REG NASA-LLIS-0945-2001 Lessons Learned Unexpected reactions in chemical mixtures during storage.pdf

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1、Lessons Learned Entry: 0945Lesson Info:a71 Lesson Number: 0945a71 Lesson Date: 2001-06-25a71 Submitting Organization: JSCa71 Submitted by: M. L. MurphySubject: Unexpected reactions in chemical mixtures during storage Description of Driving Event: A tightly capped bottle containing dilute aqua regia

2、chemical waste was stored in a fume hood. Evolved gases resulted in a pressure build-up causing the bottle to explode. The contents sprayed across the room onto the floor. The bottle explosion occurred overnight when the laboratory was unoccupied; however, a potential acid burn exists if an employee

3、 was in the room at the time of the bottle explosion.A review of available literature indicates that aqua regia, which is a combination of hydrochloric acid and nitric acid, will oxidize with time resulting in the evolution of Nitrous Oxide (NO2). This reaction is ongoing and is subsequent to the in

4、tended use of the mixture. This pressure build-up is normal for this type of mixture.Lesson(s) Learned: Understand the physical characteristics of any chemical mixture and implement appropriate safety measures to preclude undesirable events.Recommendation(s): 1. Review the written procedures and the

5、 laboratory Chemical Hygiene Plan for the task.2. Perform job hazard analyses for all laboratory tasks.3. Wear protective clothing (goggles, gloves, coat) and work in a clean well-ventilated fume hood.4. Keep the sash down when reactions are in progress. Never take aqua regia out of the hood.5. Only

6、 prepare the amount you need for immediate use and destroy any excess in the hood in which it was prepared.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-6. Aqua regia can be destroyed by cautious and careful dilution with water. Use a large waste c

7、ontainer and add the aqua regia to the water, which will produce a less hazardous and less reactive waste.7. Never store aqua regia and never put it in a closed container, since evolved gases will cause a pressure build-up and possible explosion.8. Label waste container to remind employees of specif

8、ic waste.9. Schedule a frequent waste pickup disposal. This will prevent overfilling of the container and will promptly remove the hazard from the work area.10. Assess the physical characteristics of any mixture through literature searches, professional consultation, or direct test/check out of the

9、mixture both prior to and subsequent to loading the reaction system especially for the first time.11. Be aware of the limitations of relying on material safety data sheets (MSDS) and other literature to assess the hazardous characteristics of a mixture. MSDS do not traditionally address interactions

10、 between a mixtures chemical components except as broad classes (acids versus bases, oxidizers versus reducing agents, or organics, etc.).Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Disposala71 Facilitiesa7

11、1 Hazardous/Toxic Waste/Materialsa71 Occupational Healtha71 Packaging Handling Storagea71 Personal Protective EquipmentAdditional Info: Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Approval Info: a71 Approval Date: 2001-07-10a71 Approval Name: Eric Raynora71 Approval Organization: QSa71 Approval Phone Number: 202-358-4738Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-