What is the difference between Coriolis and ultrasonic flow meters?

Coriolis meters measure mass flow directly by detecting tube oscillation frequency changes caused by the Coriolis effect. They offer high accuracy (typically +/-0.1% for liquid, +/-0.35% for gas) and high turndown (100:1). Ultrasonic meters measure volumetric flow by timing ultrasonic pulses traveling with and against the flow. They are non-intrusive, offer wide rangeability (20:1 to 50:1 with multi-path designs), and are preferred for large line sizes (6 inch and above).

When should I use a Coriolis meter versus an ultrasonic meter?

Use Coriolis meters for: liquid custody transfer (crude oil, NGL, condensate), small to medium line sizes (up to 12 inches), applications requiring direct mass measurement, and high-accuracy bi-directional flow. Use ultrasonic meters for: gas custody transfer in large pipelines (6 to 48 inches), applications where minimal pressure drop is critical, wet gas or dirty gas service, and when non-intrusive measurement is preferred.

What are the upstream piping requirements for ultrasonic meters?

Per AGA Report No. 9, ultrasonic meters typically require 10 pipe diameters of straight run upstream and 5 diameters downstream without a flow conditioner. With an approved flow conditioner (tube bundle or CPA 50E), the requirement reduces to approximately 5D upstream and 3D downstream. Multi-path meters (4+ paths) are less sensitive to flow profile disturbances than single or dual-path designs.

Coriolis / Ultrasonic Meter Sizing Calculator

Meter Configuration

Meter Type

Fluid Type

Accuracy Requirement

Flow Conditions

Normal Flow Rate

MMSCFD

Minimum Flow Rate

MMSCFD

Leave blank to auto-calculate from turndown ratio

Maximum Flow Rate

MMSCFD

Leave blank to use 1.5x normal flow

Operating Conditions

Operating Pressure

psig

Operating Temperature

°F

Line Size (NPS)

Gas Properties

Gas Specific Gravity (Air = 1.0)

Gas Z-Factor

Leave blank to auto-estimate from SG, P, and T

Viscosity

Liquid Properties

Liquid Density

lb/ft³

Crude ~52, NGL ~35, Water ~62.4

Viscosity

Design Parameters

Allowable Pressure Drop

psi

Required Turndown Ratio

Path Configuration (Ultrasonic)

Flow Meter Selection Guide

Coriolis Meters
Direct mass measurement via tube oscillation. Best for liquid custody transfer (crude, NGL, condensate), small-medium lines (up to 12"). Accuracy: ±0.1% mass (liquid), ±0.35% (gas). Turndown: 100:1.

Ultrasonic Meters
Transit-time volumetric measurement. Best for gas custody transfer in large pipelines (6"-48"). Non-intrusive, negligible pressure drop. Multi-path designs (4+ paths) for custody transfer per AGA 9.

Key Standards: API MPMS Ch. 5.6 (Coriolis), AGA Report No. 9 (Gas Ultrasonic), AGA Report No. 11 (Coriolis for Gas), OIML R 137 (Ultrasonic Gas Meters)

📚 Learn the Theory

Understand the Coriolis effect, ultrasonic transit-time principle, custody transfer requirements, and AGA standards

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Results

Recommended Meter Size

Normal Velocity -

Min Velocity -

Max Velocity -

Pressure Drop (Max Flow) -

Reynolds Number (Normal) -

Accuracy Class -

Available Turndown -

Mass Flow Rate -

Actual Volume Flow -

Speed of Sound -

Recommended Paths -

Upstream Straight Run -

Downstream Straight Run -

Formula

v = Q / A_meter

v = Flow velocity through meter (ft/s)

Q = Actual volume flow rate (ft³/s)

A = Meter cross-sectional area (ft²)

ΔP = K × ρ × v² / 2 (pressure drop)

Re = ρ × v × D / μ (Reynolds number)

Standards & References

API MPMS Ch. 5.6
Measurement of Liquid Hydrocarbons by Coriolis Meters
AGA Report No. 9
Measurement of Gas by Multipath Ultrasonic Meters
AGA Report No. 11
Measurement of Natural Gas by Coriolis Meter
OIML R 137
Gas Meters (Ultrasonic)
ISO 17089
Measurement of Fluid Flow — Ultrasonic Meters

Engineering Notes

Coriolis accuracy: ±0.10% mass for liquid, ±0.35% for gas (custody), ±0.50% volume
Ultrasonic accuracy: ±0.5-1.0% (4-path custody), ±2% (1-path process)
Gas velocity range (USM): 3-100 ft/s operable, 15-70 ft/s optimal
Coriolis turndown: Up to 100:1; ultrasonic typically 20:1 to 50:1
Upstream piping (USM): 10D without conditioner, 5D with flow conditioner
Noise: Avoid placing ultrasonic meters within 20D of control valves

Quick Reference — Meter Sizes

Coriolis: 1/2", 1", 2", 3", 4", 6", 8", 10", 12"
Ultrasonic: 2", 3", 4", 6", 8", 10", 12", 16", 20", 24", 30", 36"
Meter may be smaller than line size (use reducers)
Multiple parallel runs for very high flow

Coriolis / Ultrasonic Meter Sizing Calculator

Meter Configuration

Flow Conditions

Operating Conditions

Gas Properties

Liquid Properties

Design Parameters

Flow Meter Selection Guide

📚 Learn the Theory

Results

Formula

Standards & References

Engineering Notes

Quick Reference — Meter Sizes

Related Calculators

Orifice Meter

Line Sizing

Gas Density

Gas Velocity