Ice & Oxygen Create Hazmat Problem In Iowa

An unexpected storm during the early-morning hours of Dec. 7, 2000, blanketed much of eastern Iowa with a paralyzing coat of ice, creating a traveler's nightmare. Slick conditions from the storm caused three tractor-trailer trucks to pile up just west of the Interstate 80 and Interstate 380 intersection near Iowa City.

The aftermath of the accident left emergency responders grappling with hazards from, of all things, the life-sustaining element of oxygen.

The incident occurred within the Oxford Fire Department district, one of the more than 800 volunteer fire departments providing fire and emergency protection to Iowa's predominantly rural population.

Oxford Fire Department personnel were summoned to the incident at 6:30 A.M., simultaneous with an alarm for another accident on the interstate. Fire Chief Mark Hora dispatched firefighters to both of the incidents and requested assistance from the Tiffin Fire Department, eight miles away.

On arrival at the other incident three miles from the truck accident, firefighters found a fender-bender with no personal injuries. They then went to the scene of the truck accident.

While enroute to the truck accident five miles from the Oxford station, Hora was notified that one of the vehicles was a tanker. He immediately requested assistance from the Johnson County Hazardous Materials Response Team stationed at Iowa City Station 2, about 10 miles from the incident. The team is composed of 25 career and volunteer members from Johnson County fire departments.

Bad roads limited the team's hazmat van to speeds of 25 mph or less and delayed arrival of the van and equipment under command of Iowa City Firefighter Paul Suedkamp until 8 A.M.

When he arrived on the scene, Hora found that the three trucks had piled against each other in the grass median strip between the two lanes of the interstate. He identified a placard on the tanker truck bearing the number 1073 - liquefied oxygen (LOX). The tank was overturned onto its top. A small vapor cloud was rising from the tank.

Hora was also given shipping papers from the LOX tanker by Johnson County Hazmat Team member Paul Millice. Millice obtained them from the truck's driver, who was uninjured and out of the truck. The truck was owned by Cryogenic Transportation Inc. in Omaha, NE.

Assessment of the situation by firefighters discovered that the driver of the second truck carrying auto parts, owned by J.B. Hunt, was also free from the wreckage. Donald Ray Allen, driver of the third truck, an Arctic Express Trailer carrying fresh fruit, was pinned inside his vehicle between the other two.

Hora ascertained that vapors escaping from the Cryogenic tanker were blowing away from the trucks and the pinned victim. He ordered a rapid extrication of Allen. Firefighters accomplished the task in 10 minutes, then backed away from the wreckage.

In the meantime, Hora requested that the Iowa Department of Transportation (DOT) close down both lanes of the interstate. The DOT complied with the request and diverted traffic to other routes. The interstate remained shut down for 10 hours until 4:30 P.M. Allen was transported to a hospital in Iowa City, suffering from a broken neck, ankle and forearm.

Hora contacted Cryogenic and was told to open a ventilation valve on the truck, which he had two firefighters make entry and do. He was advised to do this because of concerns that pressure inside the tanker would build to dangerous levels. Vapors from the LOX that is transported and stored at minus 297 degrees Fahrenheit normally vent off through a valve and pressure relief system. The tanker was upside down, which was thought to make the ventilation system inoperative, thereby causing the vapors to increase pressure inside the tank.

Once Suedkamp and the Johnson County Hazmat Team were on scene, he moved the Oxford firefighters back from their location within 30 feet of the Cryogenic trailer to a position 300 feet away as recommended in the 2000 Emergency Response Guidebook. In so doing, Oxford firefighters abandoned an engine that was parked close to the accident.

From that point, emergency responders were sequestered to waiting for Cryogenic company officials and heavy equipment to arrive on scene. The tanker was later set on its wheels using cranes and towed away.

Hora had a school bus brought to the scene for emergency responders to stay in during the long wait. At 27 degrees, this was also one of the coldest days of the year so far.

Emergency responders operated with all due regard for safety in this incident by conducting a rapid extrication and withdrawing a safe distance away. However, the nature of hazards associated with LOX point out how contrary the element can be to its normally harmless, life-sustaining state.

Ken Humphries, safety director for Cryogenic, explained that LOX itself presents three safety hazards to emergency responders:

1. As a cryogenic liquid, LOX is stored at a temperature of minus 297.35 degrees Fahrenheit. Contact with the cryogenic liquid or cold piping containing the liquid can cause tissue freezing or frostbite on dermal contact or if splashed in the eyes.
2. Breathing high concentrations of LOX (greater than 75 molar percent) causes symptoms of hyperoxia, which include cramps, nausea, dizziness, hypothermia, ambylopia, respiratory difficulties, bradycardia, fainting spells and convulsions capable of leading to death. In general, pure oxygen is a local irritant to mucous membranes and, with extended continued exposure, can be destructive to lung tissue.
3. LOX splashed onto an emergency responder's clothing or protective gear, or an emergency responder coming into contact with a LOX vapor cloud can cause the emergency responder's clothing to become oxygen-saturated. The danger with such a situation is that if they were to contact an ignition source, there could be a flash fire resulting in severe flesh burns or death.

LOX will vaporize slowly once it is introduced into the atmosphere. The fact that this occurs slowly, and not immediately, gives occasion for other hazards while the product remains in its liquid state. Oxygen will react with most materials in one way or another, and this creates special concerns. All easily combustible materials, especially hydrocarbon oils and greases, must be kept from contact with products with high oxygen concentrations, such as LOX. Therefore, Humphries maintains that firefighters would not want to wash away LOX not knowing what, if any of these materials are present in the environment. It is best just to leave the material where it is and leave it alone, it will eventually dissipate.

In the event LOX is spilled over asphalt or other surfaces contaminated with combustibles such as oil-soaked concrete or gravel, or comes into contact with any hydrocarbon such as oil, grease, alcohol, coal dust or gasoline, it could burn with nearly explosive violence if ignited. Such a source of ignition may be an impact or shock, heat or static discharge. In effect, then, the product becomes what Suedekamp, who commanded the hazardous materials sector for this incident, refers to as a "contact explosive" when it is spilled onto pavement.

The Compressed Gas Association recommends if there is a spill of LOX on the pavement, not to walk on or roll equipment over the area for at least 30 minutes after frost from the LOX has disappeared.

To the emergency responder's benefit, trailers used to transport liquefied oxygen are built to Compressed Gas Association Specification 341. They are equipped with three safety features:

1. A manual vent valve that communicates directly with the pressure side of the trailer. Its purpose is to vent the internal tank pressure. This was the valve opened by the Oxford firefighters when they arrived on scene. The manual vent valve is opened to relieve the pressure down to the desired pressure. Then the valve is closed.
2. The main safety valve is an automatic self-closing valve that is set to relieve itself when the internal tank pressure reaches 38 psi and will re-seat itself once the pressure is less than 38 psi.
3. A bursting disc that is set to open up at approximately 57 psi. Once the bursting disc ruptures at the designed pressure, the product will continue to vent until all of the liquid oxygen is released and vaporized, thereby protecting the inner tank from internal pressure damage. This valve does not re-seat itself.

In addition, Humphries said Cryogenic trailers are equipped with one more safety device called a fire valve or block valve. The valve can be tripped manually in the event of a fire. It is also connected to a spring-loaded fusible link system that will melt in the event of a fire and allow the valve to close on its own, stopping any flow of liquid from the inner tank to any external piping.

Humphries maintains that because of the safety features built into the trailers, and contrary to what Hora was told at the incident scene, pressure of the liquid oxygen inside the tank was not an issue because of the safety system regardless of the position of the trailer. Had firefighters not vented the trailer manually, the bursting disc would have ruptured eventually and vented the trailer as designed. There was no danger associated with pressure in this accident. As it was, pressure in the tank never rose above 38 psi because firefighters opened the manual vent valve. The tankers normally travel with the product at 28 psi.

Hora said there was some concern about the integrity of the tank because of the damage it sustained in the accident and also whether any of the safety features such as the bursting disc had been damaged.

Humphries also said, to calm fears of a trailer carrying LOX exploding or starting on fire, that because of safety systems on a liquefied oxygen trailer, it could not erupt in a fireball. In addition, erupting in a fireball is not a property of oxygen - even in it's concentrated refrigerated liquid state. Oxygen itself will not burn; it is a non-flammable, but it readily supports combustion.

Going back to basic firefighting 101, two other elements need to be present for fire to occur: a combustible material and an ignition source. Hence, the oxygen would have to come into contact with both before a fire would occur. Anything LOX may come into contact with outside the trailer would, though, undoubtedly burn with more vigor, and as in the case already mentioned of asphalt and other products with explosive intensity. Consequently, the utmost of caution in dealing with the hazard is still advised.

Hora observed that at this incident there was in addition to the blacktop hazard, spilled diesel fuel from the wreck and also the hazards of potential spilled oil and oil on the truck tires. He also believes that static electricity in the firefighters protective clothing may have been enough to provide an ignition source in the right situation.

Looking back on the incident, Hora recounts one lesson learned and something he would have done differently. That was to establish a safe zone earlier and farther back from the accident. LOX has numerous medical and industrial applications. Trucks towing tankers full of the product routinely pass through many communities. Any emergency response agency could be faced with the same situation faced by emergency responders to the Oxford incident.

Like any of the many hazards a small rural fire department may face, education and awareness are the key to keeping yourself on the safe side of misfortune.