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Video: ‘Straight Talk’ on Gas Flowmeters

Video: 'Straight Talk' on Gas Flowmeters
Video: ‘Straight Talk’ on Gas Flowmeters
This Sierra Instruments video explains the challenges of accurate gas mass flow calculation when a change in pipe direction, shape or size creates a distorted profile. 

Video: ‘Straight Talk’ on Gas Flowmeters


The Sierra Flat-Trak™ Model 780S thermal gas mass flow meter provides a true flat profile and measurement in just two diameters – the shortest pipe run in the industry.

Watch an example of how process fuel or exhaust gas flows through a six-inch pipe with an elbow that creates a complex, unstable profile – making accurate flow rate measurement impossible. One option is to add enough pipe to make this a straight run of 20 diameters for a fully developed flow profile, but it’s still not flat. Adding pipe is costly and takes up valuable space. Flow conditioning is a second option because it eliminates swirl, but extra pipe is still required to remove flow profile distortion.

Sierra Instruments’ thermal mass flow meter with built-in flow conditioning is ideal for gas and electric producers and offers these advantages:

  • Direct mass flow reading
  • One second response
  • Outstanding rangeability
  • No moving parts
  • Low installation cost
  • Certified for Greenhouse gas (GHG) measurement
  • FM, CSA and CENELEC approved for hazardous locations
  • Available for pipe that’s between 2 inches and 8 inches in diameter
  • Optimized for highly accurate and repeatable mass flow measurement of methane (CH4), as well as N20, SF6, HFC’s, PFC’s and CO2

With the Flat-Trak controller, flow disturbances – including a change in pipe diameter or angle – don’t matter. Plus, this air flow sensor eliminates concern about what’s happening upstream. There’s no need for temperature or pressure compensation, and the thermal flow controller requires no downstream straight run. The 780S is routinely used by gas and power plants to measure methane to compressors, pre-heaters, boilers and other process equipment.

This flowmeter’s accuracy is +/ 1% of reading plus +/-0.5% of full scale with repeatability of +/- 0.2% of full scale.

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