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

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