HANDLING FLAMMABLE/COMBUSTIBLE LIQUIDS CARRIERS
BY GENE P. CARLSON
As the fire service moves into the 21st century, there is an increasing use of flammable (gasoline) and combustible (diesel, heating oil) fuels. With this comes the ever-increasing number of tank trucks carting these fuels across our interstates, highways, and streets.
The fire service will respond to incidents involving leaks, spills, and fires with these vehicles. Preparation for handling emergencies begins with training on the construction and safety features of these trucks, reviewing how these containers react during fire conditions, and developing tactics for fire extinguishment and spill control.
Most of the construction features are designed to enhance the safety of the vehicles. Features include the following:
reinforced aluminum (meltaway) tanks;
steel (more accident-resistant) tanks, but no longer in common use;
elliptical shapes for roadability;
baffles and bulkheads;
protected placement of loading/unloading stations;
internally placed safety (fire) valves;
emergency valve shutoff controls;
fusible links or nuts;
breakaway piping;
pressure-relief devices and fusible plugs;
vapor-recovery system;
rollover protection;
undercarriage protection; and
rear-end protection.
Firefighters must be trained in how to recognize and use these devices to their advantage during emergencies.
Newer tanks manufactured from aluminum will puncture easily in an accident but have the advantage that under fire conditions the skin will melt, releasing any pressure buildup long before the tank ruptures explosively (BLEVE). Steel tanks, although more puncture-resistant during an accident, can violently rupture when the vapor space is exposed to flame impingement. Steel tank shells must be kept cool with large-capacity solid-stream nozzles to avoid overpressure. Aluminum shells must be kept cool to keep fire from spreading to adjacent compartments and involving additional fuel. When possible, burning fuel should be flushed from around and/or under the tank.
PRACTICAL APPROACHES TO TANK-TRUCK
INCIDENTS
There are four tactical approaches to tank- truck incidents.
1. Assemble the resources and extinguish the fire with Class B foam. Be sure an adequate foam supply is available before initiating the attack. Blended alcohol fuels will require a polar solvent/alcohol-type foam concentrate.
2. For combustible liquids, extinguish the fire with water fog when this can be done without creating environmental problems with the runoff. Large, hot fires of combustible liquids (such as tank trucks) will require foam application for timely extinguishment.
3. Protect adjacent exposures, and allow the fuel to burn itself out. If the incident occurs in a rural area, obtaining sufficient water for items 1 or 2 above can be a problem. Develop plans for sustaining water supplies with fire department vehicles or large-diameter hose relays along major roads and expressways.
4. Unignited leaks and spills should be diked immediately at a safe location and the liquid covered with foam to suppress and control the flammable vapors. Remove all ignition sources.
Before or during response. Units should obtain initial information concerning weather conditions, especially wind direction and speed, and, if available, the name of the product involved in the incident. Find out if the product is still leaking, pooled in a spill, or burning. Are there fumes or vapors adjacent to the site? What is the location of the product and/or vapors?
Are they on the road, in a ditch, or in the sewers?
Are they blocking access of emergency vehicles?
Are they blocking access to people or property?
While en route. Plan your approach only from the upwind direction. Review the product (if known) in your reference materials, including the following factors:
exposure symptoms,
reactions with extinguishing or diking agents,
health effects, and
initial actions recommended.
On arrival. Use the following guidelines/procedures:
Stay away from wet areas or spills. Position apparatus uphill from leaks, spills, and vapors.
If vapors are suspected, maintain a safe distance–the invisible cloud is usually much larger than the visible cloud.
If no release is detected, look for people who are ill or unconscious. If people are down, maintain a safe distance until you know the situation and product(s) and can adequately protect your firefighters.
Get information from people on the scene (driver, plant official, eyewitnesses, and any shipping or other identifying papers).
From a distance (500 feet), use binoculars to look for placards or other warnings and the product name or number on the tractor or trailer.
Stay back and check out the situation slowly and carefully before doing anything. Identify the product!
Initiate an incident management system with a command post and staging area on the upwind, upgrade side at a safe distance.
Establish site control with entrance/exit points for the emergency responders.
Get technical assistance (ChemtRec® or Canutec).
Always go in slowly to avoid getting into trouble before you realize it. Perform an approach size-up from a safe, secure position.
You may have to step well back from the incident and send in a fully protected reconnaissance team to check the situation. The team should go in slowly and use combustible gas indicators and explosionproof lights and radios–and stay out of observed spills.
Establish an isolated holding area for personnel or victims who become contaminated.
Remember that you do not carry the equipment and chemical protective suits for all types of hazards.
Some flammable/combustible liquids and vapors are toxic and can be absorbed through the skin and standard protective clothing and have no odor.
If you cannot find out which product is involved, treat it as a highly toxic, violently reactive, or explosive substance.
Initial actions include rescuing occupants of vehicles (body recovery can wait) and protecting exposures. Remember that the tractor or uninvolved portion of a multiunit is an important exposure. It may be necessary to disconnect the tractor or unhitch a trailer and remove it from exposure. Diking around the vehicle or damming a drainage ditch may be required to limit a running-spill fire.
Attack from high ground with the wind at your back, checking for any overhead wires and coordinating streams so they do not oppose each other. Flush the fire away from exposures and into less hazardous areas. If agent is limited, use it to protect exposures. Agent that runs off is wasted. Do not wash away foam blankets with water streams.
Vehicles that are rolled over and not involved in fire must be unloaded. Of the various ways to do this, drilling aluminum tanks and pumping the product out is the most successful. Make sure the tank is bonded and grounded before using an air-operated drill. Continuously monitor for leaks and flammable vapors. Foam immediately on vapor detection (refoam every 20 minutes if resources are available). Do not expend your entire foam supply; adequate foam must be available in case of ignition. Have foam hoselines in place, and provide a nonskid surface for the firefighter doing the drilling. Protect storm and sanitary sewer openings and drainage ditches in case of a spill.
As shipping increases in your locale, train your firefighters and fire officers in handling tank vehicle emergencies. Know where to obtain the technical assistance and resources to bring these incidents to a quick, safe conclusion for the protection of your community.
GENE P. CARLSON, a fire education and training specialist, is director of international marketing of Oklahoma State University`s Fire Protection Publications, representing IFSTA nationally and internationally. Carlson is a member of various committees of the National Fire Protection Association and the International Association of Fire Chiefs. He served on the staff of the National Fire Academy, the University of Maryland Fire and Rescue Institute, and the University of Illinois Firemanship Training Program.
