ODH, oxygen deficiency hazard cryogenic analysis

An oxygen deficiency exists when the concentration of oxygen, by volume, drops to a level at which atmosphere supplying respiratory protection must be provided. Since liquid cryogens can expand by factors of 700 (LN2) to 850 (LHe), the uncontrolled release into an enclosed space can easily cause an oxygen-deficient condition. An oxygen deficiency hazard (ODH) fatality rate per hour (OE) is defined as: OE = Σ NiPiFi, where Ni = number of components, Pi =probability of failure or operator error, and Fi - fatality factor. ODHs range from ''unclassified'' (OE<10-9 1/h) to class 4, which is the most hazardous (OE>10-1 1/h). For Superconducting Super Collider Laboratory (SSCL) buildings where cryogenic systems exist, failure rate, fatality factor, reduced oxygen ratio, and fresh air circulation are examined