Considerations for High Pressure Air Bag Use
Kevin Sears
The rising threat of terrorist related building collapse has lead to an increased demand for high-pressure air bags over the past few years. Their ability to rapidly deploy and extricate victims effectively is unparallel in a vast array of situations.
Unfortunately, like several other tools carried on our apparatus, a lack of regular use of the air bags often weakens the operators’ comfort level and knowledge of the equipment. When deployed by untrained rescuers, the dynamic tool could inflict unnecessary harm to both the victim and the operator.
A good review of “Air Bags 101” is beneficial to every member of a rescue organization. Next shift, bring the company out to the bay floor to cover basic tactical considerations when using your high-pressure air bags. You’ll be amazed how little has been retained since their original “Air Bags 101” class at the academy.
Size Up
In order to effectively initiate an air bags operation, start by taking two steps back from the incident and evaluate the entire picture:
What needs to be lifted?
How much does the object weigh? (Remember: Air bags are usually rated in Metric Tons…1 Metric Ton = 2200Lbs.)
What is the distance between a stable base and the object to be lifted?
Where is the center of gravity of the object being lifted?
Is there enough stabilization equipment to support the object as it is being lifted? (Cribbing, shoring, ect.)
Can this incident be handled with the air bags on the rig or do I need additional help?
Air Bag Lifting Ability
A problem with some air bags is that the lifting capacity originally printed on the surface is often worn off, faded or otherwise damaged. A quick streetwise trick to figuring capacity of a non-labeled bag is:
Multiply the length and width of the bag (For example: 20” x 20”) Take that number and multiply it by the operating pressure (118psi) of the bag. The number obtained by multiplying the two factors is the amount of weight (in pounds) the bag can effectively lift.
For example: Bag dimensions are 20” x 20” = 400 square inches
118psi x 400 square inches = 47,200lbs or 22 Tons.
Calculate the lifting capacity of the air bags carried on your apparatus. If worn off, repaint the number on the surface to facilitate a more expedient operation when called to your next pin-in.
Always be sure to choose a bag that will undoubtedly lift the object. Having to shut down an operation to switch to a stronger air bag will drastically slow operations and potentially cause surrounding objects to become unstable.
Placement Considerations of the Air Bag
During your size up, you have determined the distance between a stable base (usually the ground) and the object to be lifted. A disadvantage of high-pressure air bags is their low inflation height. Remember that when the bag nears its full inflation, the rated capacity declines because surface contact area decreases. To overcome this set back, we need to bring the bag closer to the object being lifted.
Stacking the high-pressure bags is one way to overcome the problem of decreased surface contact. This should only be done on a stable base with the largest bag on the bottom of the stack. When performing a stacking operation, remember, the maximum lifting capacity is limited by the smaller bags capacity.
For example: If you stack a 22 Ton bag on top of a 70 Ton bag, the maximum lifting capacity is only 22 tons!
When operating a stacked set up, partially inflate the bottom bag first. This increases stability by allowing the top bag to cradle the bottom one when being inflated.
Erecting a cribbing tower is another way of bringing the bag closer to the surface of the object being lifted. Use caution when building such a support device. The height of the tower should never exceed twice the width of its base. Also, some type of ground pad or solid crib must be placed under the tower to distribute the weight it takes on. It is good to keep in mind that using traditional 4” x 4” timber box cribbing is rated for approximately 12 tons, whereas using 6” x 6” dimensional timbers increases the strength to 30 tons.
High-pressure air bags have proven their value in emergency situations throughout the world. Although originally used for vehicular and machine extrication, modern times have dictated a new wave of their operation. The reality of more terrorist attacks on our land is undeniable. The structural collapse potential associated with these incidents could trap not only civilians, but our brother firefighters as well. On going training on this equipment must be implemented. You never know who will be on the underside of the rubble.
FEATURED DRILL
High Pressure Air Bag Operations
Required Equipment:
1 Rolling garbage dumpster
1 Rescue manikin or simulated victim
1 Raw egg
1 Complete High Pressure Air Bag kit
Sufficient cribbing
Objective:
Remove victim trapped under simulated “rubble.”
Place simulated victim under the garbage dumpster using pry bar or manual labor. Place the raw egg on topside lid of the dumpster. Have crews evaluate incident and determine what air bag capacities will be needed (instructor determines the simulated weight). Lift the dumpster off of the victim while stabilizing the object with proper cribbing techniques. Operate the air bags without causing the egg to drop from the lid of the dumpster. Remove the victim once the dumpster has been lifted high enough and properly cribbed, ensuring the safety of the rescuers.
This is an effective drill that teaches smooth control techniques. The egg adds a fun twist. A huge advantage is that if the dumpster has wheels; it can be rolled into the apparatus bay if weather doesn’t permit outside activities.
