Cosa 9610

The COSA 9610™ is one of the latest instruments from COSA Xentaur for measuring Wobbe Index, BTU/Heating Value and CARI (Combustion Air Requirement Index).

Calorimeter Measurement Principle (Residual Oxygen Measurement)
The COSA 9610™ Wobbe Index Meter’s measuring principle is based on the analysis of the oxygen content in the flue gas after combustion of the sample. A continuous gas sample is mixed with dry air at a precisely maintained constant ration, which depends on the BTU range of the gas to be measured. The fuel air mixture is oxidized in a combustion furnace in the presence of a catalyst at 800’C, and the oxygen concentration of the combusted sample is measured by a zirconia oxide cell. The residual oxygen provides an accurate measurement for the Combustion Air Requirement (CARI) of the sample gas, which can be correlated accurately to the Wobbe Index of the gas.



Key advantages of this method are its insensitivity to changes in ambient temperature, a very fast response with the ability to measure gases with BTU values down to zero and the measurement of the Combustion Air Requirement Index besides Wobbe Index and Heating Value.

Analyzer Construction

The COSA 9610™ is housed in a painted stainless steel NEMA4X (IP66) cabinet with the dimensions 41” x 41” x 16” suitable for outdoor installations without additional temperature controlled shelter. For extreme climate conditions, the standard operating temperature range of the COSA 9610™ can be extended with the addition of a cabinet heater and/or vortex cooler. The cabinet is suitable for wall mounting or rack mounting.

The analyzer cabinet has three compartments:

  1. The Gas Mixing Compartment: Contains sample condition and the gas mixing system. Components in this compartment are intrinsically safe. The gas mixing compartment can optionally be heated to avoid condensation of heavier gas constituents.
  2. The Electronics Compartment: Contains the industrial PC based controller, which performs all instrument control functions and calculations. Results are available through isolated analog outputs and an LCD, which is visible through a cabinet window and displays residual O2 in %, cell voltage in mV, Wobbe Index and Calorific Heating Value (optionally) in BTU/SCF or MJ/Nm3, relative density (optional), and CARI (Combustion Air Requirement Index).
  3. The Combustion Furnace Compartment: Contains the combustion furnace with the zirconia oxide sensor. The exhaust gas is vented and drained. The electronics compartment and combustion furnace compartment can optionally be purged for Class 1 Div 2 or Class 1 Div 1 applications.


The COSA 9610™ has no moving parts and consequently, maintenance requirements are low. With the use of proper sample conditioning, the COSA 9610™ can operate unattended for several months. All compartments are easily accessible through separate doors on the front side of the enclosure.

The COSA 9610™ Wobbe Index Meter has superseded previous models of calorimeters such as the COSA 9600™ and COSA CW95.


  • High Accuracy
  • Fast Response
  • Large Measurement Range
  • Measures Low BTU Gases
  • Low Maintenance
  • Flameless / No Flameouts
  • Measures Wobbe and CARI
  • IECEX , GOST, FM + CSA & ATEX Certifications Available
  • EPA 40CFR63.670(j) Compliant
  • Direct Measurement Method ( ASTM D-4891 Compliant )
  • Gross or Net Heating Values
  • Ambient Temperature Standard: -40°C to +60°C


  • Turbine Control
  • Flare Stack Control
  • Fuel Optimization
  • Gas Blending
  • Custody Transfer
  • Hyco Plant Control
  • Hydrogen Applications
  • Air Blending Applications



Blending Fuel Gas to Optimize use of Off-Spec Natural Gas

COSA Xentaur BTU History


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