MODIFICATION, OPERATION, AND ERROR ANALYSIS OF AN INDIRECT CALORIMETER FORWITHIN-CHAMBER CONTROL AND DATA ACQUISITION

An existing environmental chamber for short-term indirect calorimetric studies was re-configured for use as a within-chamber recirculation unit with a computerized control and data acquisition system, and modified with an in-chamber humidity control unit to provide 30 to 80% RH. Intake air was pre-conditioned to a specific temperature-humidity state point and delivered at 20 to 50 standard L/min. Data can be collected from the chamber to a computer via an 8 channel amplifying/filtering unit and an analog-digital converter. The computer also controlled the environmental conditions in the chamber. Over a series of “dry” runs (without animals), system error for dry bulb temperature varied from ± 0.2°C to ± 1.1°C, with an average error of 0.4°C. Average moisture production and CO2 errors were 6.5% and 1.4%, respectively, from a series of animal tests. All were within acceptable limits for reliable data generation.