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Exhaust Mass Flowmeter


Raw Exhaust Mass Flow Meter

Discover the benefits of direct in-situ exhaust measurement with ExhaustTrak. With our roots in flow measurement and automotive test, Sierra has developed ExhaustTrak, an innovative spin on a centuries old flow meter technology that solves one of today’s greatest flow measurements challenges.

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Key Benefits

  • Go direct to the sample zone 
  • Innovative pressure averaging rings eliminate contamination issue
  • Eliminating need for chemical mass balance methods
  • Resolves temporal offset & instantaneous emissions error contributions vs. intake mass sources
  • Reduced straight length requirements
  • Meets or exceeds US EPA 40 CFR Part 1065 
  • Fuel H/C input, direct O2 measurement capability allows for molar weight compensation


Venturi Size - 1-inch to 8-inch OD Standard Absolute Pressure: up to 200 kPa Standard
Tempeature: up to 950°C Standard Maximum Flow Rates (500°C, 1 atm):
50 kg/hr - 6000 kg/hr Standard

exhaust trak comparison chart

exhaust trak venturi flow body

inside exhaust trak

Challenges of Direct Exhaust Measurement

  • Hight Temperature
  • Moisture
  • Pulsations
  • Turndown 
  • Pressure Drop
  • Particle-Laden Gases

The Indirect Solution

  • Current indirect methods of exhaust flow measurement are fraught with uncertainty.
  • Most common method estimates the flow using direct engine inlet air mass flow and chemical balance derived fuel mass to time-aligned gaseous emissions concentrations. 
  • This method is complicated
  • Most importantly, it has little room for improvement in measurement accuracy and repeatability

Why Measure Exhaust Direct?

  • Exhaust flow measurement, a critical input to emissions sampling
  • Only solution to improve accuracy and repeatability
  • Lower cost, real-time
  • Legal and accurate
  • Best for transient partial flow dilution proportional sampling
  • Eliminate flow-related bias
  • No sensitivity to upstream pneumatic capacitance
  • Best option for raw transient emissions measurement
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