The AC500 determines calorific value, a key indicator of quality and value in solid and liquid fuels, through measurement of the heat released after combustion of a sample. This stand-alone benchtop unit uses a fully-integrated circulation system for a compact footprint—no additional heaters or coolers required. An integral water-measuring station simplifies sample preparation, and a Windows®-based operating system uses an electronic thermometer accurate to 0.0001°C to measure temperature every six seconds. Two-channel correction is possible through constant temperature monitoring in both the outer jacket and the calorimeter proper.