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Electrolysis
During the process of electrolysis, using closely positioned electrodes (made of various metals) in an electrolyte solution into which an electrical current is introduced produces gas bubbles in the water. Oxygen is formed on the positive electrode; hydrogen is formed on the negative electrode. The mixed gas produced contains two parts hydrogen and one part oxygen. This mixed gas is extremely sensitive and can explode with the smallest amount of friction or a tiny spark. Through the years, there have been numerous occurrences in which people have attempted to package this gas and have incurred severe injury or have died.
Another process for forming a flammable gas is to generate an arc under a nonelectrolyte solution, creating hydrogen and carbon monoxide with a smaller amount of carbon dioxide and other trace gases. In this mixture, oxygen is not a component, which limits the danger of an accidental explosion. But, when this gas is compressed, water vapor becomes a serious issue and causes stress corrosion cracking in the cylinder (from carbon dioxide/carbon monoxide and water).
These are the most common ways to produce a usable fuel, but there are other ways as well. It is much more expensive to produce hydrogen-based fuel than it is to purchase fossil fuel. The estimated cost of producing a hydrogen-based fuel is usually four times that of producing a fossil fuel. With all of this said, home hobbyists and inventors are working each day to discover a better way to produce nonfossil fuels at great risk to the public and emergency responders.
Causes of Stress Corrosion Cracking (SCC)
Stress corrosion cracking (SCC) is caused by the cylinder’s makeup and construction and chemical reaction.
- Cylinder makeup and construction. This phenomenon occurs over a very broad range of carbon dioxide (CO2)/carbon monoxide (CO) and water ratios; however, stress (pressure) assists in the process of micro-crack development. Low-alloy steel (steel that has a low percentage of chromium, molybdenum, manganese, nickel, as examples) under pressure in the presence of CO2/CO and water develops micro-cracks.
- Chemical reaction. Within the cylinder the CO2/CO and water mixture create a mild acid that infiltrates the metal, causing the micro cracking to occur. Oxygen and sulfur that may be present within the gas mixture can accelerate the phenomenon.
It is believed that both of these processes are occurring and are causing the SCC that resulted in catastrophic failure of the steel cylinder. Cracking decreases as the temperature increases. Once the damage is done, any movement can result in cylinder failure; this would/could include opening the valve.
Experimental Gas Cylinder Failure: Incident Report
BY ROBERT COSCHIGNANO AND EDWARD J. MAERKL
On September 26, 2013, at approximately 1230 hours, the Orlando (FL) Fire Department was dispatched to reports of an explosion in the downtown corridor. Units arrived to find a huge hole (approximately 50 feet wide) (photos 1-2) in the brick wall in the rear of the building in question. The building was an approximately 38,000-square-foot, warehouse-type structure with a combination of construction styles, including steel I-beam, terra-cotta block, and wood floor and substructure.
(1-2) Photos, except photo 3, by Robert Coschignano, Orlando (FL) Fire Hazmat. |
The first-due district chief arrived, established command, and implemented a National Incident Management System command structure. Command allocated units by task. Special operation units, Engine 101, Hazmat 1, and Tower 7 were assigned to collaborate and form the Hazardous Materials group. Heavy rescue evaluated the structure for stability and established a proactive rapid intervention team (RIT). Tower Company 1 was tasked with controlling utilities; Engine Company 1 established a supply line and protection lines in case of fire or secondary explosions. Rescue 1 would become the ready rescue should victims be found or firefighters injured. The second-arriving district chief became the safety officer.
Several other units responded initially; they primarily assisted in establishing a safe zone and denying entry to civilians; the police department eventually took over these functions. The nearby railroad had to be shut down because units were staged too close and supply lines crossed the tracks. Railroad supervisors were integrated into a unified command structure, as was a public information officer, as the interest of the media and several nearby federal offices was mounting. The department’s Arson/Bomb Squad began interviewing eyewitnesses and the building owner and staff.
SIZE-UP
Early on, a clear path of destruction was prominent on the ground floor B-C quadrant, which was a suspected area of origin. We inspected the basement for victims, damage to below-grade structural components (floor joists, for example), and hazardous atmospheres; nothing was found.
On the ground floor, there was heavy destruction; however, no fire damage was present, which you would expect when a natural gas leak finds an ignition source. Various large pieces of equipment and several red 150-pound type pressure cylinders were scattered throughout the debris outside and in the room of origin.
The Arson/Bomb Division reported, after speaking with the building owner, that he was working with an experimental gas he called carbohydrillium, used for cooking and industrial purposes. Units withdrew from the building at this time. The hazardous materials officer (E101 officer) met with the building owner and his “scientist.” They reported that there was not a proper safety data sheet (SDS) and that the exact chemical formula for this mixed gas was unknown. They provided some approximate values of gases contained in the product and described the general procedure for making it.
From the interview, we learned that the mixture contained oxygen, carbon monoxide, carbon dioxide, nitrogen, and hydrogen in undetermined levels. Other compounds present included acetylene, methane, ethylene, ethane, propane, propylene, and other light-chain carbon compounds. The owner reported that he had experienced some previous “minor” tank failures in past months.
Further investigation conducted in the area of origin determined that what had initially appeared to be a flat piece of pitted steel was what remained of the completely failed pressure cylinder (photo 3). Debris hid the cylinder valve assembly, making the cylinder difficult to recognize.
(3) Photo by John Jockin/Ron Verbal, Orlando Arson/Bomb. |
MITIGATING THE CYLINDER THREAT
Command met with the bomb squad and the hazmat team to establish an action plan. It was determined that the remaining cylinders posed a potential safety hazard that needed to be mitigated. The discussion was focused on the best method for dealing with the remaining cylinders, which numbered about 10. The owner provided a sketch of where the full and empty cylinders were originally located; it was of little help since the explosion had moved nearly all of them. The owner did not document them as full or empty.
Ideally, the use of the explosive ordnance disposal robot would have been the first choice since it was an unstaffed operation. However, the Bomb Squad did not feel the robot could effectively maneuver in the debris (photo 4).
The second option was to use a bomb technician in a blast suit. This option was debated, as there was concern that the lack of vision and mobility in the suit when the technician moved over and around the debris might present hazards.
The final decision was left to the hazardous materials team (HMT), which decided that a two-person team using bunker gear with self-contained breathing apparatus, air-monitoring detection, and an unstaffed rapid attack monitor (RAM) nozzle would enter to hydraulically ventilate the gases out through the breach in the wall and provide some protection to the operating crew in case of a failure or fire. A RIT and Ready Rescue would be on standby.
The first steps were to set up the unstaffed monitor and move the bomb robot into a position to monitor sound and video for the room so the entry team and cylinders could be observed. A two-person entry team entered the structure and proceeded to the first cylinder. Each bottle was marked with a number, the crew name, the date, and the time in a conspicuous place so we could keep track of how many bottles were rendered safe. The entry team encountered the first bottle, uncapped it, and cracked the valve to begin the venting process. It then withdrew, activated the hydraulic RAM nozzle, and made its way to a preidentified safe refuge area. A four-gas monitor with a photoionization detector was within ear and eye shot of the robot camera to document readings of the gases. Alarm levels on both carbon monoxide and lower explosive level (LEL) were noted (with no fog line LEL 72% CO 35%, under fog line LEL1-5% CO 2%). Once complete, the RAM was secured and moved to the next cylinder. This process was repeated for all 10 cylinders; the HMT made multiple entries. The HMTs created a map that listed the locations of all of the cylinders handled; it was passed along so that each team could start where the other left off. All the cylinders were safely bled off without incident. Incident operations continued for approximately seven hours.
LESSONS LEARNED
Several lessons were learned from this incident:
- The safety of personnel and the public is the number one consideration.
- A strong interagency unified command system is imperative. It contributed to the overall success of this incident.
- Gain intelligence from a variety of sources, including the owner/occupant of the building, if possible.
- Conduct a risk-vs.-gain analysis, and establish an incident action plan.
- Rotate crews to prevent fatigue and provide adequate rehab.
- Resist the pressure to open highways, railways, or other traffic avenues until the incident allows.
- This variety of experimental cooking gas is gaining popularity all over the United States and appears to be held to little regulation.
ROBERT COSCHIGNANO has been with the Orlando (FL) Fire Department for 20 years and is a lieutenant on its hazardous materials team.
EDWARD J. MAERKL has been with the Orlando (FL) Fire Department for seven years and is a firefighter/paramedic on its hazardous materials team.
RICHARD STILP is a retired chief officer from the Orlando (FL) Fire Department, where he served as a paramedic, hazmat team member, hazmat company officer, and hazmat chief officer. Since retirement, he has served as the corporate director of safety and security for a large health care organization in Central Florida, executive director of the Central Florida Fire Academy, and hazardous materials coordinator for Florida Region 5. He is an author, has served on several federal committees, and is active in local planning and emergency management in Central Florida.
ARMANDO BEVELACQUA is a retired chief officer from the Orlando (FL) Fire Department, where he served as a paramedic, hazmat team member, hazmat company officer, and special operations chief. Since retirement, he consults and teaches across the nation in the areas of emergency preparedness, incident command, and hazardous materials. He is an author and serves on a number of federal committees.
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