An environmentally-controlled extended-use small animal hypobaric chamber.

An environmentally-controlled extended-use small animal hypobaric chamber has been designed to study small laboratory animals at low barometric pressures for long periods of exposure. The rectangular chamber (91.4 X 71.1 X 50.8 cm) is constructed of aluminum plate and acrylic resin with a volume of 3.3 X 10(5) cm3. A computer/data acquisition control unit provides for controlling and collecting data on pressure, temperature, and relative humidity (RH) for sustained operations. Altitude simulation is achieved using a two-stage, air-cooled vacuum pump with a displacement of 30 cm3 X min-1. The pressure within the chamber is controlled by an incremental throttling valve in the vacuum line. Temperature (0-100 degrees C) is accomplished by using a remote-controlled constant temperature circulating bath. RH (20-80%) is regulated by pre-conditioning the ventilation purge air prior to entering the chamber. Acceptable levels of oxygen and carbon dioxide gases are maintained by purging with sufficient volumes of fresh air.