Coriolis meters can measure gas mass flow directly, but gas service needs careful sizing because gas density is much lower than liquid density. A suitable choice depends on the actual operating pressure, temperature, composition and flow range, along with the allowable pressure loss.
When Coriolis can make sense
Consider Coriolis when the process needs direct mass-flow measurement, compact installation, or simultaneous density information and the required capacity fits an available meter. Examples may include controlled gas dosing, pilot processes, specialty gases and selected higher-pressure applications. Confirm the specific meter's published gas-service limits with the supplier.
For large gas volumes or low-pressure service, the required meter size and pressure drop may make another technology more practical. Thermal mass, differential-pressure, vortex or ultrasonic meters may suit some duties better. Compare technologies against the measurement objective, available straight run, turndown, gas composition and maintenance constraints.
Provide operating data, not just the pipe size
For an initial sizing review, provide the gas composition or identity, minimum/normal/maximum mass or volumetric flow, operating and design pressure, operating temperature, and the reference conditions used for any standard-volume flow value. Also state whether the gas may contain liquid, condensate, particulates or changing composition.
If the flow is specified in Nm³/h or SCFM, identify the reference temperature and pressure. Standard-volume values depend on those reference conditions; they should not be treated as the actual volume inside a pressurized line.
Check pressure drop and meter capacity
Ask the supplier to size the meter at minimum, normal and maximum flow using the actual pressure, temperature and gas properties. Review expected pressure loss across the complete operating range and compare it with the process allowance. A meter selected only by nominal pipe size can be inaccurate at low flow or create unacceptable pressure drop at high flow.
Confirm the specified accuracy basis and operating range for gas service rather than assuming liquid performance figures apply. Include any required turndown, repeatability, response time and density measurement in the acceptance criteria.
Plan the installation and signals
Follow the manufacturer's orientation and piping instructions. Keep the line appropriately supported, minimize vibration and avoid arrangements that allow liquid to collect in the sensor. Check the available face-to-face length, reducer design, isolation valves, maintenance access and transmitter location. Coriolis meters often have less straight-run sensitivity than some velocity meters, but they still require a mechanically sound installation.
Specify the outputs required by the control system, such as 4-20 mA, pulse, HART or Modbus, and identify any hazardous-area classification. Verify process connections, wetted materials, pressure rating, ambient limits and the applicable approvals against the complete instrument configuration.
Gas application checklist
- Gas identity or composition and any expected composition changes
- Minimum, normal and maximum flow, with reference conditions for standard volume
- Operating/design pressure and temperature
- Allowable pressure drop and required accuracy across the flow range
- Moisture, condensate, particles or possible two-phase conditions
- Pipe size, connection, installation space, outputs and area classification
Send these details with the destination market and required certificates so the meter size, pressure rating and documentation can be reviewed together. A technical sizing check should confirm whether Coriolis is a good fit or whether another meter principle is more appropriate.
Request a Gas-Service Sizing Review Read the General Selection Guide
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