Heavy Lifting with Airbags
By David Pease, The Reds Team
Last issue we looked at how airbags work and the physics behind how they do the lifting that they do. Many do not understand how the lifting process works and how the true capability of airbags is calculated.
Not realizing that the lifting diminishes quite a bit once the bags get over several inches high can cause even the best laid out plan to not work, as you wanted. I am not going to go back over the formulas, but if needed, go back and review the article from the last issue. Knowing ahead of time the true lifting power of your airbags will go a long way in your extrication plan.
Airbags come in a variety of sizes and load capacities. They also come in three different air inlet configurations. You can choose from low-pressure bags, medium pressure bags and high-pressure bags. A lot of folks think medium pressure bags are actually low pressure and the difference in inlet pressure is really not much. Low-pressure bags operate at around five to eight PSI, where medium pressure bags operate at around 15 PSI. You can see the difference is quite small for these bags. Most of these bags have an average lift of around 15,000 pounds. As with any equipment we use in rescue, there are always give and take situations. So let’s look at those for a minute with the low-pressure bags.
One plus for these bags are they will lift much higher than the typical high-pressure bags, which can lift from two feet to heights of over 10 feet. Because of their high lift capacity, they are the choice of a lot of heavy towing and recovery companies. They are good for lifting large trucks and are also used in aircraft recovery work. I was in California some years back and had the opportunity to work on some very large commercial aircraft. I also got to see different techniques used for lifting and extrication. I watched them lift a 747 completely off the ground using low/medium pressure airbags. It was impressive.
The other plus is they maintain their lift capacity during the entire height of the bag. The reason is that the surface area does not decrease. They require only a small amount of pressure to make the lift. This makes the bags ideal for certain situations but not necessarily the best for what we do in the extrication world. The bags are relatively large so they are hard to place in most of the rescues we do. They also are extremely flexible during inflation so the surface area must be smooth and consistent. The bags will start out by expanding out as they inflate, so being close to other structures can create a major problem. These bags are also not as strong when it comes to the construction of the bag and are more prone to tears and punctures if not used and placed properly. Now, I am not saying they do not have a place in rescue, but technicians need to be well trained in their use before placing them in the field. I witnessed a department puncture a low pressure bag during a training exercise and then place another one they had in a situation that did not work. They had to remove that bag and go to a high-pressure bag.
As you can see in some of the photos, used properly, these bags can do great things for you. But they need to be used correctly. They can make a great addition to your cache of equipment, but having a choice of high versus low-pressure bags, high pressure should always win out as the first online choice.
Next issue we will look at the characteristics of high-pressure bags and how they are used, as well as the use of airbags for heavy vehicle lifting.
Even though you will not see this until after Christmas, I want to wish everyone a very Merry Christmas from my family to yours. Stay safe out there and spend time with family and friends. Our jobs in public safety keep us away from our homes and families too much; we owe them as much quality time as we can give them. With winter, also comes the bad weather, so use extra caution driving when the roads are bad. Train when you can to keep your skills at their best.
Comments & Ratings