Dirty Little Secret: Gas Composition + Flow Meter Accuracy

April 25, 2019

"A Dirty Little Secret: Case Study on Thermal Flow Meter Calibration for Natural Gas Service" describes the challenges users face when the natural gas composition varies from place to place. A flow meter calibrated for a “standard” natural gas mix may result in compromised flow measurement accuracy if the natural gas composition in the pipe doesn’t match the standard mix the flow meter has been calibrated to measure. This problem can be faced by users across industries in a variety of applications. Any process that involves the use of natural gas can be affected.  This case study can be used as a reference for industry professionals looking to specify flow measurement technology used in the measurement of natural gas and:

  • Changing gas compositions without compromising accuracy
  • Mandated monitoring devices with an accuracy of ±2, ±5, or ±7.5% or better
  • Harsh and remote environments


Fox thermal flow meters are commonly used to provide accurate gas flow measurement for industrial applications. Benefits of Fox meters in these applications include:

  • Gas-SelectX gas selection tool for field-selectable gases/gas mixes without re-calibration at the factory
  • Direct mass flow measurement at very low flow rates
  • Superb turndown for upset conditions - up to 1000:1
  • Accuracy specification that exceeds regulation requirements for monitoring devices
  • In-situ Calibration Validation for mandated verification of device calibration
  • Easy to install – insertion and inline styles available
  • Rugged, low-maintenance design - available with remote sensors


Fox thermal mass flow meters provide the real-time measurement required for sophisticated combustion control systems, as well as other critical flow measurement applications. These include compressed air metering, wastewater aeration, hydrogen monitoring, landfill gas monitoring, purge monitoring, and the measurement of flare, combustor, vent and natural gases.


Download the Case Study below.