Cryogenic safety and hazard management in Air Separation Unit

Cryogenics is growing into a major aspect of many fields of engineering and science. The use of cryogenic liquids in large and small quantities entails potential hazards. It becomes increasingly important to be aware of the potential hazards, when working at low temperatures. Air Separation Units for liquid nitrogen production at various Heavy Water Plants, Heavy Water Clean - UP project at HWP-Kota, Liquid Helium plant for supplying liquid helium used in cryostat with super conducting coils of main magnet assembly at VECC are certain cryogenic systems handling cryogens in units established under Department of Atomic Energy (DAE). While most of the low temperature liquids and solids may be harmless by themselves, their careless and thoughtless use may give rise to very serious consequences. The intent of this article is to provide a helpful overview of the major hazards, proper handling methods and proper storage of cryogenic fluids. The hazards associated with these products are many and varied. More than one hazard is often present in a single product. For example, liquid oxygen combines the oxidizer, extreme cold and high concentration hazards. Cylinder hydrogen combines the high pressure and flammable hazards. HEWAC facility at HWP-Kota comprising of various sections has operating pressures in the range of 1 Kg/cm2 to 150 Kg/cm2 and temperatures in the range of 308 K to 20 K. This facility has combined hazards associated with hydrogen, high pressure systems related to nitrogen refrigeration system and radiation hazards. A clear understanding of all hazards associated with the gases, as well as safe handling and storage methods, will reduce the likelihood of accidents and injury. The paper also attempts to highlight the hazards in Air Separation Units (ASU). (author)