- By Lily Sheng
- September 30, 2025
- Feature
Summary
Coriolis mass flow meters measure mass directly and remain accurate regardless of temperature, pressure or state.
Nitrogen is one of the most widely used industrial gases, essential in electronics, food processing, energy and medical research. Depending on temperature and pressure, it can exist as a gas, liquid or solid—each with vastly different density and behavior. This variation makes accurate flow measurement challenging, particularly when handling cryogenic liquid nitrogen (LN₂) at –196°C (77 K).
Traditional volumetric or mechanical flow meters struggle in such environments. They rely on moving parts and density-based assumptions that cannot adapt to phase changes or extreme cold. In contrast, Coriolis mass flow meters measure mass directly and remain accurate regardless of temperature, pressure or state, making them ideal for nitrogen applications.
The changing nature of nitrogen
Nitrogen exists in gaseous, liquid or supercritical states depending on temperature and pressure. At 1 atm (14.7 psi), it boils at –195.8°C (–320.4°F). Even slight heat gain or pressure drop causes rapid vaporization, forming a gas–liquid mixture. Beyond its critical point (126.2 K, 3.39 MPa), nitrogen becomes supercritical, showing both gas and liquid properties.
Because nitrogen’s density changes nearly 700-fold—from about 1.17 kg/m³ in gas form (25°C, 1 atm) to roughly 808 kg/m³ as a liquid (–196°C)—minor thermal variations can distort volume-based readings. Flow meters relying on velocity or differential pressure, such as turbine, vortex, or orifice types, often become inaccurate or fail entirely under such conditions.
| State | Typical Conditions | Density (kg/m3) | Characteristics |
| Gas | 25∘C, 1 atm | ≈1.17 | Low density, compressible |
| Liquid | −196∘C, 1 atm | ≈808 | High density, cryogenic |
| Supercritical Fluid | >126.2 K, >3.39 MPa | ∼100−500 | Hybrid gas–liquid traits |
Measurement challenges in cryogenic nitrogen
Cryogenic nitrogen presents three major challenges:- Phase instability: Small pressure or temperature changes cause flashing, creating two-phase flow that volumetric meters misread.
- Material contraction and frost: Metals shrink and moisture freezes at –196°C, risking signal loss or damage.
- Rapid density shifts: Nitrogen’s properties vary sharply with temperature, requiring a method independent of density.
Why coriolis flow meters excel in nitrogen applications
The primary advantage of Coriolis meters is their ability to perform accurately at ultra-low temperatures — as low as –200°C (–328°F). Where conventional meters freeze or deform, Coriolis devices maintain precision, making them ideal for LN₂ and cryogenic gas lines.1. Built for extreme cold
Cryogenic Coriolis flow meters use 316L stainless steel or special alloys like Hastelloy or titanium, materials that stay ductile and stable under intense cold. Their vibrating tubes remain unaffected by contraction or frost. Some models include vacuum insulation or thermal isolation to prevent ice buildup and maintain signal stability.
2. Immune to density and phase changes
Coriolis meters measure mass flow through the Coriolis effect—independent of density or state. Even if nitrogen partially vaporizes, readings remain accurate, unlike volumetric meters that depend on steady fluid properties.
3. No moving parts, no freezing risk
With no bearings or rotating elements, Coriolis meters are immune to seizing or blockage. Their welded construction ensures long-term reliability with zero maintenance in cryogenic service.
4. Integrated temperature monitoring
Coriolis meters simultaneously measure process temperature, allowing operators to confirm cryogenic conditions and detect early vaporization without extra sensors.
5. High accuracy and control
With accuracy typically within ±0.2% of reading, Coriolis meters ensure precise custody transfer and process control for every kilogram of nitrogen, regardless of thermal variation. Typical Technical Scope:
- Min. temperature: –200°C (–328°F)
- Accuracy: ±0.1–0.5% of reading
- Materials: 316L SS or cryogenic alloys
- Outputs: 4–20 mA, pulse, RS485, HART, PROFIBUS DP
- Sizes: DN4 (1/8") to DN200 (8")
Conclusion
Measuring nitrogen at cryogenic temperatures requires technology that withstands extreme cold, avoids phase errors and maintains precision. Coriolis mass flow meters meet these needs through robust construction and direct mass measurement. From LN₂ filling stations to gas plants and research facilities, they have become the standard for reliable nitrogen flow monitoring — ensuring every kilogram is measured with confidence and accuracy.
About The Author
Lily Sheng is a product manager at Silver Automation Instruments. Silver Automation Instruments is a manufacturer of industrial instrumentation (flow meters, pressure transmitters, paperless recorders, etc.) based in Nanjing, Jiangsu, China. The company publishes technical articles and reference content through its corporate blog to educate and inform customers and industry professionals.
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