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In Carrollton, TX, the fire department was conducting a simple company-level “skill drill” with its airbags. During the lift of an SUV, the bottom bag in a two-bag stack suddenly failed. The blowout ruptured through the outer rubber layer of the airbag, causing the collapse of the bag itself. The cribbing, properly placed for the lift, safely took the load.
In Massachusetts, students attending a basic vehicle rescue class were using cribbing and a high-pressure lifting airbag to lift one side of an older automobile. The 20-by-24-inch, 26-ton-rated airbag was manufactured in 1985. With two box cribs in place, one on either side of the lifting airbag, the lift began. The airbag catastrophically failed at a working pressure of approximately 80 psi reading on the line gauge. Analysis afterward showed that the airbag had ruptured from the inside out, resulting in a slit approximately 10 inches in length near an edge of the bag. Due to proper cribbing placement, when the vehicle suddenly dropped, it rested on the cribbing. In both the Texas and the Massachusetts incident there were no injuries. This is due to the fact that in both training exercises, proper lift and cribbing procedures were followed.
Vetter recommends that the bags should be hydrostatically tested at age five years, seven years, nine years and then every year after. A hydrostatic test means that the airbag is filled and pressurized with water. A department can consult with the manufacturer of its brand of airbag equipment for full details on the feasibility of having service-life tests conducted for the units. For a department wanting to conduct its own life-expectancy test on its airbags, each bag must be placed outdoors on a level surface. You must create a system whereby you can completely fill the airbag with water and pressurize it with water at a pressure of 1.3 times the maximum working pressure of the airbag for three to five minutes. For example, an airbag that operates normally at 118 psi air pressure must be pressurized with water to a pressure of 153 psi (118 multiplied by 1.3). If the bag holds its water, it passes. If it fails, the bag blows out and self-destructs.
While there is no guarantee how long an airbag will perform during its years of service, having the water-pressure test conducted on your airbags increases the chance for successful performance.
Be aware that it is possible – even though unlikely– that a high-pressure lifting airbag could burst during the water test. For this reason, this test should be conducted in the open air, not indoors, at a safe distance from people, objects and buildings. Also, the operator should wear personal protective equipment.
Ron Moore, a Firehouse® contributing editor, is a battalion chief and the training officer for the McKinney, TX, Fire Department. He also authors a monthly online article in the Firehouse.com “MembersZone” and serves as the Forum Moderator for the extrication section of the Firehouse.com website. Moore can be contacted directly at Rmoore@firehouse.com.