A combined environmental test chamber integrates several environmental functions in one machine. It is used in aerospace, materials and instrumentation, among other fields, and is built to keep working under fairly harsh conditions. Its manufacturing features show up mainly in the structure and the refrigeration system.
Structure
The outer shell is made from galvanised steel sheet, finished with electrostatic powder coating. The inner chamber uses brushed stainless steel with full-penetration argon-arc welding, which limits leakage and permeation of hot, humid gas. The inner liner has rounded corners so that condensation on the side walls drains away.
Refrigeration
Refrigeration uses a standardised, factory-built system that is pressure-held with nitrogen for 24 hours to confirm there is no leak. Piping follows a controlled steel-tube process, with welding and routing carried out to standard so that the system stays stable and reliable. Copper tubes are bent as a single length on the tube bender, which lowers flow resistance during operation and lets the system run at a stable pressure.
Because a combined chamber reproduces the temperature and humidity changes a part sees in transport and in service more closely, the simulation is closer to reality and testing is more efficient — one reason the design is widely used.