Heat release rate measurements of thin samples in the OSU apparatus and the cone calorimeter

The Ohio State University (OSU) apparatus and the cone calorimeter are two devices commonly used to measure the heat release rate (HRR) of materials and products in forced flaming combustion. Each operates on a different principle but is calibrated in the same way. However, HRR results from these two test methods do not agree in most cases. For the present study, the OSU was modified to measure oxygen consumption and sensible enthalpy (temperature rise) of the apparatus in addition to the usual sensible enthalpy of the exhaust gases during the test. After calibration, total sensible heat (exhaust gases+apparatus) and oxygen consumption methods gave similar results for thin samples in the OSU. However, OSU results for thin samples did not agree with results from the cone calorimeter (ASTM 1354/ISO 1556) unless the HRR history in the cone calorimeter was corrected for smearing that results from dilution of the combustion gases with air in the sample chamber, exhaust duct, and scrubbers and the response time of the oxygen analyzer.