visual inspection of the sample during the test. Reach-in chambers provide an opening that technicians may use to handle test samples. Chambers providing interior visual lighting must take into account the heat generated and compensate accordingly. As with the wide variance in size, a number of user control options are available, ranging from simple analog indicators up to more modern digital readouts with LCD displays. Chambers may be computer programmable, and networked or Web-enabled test chambers with built in web servers are also available. Types of test chambers Mechanically cooled test chambers Liquid nitrogen cooled test chambers Modular Walk-in Chambers Test chamber standards Several standards organizations provide standards and guidance on environmental test chamber construction, temperature control standards, and engineering tolerances. Institute of Environmental Sciences and Technology Air Conditioning, Heating and Refrigeration Institute (formerly the American Refrigerant Institute) American Society of Heating, Refrigerating, and Air-Conditioning Engineers Air conditioning#Heating ASTM International Underwriters Laboratories NSF International FM Global Canadian Standards Association International Organization for Standardization MIL-STD-810, "Test Method Standard for Environmental Engineering Considerations and Laboratory Tests", presently (2010) version G, issued in 2009 IEC 60068, "Environmental Testing", with many parts. See also Cyclic corrosion testing Salt spray test Environmental stress cracking Doriot Climatic Chambers Accelerated aging Environmental stress screening Environmental stress fracture MIL-STD-810, DoD Standard for Environmental Engineering Considerations and Laboratory Tests Shelf life Standard conditions for temperature and pressure Thermo-mechanical fatigue test Universal testing machine Weather testing of polymers Stabilizers for polymers References Tests Environmental testing