Most high pressure bags are made from reinforced Kevlar with some manufacturing variables. The majority of these bags are square or rectangular, but there are round versions on the market as well.
People also tend to let their guards down when driving in nice weather, and with the continued abuse of texting while driving, wrecks will continue to increase.
The past several articles we have been looking at airbags and how they actually work. We discussed the physics behind them and looked at the different types we have at our disposal. Every type of bag has its own characteristics and capabilities and should be chosen for the particular job at hand. This article we will look at high-pressure bags and how to safely implement the use of airbags. We need to also remember that the higher we lift with a high pressure bag, the less it will be able to lift. When lifting with low pressure bags, the lifting force will remain constant. The drawback is they are not as stable for a lot of the lifts that we would do. They need to be used on good, flat surfaces and where the flexibility of the bag while inflating is not an issue. High pressure bags will lift a lot more weight and are much stronger and durable during the lifting process.
Most high pressure bags are made from reinforced Kevlar with some manufacturing variables. The majority of these bags are square or rectangular, but there are round versions on the market as well. They have an inlet valve on the corner of the bag where the inflator hose connects. They all have some type of shut off valve as well. These shutoffs will allow you to inflate the bag and then shut it off and remove the inflator hose. This might be practical if you are going to be on the scene for a period of time, and need to get the hoses out of the way for safety reasons. Pillow bags come in a range of sizes, from a small one-ton bag up to a 70-ton bag. Most of the time two or three bags are all that is needed, and the sizes you choose will vary on what you do. Sometimes a small bag can get you started up enough to be able to place one of the larger bags. They have inlet pressures that vary from 90 psi to 147 psi.
Let’s take a look at the procedure of safely using airbags for lifting. This especially is important when you are involved with heavy vehicle rescue and are having to lift larger loads. You airbags should be inspected on a regular basis for cracks, irregularities and to make sure the inlet fittings are good. Pillow bags have a life span of around seven to 10 years. I have seen cases where the inlets fitting blew out and the bags had a ballooned area upon inflation. Not something you want to have or see on a rescue scene. Next is the placement of the bags for your lift. Even though airbags are pretty rugged, they can be damaged by high heat and sharp edges. Most bags are more susceptible to damage while being inflated as the fibers get tighter as the bag expands, making it stronger on full inflation. Make sure the lifting spot is clear of sharp edges that could impinge on the bag during your lift. Also make sure that the bag is clear of all the exhaust system.
You want to place the bag where you can get the most out of your lift and accomplish the task at hand. The higher you lift the more unstable the bags may become. You can use two pillow bags stacked to gain a higher lift, but be extremely careful because as the two bags become inflated the surfaces will begin to round out and the bags can become unstable during the lift. You may not want to go to the maximum capacity of either bag when stacking pillow bags.
Pillow Bag Lift
The round air bags are more stable on a stacking situation because the surfaces do not round out. Your lift will be less likely to shift, or the bags become unstable. This is a much better option. Your other option with pillow bags is to use only one bag, crib, and then re-set the bag for another lift. This will eliminate the hazard of stacking. Next, look at where the rescuers need to be when the lift is being conducted. Airbags have injured and killed firefighters, so the location we handle the lift from is quite important.
Another consideration is when placing your airbags; pick a location that has a somewhat flat surface if using pillow style bags. These bags have a tendency to wrap around an axle or narrow piece of metal. You can still lift some, but it will be greatly reduced as the bag will expand around the object and you will lose a large portion of the raise. To compensate for this, run a row of 4”x4” cribbing across the top to maintain a better surface area. As the bags rises, the surface area will still diminish and the end cribs may even dislodge. This is a disadvantage to pillow style bags we have had to overcome for years. The round bags do not have this issue, a plus for those types of bags.
Once the bag(s) are in place, a “V” should be established in front of the bags. This will be considered the kick out or danger zone. Should the airbags kick out, then no one will be in the path. The person controlling the lift should be off to the side and concentrating on the gauges and lift pressure more than watching the vehicles being lifted. Another rescuer should be calling the lift while watching the vehicle go up. This rescuer will be commanding the controller as to the speed of the lift, air in or air out. They will also be commanding the cribbing operation which should be done as the vehicle goes up. My theory is that the cribbing should remain in contact with the object being lifted at all times. This is done using wedges to follow the lift and not placing cribbing every so often as the raise is being done. Something I have seen time and time again. Struts are also a great option for following your lift on heavy vehicles.
Remember that airbags are a lifting device, not a stabilization device. Should the air escape from the bag, the load will come back down if there is nothing else in place to hold it. Don’t take any chances when trying to lift heavy vehicles, it is not worth it. Take a little extra time to perform a safe and successful lift. We have looked at airbags and struts as two good options for lifting. In a lot of heavy vehicle crashes, our concern is to lift the heavier vehicle off the smaller vehicle in order to extricate our victims. Heavy vehicle wrecks can be a lot more hazardous because of the weights and gravity we have to deal with. Be sure and work safe and smart around these situations.
When you can take a heavy vehicle class, take it. Most departments don’t get the opportunity to train with large vehicles, so it is well worth the time and effort. Until next time, train hard, stay sharp, and play safe.