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Report on the UH Hydrogen/Oxygen Explosion
Report to the University of Hawaii at
Manoa on the Hydrogen/Oxygen
Explosion of March 16, 2016
Report 1: Technical Analysis of Accident
Prepared by the UC Center for Laboratory Safety, June 29, 2016
Dr. Craig Merlic, Executive Director, University of California Center for Laboratory Safety, Associate
Professor, Department of Chemistry and Biochemistry, UCLA
Mr. Eugene Ngai, President, Chemically Speaking LLC, Whitehouse Station, NJ Dr. Imke Schroeder, Research Project Manager, University of California Center for Laboratory Safety, Adjunct Associate Professor, Microbiology, Immunology and Molecular Genetics, UCLA Mr. Kenneth Smith, CIH CHP, Board Member, University of California Center for Laboratory Safety, Executive Director for Environmental Health & Safety, University of California Page 1 Report on the UH Hydrogen/Oxygen Explosion Table of Contents Executive Summary: Report 1
Introduction and Goals of Investigation
Events Leading Up to the Accident
Safety Considerations in the UH Laboratory
No answers to the researcher’s questions were found and further safety concerns were no longer present in subsequent meeting notes or in the postdoctoral researcher’s laboratory notebooks.
Bacterial Cell Culture in Bioreactors
Use of a Gas Storage Tank to Contain H2, O2, and CO2
Procedure to Fill the Gas Storage Tank with H2, O2, and CO2
Procedure to Remove a Gas Sample for Analysis
Experiments Involving the Gas Storage Tank
Near Miss Incident in theSame Laboratory
Analysis of Events Leading Up to the Accident
Safety Issues Noted with Equipment Used for Explosive Gas Mixture
General Safety Problems in Academic Research Laboratories
Managing Experimental Changes
Hydrogen Gas Safety
Response to Near Miss Event
Accident Description and Analysis
Potential Causes of the Storage Tank Rupture
Potential Causes of the Gas Mixture Ignition
Causality of the Detonation
Honolulu Fire Department Report
Forensic Examination and Testing
Grounding and Bonding
Likely Cause of Detonation
Conclusions on the Accident Event and Cause
Other Accidents Involving Hydrogen
Appendix A: Initialisms and Acronyms
Appendix B: Terminology
Page 2Report on the UH Hydrogen/Oxygen Explosion
Appendix C: Marking and Labeling of Cylinders and Gas Piping
Appendix D: Compressed Gas Safety Standards and Regulations
Federal OSHA Regulations:
International Fire Code
Appendix E: Compressed Gas Safety Guidelines
General Guidelines for Compressed Gas Safety
Guidelines for Cylinder/Pressure Vessel Filling Safety
Appendix F: Forensic Testing Report
Appendix G: Biographies
Dr. Craig Merlic
Mr. Eugene Ngai
Dr. Imke Schroeder
Mr. Kenneth Smith
Page 3Report on the UH Hydrogen/Oxygen Explosion
Executive Summary: Report 1 This is an investigative report of the March 16, 2016 hydrogen/oxygen explosion at the University of Hawaii at Manoa campus (UH), in which a postdoctoral researcher lost her arm and sustained burns to her face and temporary loss of hearing. The postdoctoral researcher was working in a laboratory at the Hawaii Natural Energy Institute in the Pacific Ocean Science and Technology (POST) building.
This investigation was performed by the University of California Center for Laboratory Safety at the request of UH. The University of California Center for Laboratory Safety, in its capacity as an independent third party review team, was contracted to investigate the circumstances that led to this laboratory accident. The investigation included multiple visits to the site of the explosion as well as other UH research laboratories, examination of physical evidence and documents, testing of equipment remaining after the incident, testing of identical equipment, and interviews with UH staff and administrators, Environmental, Health and Safety Office (EHSO) staff, research faculty, graduate students and postdoctoral researchers. The report is separated into two sections. The first report presents conclusions regarding the technical details of the explosion as well as presenting an analysis of its immediate cause. This report also provides an in-depth review of the documentation, physical evidence recovered from the incident scene, a detailed analysis of possible causes and a summary of the forensic testing performed on the equipment involved in the accident. The second report contains recommendations for improvement of the UH research safety operations.
The immediate cause of the accident was traced to the digital pressure gauge which acted as a path to ground for a static charge that ignited the hydrogen/oxygen gas mixture contained within a 13 gallon (50 liter) pressure tank. Extensive analytical testing of an identical gas tank/pressure gauge system did not reproduce a stray electrical current within the digital pressure gauge suggesting that the initiation event was due to a static discharge generated in the tank or the researcher. The explosive gas mixture was most likely ignited when the statically charged researcher touched the metal housing of the gauge and a charge transfer occurred causing a corona or brush discharge within the gauge stem.
While the likely point of initiation of the explosion was determined to be due to static discharge through the digital pressure gauge, it should be emphasized that there are numerous means by which a hydrogen/oxygen gas explosion can be initiated. It is imperative that, hydrogen/oxygen gas mixtures in the explosive range should not be stored, and experiments using hydrogen/oxygen gas mixtures, such as the culture of hydrogen-oxidizing bacteria, should undergo rigorous hazard analysis and mitigation efforts to eliminate possible sources of ignition.
This accident at the UH laboratory showcases once again the challenges that academic research laboratories face in addressing physical hazards of experimental processes and recognizing potential hazardous consequences when experimental procedures are changed. In scientific research the experimental outcome often becomes the driving force and overrides risk considerations. In this respect, the UH lab explosion is similar to the explosion at Texas Tech University and the fire at UCLA. Based on the report of the explosion at Texas Tech University by the Chemical Safety Board (CSB), OSHA has
amended its regulatory standards by establishing non-mandatory recommendations regarding physical hazards in the laboratory including combustible liquids, compressed gases, reactives, explosives and flammable chemicals, as well as high pressure/energy procedures, sharp objects and moving equipment.
The key lessons identified in the CSB report are directly applicable to UH and are included as several of the safety recommendations to UH.
This report was written to serve as a direct call to action for researchers, administrators and EHSO staff not only at the UH, but at all institutions of higher education that conduct research. The recommendations and lessons learned contained herein should be understood and addressed at all universities in order to help prevent laboratory accidents.
29 CFR 1910.1450 Appendix A, https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=10107, accessed 6/2/2016.
Introduction and Goals of Investigation The goal of this investigation was to establish the cause and underlying conditions leading to the explosion that occurred on March 16, 2016 in the Pacific Ocean Science and Technology (POST) building on the University of Hawaii at Manoa (UH) campus. This report provides an in-depth analysis of the events that led to the accident as well as the accident itself to serve as Lessons Learned for academic institutions and other stakeholders that use explosive gas mixtures to advance current technology. Since gas use was so integral to the accident, there is a focus in this report and the appendices on gas safety.
Incident Timeline The Hawaii Natural Energy Institute (HNEI) conducts research on renewable energy sources and energy integration into the grid system. The lab involved in the accident is focused on using hydrogen, oxygen and carbon dioxide for the green production of bioplastics and biofuels. For this purpose the lab works with knallgas bacteria, which are capable of capturing the energy from the reaction between hydrogen and oxygen to fix carbon dioxide into cellular components.
Bacteria were cultured in an open gas system with continuous gas flow. Flow rates of hydrogen, oxygen and carbon dioxide were controlled by mass flow meters, mixed transiently in a gas proportioner and sparged through the bacterial culture. Access gas exited out of the bioreactor into the laboratory fume hood. The lab operated the process since 2013 using various types of bioreactors at 1-3 atm. The postdoctoral researcher involved in the accident entered the lab in October 2015 to develop a closed gas system bioreactor for elimination of gas waste. She was trained in the preparation of gas mixtures using a 1 gallon pressure vessel, which the lab used on a regular basis to supply 70% H2 : 20% O2 : 10% CO2 to small scale liquid and petri dish bacterial cell cultures at a pressure of 2 atm. This setup was used for about 8 months without incident.
The experimental protocol and any necessary changes were discussed in weekly meetings between the postdoctoral researcher and her PI. To streamline the research process using the closed gas system bioreactor they decided to scale-up by pre-mixing the three gases in a 13 gallon gas storage tank. A risk analysis for using the tank with hydrogen and oxygen was not documented. The tank arrived in December 2015 and was leak-tested in January 2016. From the beginning of February until March 16, 2016 the gas storage tank was filled eleven times with varying H2 : O2 : CO2 mixtures, all in the explosive range, with pressures between 37 and 117 psig (1 atm = 14.7 psig). The experiments were reviewed by the PI and the postdoctoral researcher weekly to discuss improvements of the bacterial culture conditions. They assumed the process to be safe since they stayed well below the maximum pressure for which the gas storage tank was rated (140 psig). The lab received a laboratory safety inspection in January 2016, however, the use of the gas storage tank was not questioned because the inspection used a typical checklist focusing on storage of chemicals and chemical waste, gas cylinder storage, laboratory fume hood certification, and documentation of training.
One day before the accident, on March 15, 2016, the postdoctoral research reported a “cracking sound” within the 1 gallon pressure vessel to her PI. The reaction occurred when the postdoctoral researcher depressed the On/Off button of the vessel’s digital gauge. The researcher opened the vessel and discovered that the petri dishes inside were singed and cracked. The gauge had a smaller error range and had been added to the experimental set-up in February 2016; it allowed the researcher to more accurately follow gas consumption by the bacterial cultures over time. The gauge was not rated as intrinsically safe. After reporting the incident, the PI strongly advised the researcher not to use the vessel again.
th On March 16, 2016 the postdoctoral researcher had filled the 13 gallon gas storage tank for the 11 time and was preparing to reconnect it to the bioreactor. As she pushed the On/Off button of the pressure gauge on the tank, it exploded causing severe injuries to the postdoctoral researcher and devastating the lab plus damaging adjacent labs and hallways. The digital gauge on the gas storage tank was of the same model as the one on the 1 gallon pressure vessel.
Weeks before the accident the postdoctoral researcher had also reported to her PI being electrically shocked when touching the pressure vessel and the gas storage tank. Neither the researcher nor the gas storage tank nor the pressure vessel were grounded. There were no blast barriers of any type in place.
Blast barriers are commonly used in chemistry labs working with explosive materials, however, at present they are not commonly used in microbiology labs. The researcher was also not wearing any type of PPE, although due to the force of the blast, this last layer of protection would not have been sufficient to prevent her devastating injuries.
After the accident UH Manoa established a safety committee to review experiments involving highly hazardous substances or processes. The committee is faculty-led and consists of EHSO staff and faculty with expertise in various sectors. Furthermore, HNEI created a Lab Safety Walkthrough guide to assist researchers with laboratory safety compliance such as training and documentation.
Events Leading Up to the Accident The University of Hawaii at Manoa is a public research university and part of the greater University of Hawaii system. It educates about 19,000 students including undergraduate, graduate students and postdoctoral researchers in 20 colleges and professional schools. The Hawaii Natural Energy Institute (HNEI) is part of the School of Ocean & Earth Science & Technology and conducts research on renewable energy sources and energy integration into the grid system. The Institute consists of 35 faculty and all of the Institute’s research laboratories (about 45) are located in the POST building on the main campus. The explosion occurred in one of the POST basement laboratories, Room 30 (POST 30).