the SH-CMF-40 series with ATEX explosion-proof certification, 0.2% accuracy, and remote display for hazardous-area cryogenic installations.

Why Coriolis for Cryogenic Liquid Flow Measurement

Most flow technologies fail below -100 degC. Ultrasonic meters lose signal integrity as fluid properties shift at cryogenic temperatures. Turbine meters seize up because bearing clearances change drastically when the housing contracts. Variable area meters are impractical for closed cryogenic lines under pressure.

Coriolis meters measure mass flow directly through the inertial effect on vibrating tubes. There are no moving parts exposed to the process fluid. The measurement does not depend on fluid density, viscosity, or phase stability. For liquid nitrogen at -196 degC or LNG at -162 degC, that matters because both fluids sit close to their boiling points. Any heat ingress causes partial vaporization, and a density-dependent meter will read incorrectly. Coriolis reads correctly regardless.

In practice, we see this application regularly: a customer needs to custody-transfer or batch-fill LN2 into dewars, or meter LNG into small-scale distribution trucks. Custody transfer requires 0.2% accuracy. Coriolis at DN40 delivers that.

DN40 vs DN25: Why 1.5 Inches for This Flow Range

Coriolis flow meter for liquid nitrogen and LNG

Both the LN2 application and the LNG application in this case share the same pipe size options (1 inch or 1.5 inches) and the same flow range: 1-100 GPM (0.227-22.7 m3/h). That overlap makes a single meter size the logical choice.

At 100 GPM through a 1-inch (DN25) Coriolis meter, velocity exceeds acceptable limits and pressure drop becomes significant. Liquid nitrogen has very low viscosity (around 0.16 cP at -196 degC), which means it moves fast and turbulently in small-bore tubes. A DN40 (1.5-inch) meter keeps velocity in the normal operating range across the full 1-100 GPM span, with acceptable pressure drop and no risk of cavitation-driven measurement error near the lower end.

So one DN40 meter covers both projects. No need for two different bore sizes.

SH-CMF-40 Coriolis Meter: Full Specification

Parameter	Specification
Model	SH-CMF-40-P7-H2-T4-O1-C2-E1-A2-B1-P1-M1-PC1
Nominal Bore	DN40 (1.5 inches)
Flow Range	0-22 T/h (0-22.7 m3/h / 1-100 GPM for water-density reference)
Operating Pressure	2.5 MPa (25 bar / 362 PSIG) maximum
Operating Temperature	-200 to +150 degC
Accuracy	0.2% of reading (mass flow)
Tube Material	316L Stainless Steel
Process Connection	Flanged
Display	Remote display with 1.2 m cable
Analog Output	4-20 mA
Digital Output	RS485 / Modbus RTU
Explosion Protection	ATEX (IEx), suitable for Zone 1/Zone 2
Transmitter Ambient Temp.	-20 to +50 degC
Power Supply	24V DC

Key Application Details

coriolis flow meter for Liquid nitrogen LN2 application

Liquid nitrogen (LN2) application: pipeline 1 or 1.5 inches, -196 degC, 300 PSIG (20.6 bar), flow 1-100 GPM. Typical uses include cryogenic dewar filling, food processing IQF tunnel supply lines, and laboratory gas supply systems.

LNG application: pipeline 1 or 1.5 inches, -162 degC (boiling point of methane at atmospheric pressure), 300 PSIG, flow 1-100 GPM. Typical uses include small-scale LNG truck loading, satellite terminal metering, and bunkering skids for marine vessels.

Both fluids are clean, single-phase liquids under operating conditions. As long as the piping is properly pre-cooled before flow starts, two-phase flow at the meter inlet is avoidable. This is a commissioning issue, not a meter limitation.

ATEX certification is mandatory for LNG installations and strongly recommended for LN2 service near oxygen-enrichment risk zones. The SH-CMF-40 with E1 option carries ATEX approval for Zone 1.

FAQ

Can one Coriolis meter handle both LN2 and LNG in alternating service?

Not recommended for shared duty. LN2 (-196 degC) and LNG (-162 degC) are different fluids with different material compatibility considerations for seals and flange gaskets. More practically, a meter used in both services would require complete warm-up, purge, and recool cycles between each fluid change, which is operationally impractical. Dedicate one meter per fluid.

Does the 0.2% accuracy apply at the low end of the range (1 GPM)?

Coriolis accuracy is stated as percentage of reading, not percentage of full scale. At 1 GPM the meter is operating at roughly 4% of its 22.7 m3/h capacity. Most Coriolis meters specify a minimum flow threshold below which accuracy degrades. For the SH-CMF-40, confirm the low-flow cutoff with the datasheet. If 1 GPM is a sustained operating point rather than just a minimum, consider a DN25 meter for that portion of the range.

What pipe insulation is required around the meter body?

The meter body itself does not require insulation for measurement accuracy, but the process piping upstream and downstream should be vacuum-jacketed or foam-insulated to prevent heat ingress and flash vaporization at the meter inlet. The transmitter head must be kept above -20 degC, so thermal isolation between the flow tube assembly and the transmitter is required, usually via the remote display cable arrangement specified in H2 configuration.

Is 316L sufficient for LNG service, or is a higher-alloy tube needed?

316L stainless steel is acceptable for both LN2 and LNG at these temperatures and pressures. It retains adequate toughness down to -196 degC and has no compatibility issues with either fluid. Higher alloys like Hastelloy C-22 are specified for corrosive cryogens or halogenated fluids, which do not apply here.

What is the lead time for this meter?

Standard lead time for the SH-CMF-40 with ATEX certification and remote display is 4-6 weeks ex-factory. For project orders of multiple units, contact us early to confirm production scheduling.