1、Lessons Learned Entry: 0550Lesson Info:a71 Lesson Number: 0550a71 Lesson Date: 1997-05-07a71 Submitting Organization: JSCa71 Submitted by: L. H. UnderwoodSubject: Oxygen-Deficient Atmospheres Description of Driving Event: Two technicians were transferring liquid nitrogen from a vendor tanker to a ta
2、nk trailer. Near the end of the operation, visibility was severely limited due to fog caused by venting nitrogen, leading to a decision to shut down the operation until the visibility improved. While shutting down the transfer operation, the technicians became unconscious due to lack of oxygen but r
3、ecovered with no ill effects after being rescued by the tanker drivers. Technicians were wearing PPE for protection against frostbite, spills, etc., but did not include equipment to detect lowered oxygen levels or to supply breathing air.At JSC there are a large number of nitrogen containers. The ar
4、eas surrounding the larger, permanent containers do not normally present pockets in which to trap nitrogen; however, on still days there could be oxygen-deficient areas near the connection the vent, or the 90% fill valve. The smaller portable containers (dewars) could be located in potentially confi
5、ned areas, also presenting the potential for an oxygen-deficient atmosphere.Lesson(s) Learned: Cryogenics are capable of displacing air, resulting in unbreathable, Oxygen-deficient atmospheres.Recommendation(s): 1. Follow your organizations procedures for handling of cryogenics.2. Operations with li
6、quid nitrogen should only be performed using the buddy system and by experienced and qualified personnel familiar with the hazards and safety precautions.3. Resist the urge to rush in and rescue a downed co-worker; 60% of the confined space fatalities happen to the would-be rescuer. If rescue is nec
7、essary, use proper protective/breathing Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-equipment.4. Confined Space Entry requirements and procedures must be followed when working with nitrogen in areas that are not well ventilated.5. Improve visibil
8、ity through the use of portable ventilation fans to disperse the vapor cloud surrounding the operation with necessary.6. Consider use of portable oxygen monitors when working around cryogenic fluids.Evidence of Recurrence Control Effectiveness: Safe Alert 1995 SA95013; NASA-JSC Mishap Report 950045D
9、ocuments Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Cryogenic Systemsa71 Facilitiesa71 Hazardous/Toxic Waste/Materialsa71 Occupational Healtha71 Safety & Mission AssuranceAdditional Info: Approval Info: a71 Approval Date: 1997-05-14a71 Approval Name: Ronald A. Montaguea71 Approval Organization: NA3a71 Approval Phone Number: 281-483-8576Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
