Thursday, November 20, 2008
Pry, Pry Again
As today's vehicles become safer for their occupants, little is being done to protect our first responders. With as many as 12 airbags in one vehicle and voltages as high as 500 volts, updated extrication training is a must.
There is a risk of injury when working around any airbag, deployed or undeployed. Maintain safe distance at all times. Practice the 5-10-20 rule: 5 inches from any side airbag, 10 inches from the driver's frontal airbag and 20 inches away from any passenger frontal airbag. Today's vehicles may be equipped with the following airbags:
Frontal driver and passenger airbags. The driver's frontal airbag is located in the center of the steering wheel. The passenger frontal airbag is located either above or in place of the glove compartment. One or both frontal airbags may be equipped with dual inflators, which means that the same airbag can deploy a second time.
Dual-inflator airbags are designed to deploy on the first stage only, first stage and then second stage after a short time delay, or both stages at the same time depending on the severity of the collision, seatbelt use, seat position and occupant weight. If only the first ignition stage of a two-stage airbag has deployed, this can't be seen from the outside. Despite a deployed airbag, the same safety precautions must be followed as if the airbag had not deployed.
If the passenger airbag has not deployed, placing weight in the seat may send a signal to the control module that the seat is occupied and deploy the airbag.
Side airbags or head/thorax airbags can be located in only the driver seat, both front seats, or front and rear seats. They also may be located in the front doors or both front and rear doors. These airbags are triggered whenever a high vehicle deceleration or acceleration rate in a side direction is sensed during the early stages of a collision. These airbags are designed to deploy independently from the frontal airbags. They also may deploy if the vehicle senses a rollover situation. Triggering of these airbags may depend on the size and seating position along with the weight of the occupants.
Side curtain and tubular side airbags are designed to deploy when the vehicle leans at an angle of approximately 52° or the vehicle senses an excessive lateral force for an extended period of time. These airbags may be located in the doors of convertible vehicles, entire side roof area of the vehicle or just the front-seat roof area of the vehicle. All side curtain airbags are activated by a compressed-gas cylinder containing approximately 3,000psi of pressure.
The compressed-gas cartridges for the side and curtain airbags must not be cut. The bursting of the gas cylinder may lead to sharp-edged parts being ejected at high speeds. The load noise may result in blast trauma.
Knee airbags are located below the steering column on the driver's side or also below the glove box area on the passenger side of the vehicle. Knee airbags are designed to increase protection for the drivers and passengers knees and help position the front seat occupants in the maximum safety position for the frontal airbag deployment. Deployment of these airbags is dependent on the use of the seatbelt and deployment of the frontal airbags. When inflated the knee airbags will push the lower trim panel forward to contact the knees or burst through the lower trim and inflate.
Other restraints
Today's vehicles may be equipped with the following restraints:
Deployable roll bars. Many convertible vehicles are being equipped with one of three types of roll bar protection. The rollover protection is designed to protect the occupants against severe injury in a rollover situation. The roll bar is also designed to give the occupants a survival space when the vehicle is upside down. The rigid roll bars are located on the driver and passenger sides of the vehicle behind the front seats. These bars are made of tubular steel or structural aluminum and are bolted rigidly to the vehicle structure. The dual extendable roll bars also are located directly behind the front seats and may be concealed by a piece of trim or may be part of the headrest. These roll bars are activated by a compressed spring and are locked into place to prevent them from collapsing when deployed. The single retractable roll bar is operated hydraulically and extends across the entire width of the vehicle interior behind the seats. It also activates when a rollover situation in detected, but can be raised and lowered manually with a switch on the dash or center console.
Seatbelt tensioners may be located in the B or C pillar, under the front seat lower cushion, or in the front seat back cushion. The tensioner deploys a fuel cartridge that drives a piston that in turn pulls a steel cable, causing 4 to 6 inches to be removed from the seatbelt webbing or buckle assembly. Deployment of the seatbelt tensioner may be dependent on the seatbelt being buckled.
Pre-accident sensing is designed to position the occupants in the best possible position before the collision so that the airbags and seatbelts can provide the maximum protection in the crash. This is accomplished by automatically tensioning the seatbelts with a high-speed electric motor, moving all occupied seats to the maximum safety position, and closing the sunroof to provide the maximum upper-body structural support. If no crash occurs, seats, seatbelts and sunroof return to their normal position.
Initial steps
The following procedures should be followed when working with airbag-equipped vehicles.
Secure the scene. On arrival, ensure that all equipment is positioned so personnel are safe and the scene is secure.
Size-up and assess the scene from all angles. Take care to note any hazards or additional damage away from the initial approach. The first priority is to assess the condition of all patients. Be aware that patients may have been ejected from the vehicle.
Establish a chain of command that includes a safety officer.
Stabilize the vehicle. Trapped victims are in direct contact with the vehicle structure, so the substructure must be blocked and supported so there's no movement during rescue operations. Unintended movements may cause further injury.
The vehicle must remain secured during the entire rescue operation. All air must be removed from the tires by cutting the valve stems or puncturing the sidewalls. The vehicle must also be secure enough to withstand the force of hydraulic tools.
Initiate a complete scan for airbags. Be aware that not all airbags may be identified by markings and that some markings will be concealed by vehicle parts, patients or debris in the vehicle.
Initiate a complete electrical shut-down. This will require access to the under-hood area, trunk area, interior of the vehicle, underside of the vehicle or under fender area of the vehicle. Be aware that many vehicles have two batteries. Both batteries must be accessed and shut-down. Also look for the presence of any added accessories on the vehicle such as hands-free cell phones and stereos. Any additional device that contains an alternative power source such as a battery or capacitor may cause the system to remain charged. When disconnecting batteries or cutting battery cables, always cut the negative ground cable first to prevent short-circuiting and arcing.
Check for any fluid leaks or spills. Contain all spills and ensure that leaks are identified. Prevent sparks or heat sources from igniting any flammables. If leaks or spills are detected ensure that non-sparking markers are used.
Open the trunk to ensure that there are no hazards such as chemicals or explosives.
Initial openings
Once the vehicle is secure, extrication procedures can commence.
The initial patient-access opening will require opening the door or removing glass. Removal of glass may be required if access can't be made by conventional means, but try before you pry. Always lift the handle to gain access before cutting or spreading the door.
Always remove the glass when working on adjacent panels. Windows may shatter, resulting in tiny sharp pieces of glass flying around, which may cause injury to occupants or rescuers. Make sure that all glass breakage is directed away from the patient. The patient also should be covered to prevent glass splinters from entering eyes or wounds. Make sure that the inside medic or rescuer is wearing the proper protective equipment and that it remains in place during the entire rescue.
If the door can be opened with the handle, you may be able to insert the spreader in the resulting gap. If the door can't be opened, then a hinge attack or latch attack may be used.
Hinge attack. The hinge attack should be used whenever there's a door-mounted airbag. This will ensure that the rescuer's body is never directly next to the undeployed airbag and that there's no chance of the door flying open in the event of an accidental deployment of the door airbag.
Start by squeezing the middle of the fender to open a gap between the door and fender and expose the hinges. If the vehicle is equipped with a plastic fender, remove the glass and spread between the roof and the top of the door to create a gap. Place the tip of the spreader in the gap and spread the fender off of the body of the vehicle. This will expose the upper structural support of the vehicle, where a relief cut will be required for dash displacement, if necessary.
Cut the hinges or spread the door away from the A post. Hinge design will dictate the appropriate method. For example, it's easier to spread solid-steel hinges until the pin breaks than it is to cut through a steel hinge itself.
Latch attack. Try the handle first. If the door is locked or won't open, place a racquet ball or tennis ball under the handle to keep it lifted in the open position. This trick often will allow the door to open when only moderate pressure is applied.
Spread down and away from the patient by placing the tips of the spreader between the roof and top of the door. This will create a purchase point for the tips of the spreader at the rear of the door. The spreader also can be used to crush the center of the door and roll in the edges of the door to make a gap. This method can be used only if there isn't a door-mounted airbag.
Third-door conversion. This technique is used on two-door vehicles where access to patients in the rear seat is required. A relief cut is made at the base of the B post, and another relief cut is made as far back in the window opening as possible, straight down. The top of the B post is cut completely through, and the side of the vehicle behind the door is spread down and back to create a “third door” that allows access to the rear seat. Squeezing the center of the area below the window with the spreader will cause this area to crease and make it easier to fold down and back. The spreader also will act as a handle for the rescuer to pull.
Fifth-door conversion. Used on four-door vehicles when both side doors and the B post need to be removed, this procedure can be performed from front to rear or rear to front depending on the location and extent of damage and on which door can be opened.
Start by gaining access to the front or rear door by cutting the front door hinges or forcing open the rear door. Make a relief cut at the base of the B post, leaving the top of the post attached to prevent the post from folding in on the patient.Insert the tips of the spreader between the base of the B post and the door and begin spreading the post up and away from the vehicle.
Once the base has been spread away from the vehicle, make a cut through the top of the B post. A pie-shaped cut above the B post may be required due to the strength and multiple layers of steel in that location. Roll the entire side of the vehicle forward on the front door hinges or rearward on the rear door Nader pin.
Other access points
To gain access under the hood, pry the hood up halfway between the front of the hood and the cowl. This will expose the rear hinge and any gas struts. Cut the hinges at the rear and roll the hood forward. The hood can be cut off at the latch assembly or left in place. Many vehicles are being equipped with two latching points in the front of the vehicle, which makes access from the rear faster and more effective.
Partial or full roof replacement also may be required. If only a portion of the roof must be flapped forward or rearward, cut through the two A posts and make relief cuts on both sides of the roof. A spreader can be used to create a crease in the roof to act as a folding point. A pike pole or backboard on its edge also may be used to crease the roof.
If full roof removal is required, cut all four posts, making sure that the post closest to the patient is cut last. Walk the roof forward or rearward over the vehicle. Be sure to strip the trim to look for compressed-gas inflators. Cut above or below the gas cylinders, never through the cylinders.
The dash can be rolled forward or lifted to gain access under the dash. The decision to lift or roll will depend on the location of the strut tower. If the strut tower is attached directly to the firewall, then rolling the dash would be the best option. To roll the, dash make a relief cut through the upper support rail just forward of the strut tower. Make another cut in the lower corner under the door where the A post connects to the rocker panel. If the roof is still attached, make another cut through the A post as close to the roof as possible. This will prevent the A post from hanging on the roof. If the cut must be made lower on the A post, cut a pie-shaped piece out of the post. The door can be left attached to the A post. Place the ram between the upper door hinge and the base of the B post. As the post is pushed forward, the dash will roll upward.
If the strut tower is located forward of the firewall, then jacking the dash would be preferred. Make a relief cut between the firewall and strut tower. Cut the A post as close to the roof as possible, or make a pie-shaped cut to allow room for the post to clear the roof. Make two cuts in the A post between the upper and lower door hinges. Use the spreader to pinch the cut area and roll it forward. Place the spreader in the opening between the two hinges and spread the area upward from the side of the vehicle. This method will leave the entire side of the vehicle clear to work in.
Awareness is the key to safety. Knowing the hazards and how to work around them will ensure the safety of everyone. No two accident scenes are alike, but the goal should always be the same: Everybody gets home safe and sound. Only through training can our goal be achieved. Safety is no accident.
An expert with more than 30 years in the automotive field, Todd Hoffman has spent the last four years working closely with the fire service to develop advanced extrication procedures and accident scene safety programs. He is the founder of Scene of the Accident, a non-profit corporation dedicated to providing up-to-date safety training programs for emergency personnel at no charge.
Hybrid Vehicles Not Riskier
Hybrid vehicles pose no additional risks over conventional vehicles if handled properly. You can't be electrocuted by touching the vehicle. You can't be shocked or electrocuted by putting water on the vehicle or working on the vehicle when submerged in water. If the airbags have deployed, all high-voltage current is shut down. The following procedures should be followed when working with a hybrid vehicle.
Identify the vehicle as a hybrid
Hybrid logos are difficult to see and are often damaged or missing when involved in a collision. Look for orange cables under the car's hood.
Stabilize the vehicle
Chock the tires so that the drive wheels can't be rotated. If the accelerator pedal is depressed the vehicle will move forward or backward on electric power.
Remove the key from the ignition
The high-voltage current flow is shut down when the ignition is turned off. There is still high voltage in the high voltage battery and capacitors of the system. Be aware that some vehicles are being equipped with a “smart-key” that does not need to be inserted into the ignition. If the key can't be found there is a switch under the steering column on the dash that disables the keyless system.
Shut down the 12-volt system
Disconnect the battery cables or cut the battery cables, negative first and then positive to ensure that there is no sparking. The 12-volt system controls the flow of high-voltage current through the vehicle. When the 12-volt battery is disconnected, all high-voltage current is disrupted and normal extrication procedures can be performed.
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