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Controlling Natural Gas Usage Costs

FlatTrak 780S Thermal Inline Mass Flow Meter

A large American engine manufacturer required mass flow meters to measure natural gas usage in each of the eleven buildings on their campus. Natural gas is used to fire furnaces and other equipment. Because each facility is a separate profit center, fuel and utility costs are allocated by building. They must also provide an accurate usage report of natural gas to the Department of Natural Resources (DNR) for emissions compliance. The DNR uses furnace temperature, excess oxygen and actual boiler-operating information to calculate NOx emissions from natural gas fired boilers.

The utility engineers had identified several problems with their system, not the least of which was the high maintenance requirement of their turbine meters. They were looking for a replacement technology that would give them a direct reading of mass flow, reduce maintenance and fit the "footprint" of the turbine meters.


Challenged by a highly constrained piping system that did not provide the required upstream diameters for most thermal mass meters, they selected Sierra’s FlatTrak™ 780S thermal inline mass flow meter, which provided the necessary solution and perfectly fit the footprint of the turbine meter.

The meter incorporated Sierra’s unique dual-plate flow conditioning element to eliminate velocity profile distortions as well as swirl and temperature stratification in the gas stream. It reduced piping straight run requirements to as little as three upstream diameters.  As a result, they saved money on installation costs when compared to an orifice-plate where at least 20 upstream piping diameters are required for optimal performance.

The accurate fuel flow measurements provided by the 780S immediately helped the operators adjust boiler variables to reduce NOx emissions. The meter's wide turndown provided an accurate measurement of natural gas at low and varied loads, ensuring accurate cost-allocation and improved boiler control capability. The transducer's smart electronics and field-validation capability have also simplified auditing procedures for emissions compliance.

Here’s what makes Sierra’s FlatTrak 780S an ideal choice:

  • Measures mass flow directly with one meter
  • 100:1 turndown for accurate monitoring of peak and low flow situations
  • In-line flow conditioning eliminates piping straight-run requirements
  • Removable probe for easy cleaning
  • Generates minimal pressure drop across the instrument
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