Life Expectency of High Pressure Lifting Airbags

Does anyone have some documented recommendations on the life expectency of high pressure lifting airbags?

I'm looking for manufacturer recommendations as well as internal stuff.

Also, does your department have a pressure testing schedule in palce, etc? How often? Who does it?

Replies to This Discussion

Permalink Reply by Ben Waller on January 13, 2011 at 9:51pm

I've used them and I'm frankly not impressed.

One big negative they have is the steel center plates. I've seen that cause slippage in basic lift situations where the rubber-coated bags did not slip at all.

A slick metal plate lifting a slick metal car component (rocker panel, frame rail, etc.) isn't the best way I can think of to do it.

Just curious, do you sell the NTs or something?

Permalink Reply by Asst Chief Tim Cook on January 19, 2011 at 5:04pm

Nope. And I've used about every type of bag there is out there. For OUR operations the NT's are a good fit. In practice I've lifted a lot of stuff with NT's and NEVER had a problem with the plate slipping. If you really needed to, a truck flap would remove any potential problem there. Why do you think I have to SELL something to LIKE the product?

Permalink Reply by Asst Chief Tim Cook on January 19, 2011 at 5:08pm

Ben,please explain to me how you Hydro test ANYthing. I've watched the procedure many times and I have NEVER seen anything "Hydrotested" that WAS NOT restrained and WAS NOT tested in a enclosure under VERY precise conditions. Like Scba cylinders as an example.

Permalink Reply by Ben Waller on January 19, 2011 at 10:32pm

I don't hydrotest anything.

Hydrotesting a rigid cylinder like a compressed gas cylinder is a different proposition than hydrotesting an expandable, non-rigid air bag.

I'm just telling you about the one reference I could find to hydrotesting air bags.
How rigid cylinders are hydrotested isn't pertinent, because they aren't air bags.

Permalink Reply by Ben Waller on January 19, 2011 at 10:50pm

I looked again, and found the following:

Wilson Fire Equipment Hydro Testing procedure for Sava air bags - no reference to confining/restraining the bags.

Vetter's hydrostatic testing procedure specifies that the bag must be tested "free". That means the bag should not be "confined by a load or by other bracing".

And after an exhaustive search...ditditditdah, that's all, folks.

Permalink Reply by Asst Chief Tim Cook on January 21, 2011 at 8:30pm

Works for me. Thanks for the info Ben. Oh, I read the articles but outside of a leak,boil or crack how do you determine the safety of the bag?

Permalink Reply by Ben Waller on January 22, 2011 at 2:52pm

Visual inspections for obvious damage on a weekly basis plus interior visual inspections with a bore scope a couple of times per year and after any unusual use (near heat, corrosive chemicals, etc.)

Air bags typically fail in one of three ways:

1) A pinhole leak that deflates the bag if the air supply is shut off.
2) A leak or tear that develops during a lift.
3) A sudden failure from being used against a hot object or from a puncture during a lift.

The other failure method is a lateral failure during a lift, but that can't be overcome by testing individual bags prior to the call. That's completely an operational issue.

The first can usually be overcome by simply maintaining the air pressure, cribbing the vehicle/heavy object in place, and then taking the defective bag out of play. Even if the leak can't be overcome, the failure will be gradual and if cribbing is in use, the load will just settle back onto the top layer of cribbing.

The second and third failure types may cause a slightly faster failure, but cribbing already in place will catch the load.

I've done some pretty extensive research and cannot find a single confirmed report of an explosive rescue lift bag failure during an actual rescue lift. I also cannot find a single confirmed report of either a rescuer or victim being caused by a rescue lift bag failure during a rescue.

The issue isn't whether or not a bag can fail due to testing. The issue is the consequenses of a failure.

The other thing is that hydrotesting lift bags does will not prevent a subsequent bag failure during training or operations.

Permalink Reply by Ben Waller on January 22, 2011 at 2:53pm

I didn't say that you sell the product, I asked you if you did.

You didn't answer the question.

I've also used a wide variety of air bag types and the ones with the steel plates are easily the most problematic.

Permalink Reply by Ben Waller on January 22, 2011 at 2:56pm

If you need to cover the plate with a truck flap to prevent slippage, what's the point in having lift bags with the steel plate in the first place?

Truck flaps work just fine on the rubber-coat bags (Vetter, Paratech, Sava, Hurst, Holmatro, whatever), too.

Another issue is that the steel plates can potentially be a source of fire ignition if you have to do a lift around a fuel leak. That's not a problem with the rubber and brass bag types - they are inherently safe around fire hazards.

Permalink Reply by Asst Chief Tim Cook on January 30, 2011 at 5:26pm

Ya. I DID answer the question. NO, I don't sell the product. I respect your opinion but I suspect things in Hilton Head are considerably different than things here in Maine. INCLUDING traffic densities,vehicles and types of crashes. Now you and I can sit and argue about every little detail(and often do) OR we can accept we just don't always see eye to eye and in our given operational areas neither one of us is any better than the other.If you don't like Nt's that's fine. We DO,and they work well for the types of jobs we are asked to do.That's good as it keeps Mfgs EMPLOYED. If you're a Paratech guy,i've got no problem with that, we had them for years and we just like NT's better. it's just a preference. I doubt the guy under the vehicle CARES as long as we get them out SAFELY.

Permalink Reply by Asst Chief Tim Cook on January 30, 2011 at 5:30pm

Maybe so. How many of these events have YOU witnessed? In my 42 years here......ZERO! Same can be said for Rescue tools but I haven't seen a lot of problems here either. I DO NOT make a habit of covering the plate, I offered it as an OPTION if you really thought it was NECESSARY. We just agree to disagree.

Permalink Reply by Ben Waller on January 30, 2011 at 7:24pm

Where did you get the idea that my experience was limited to where I work now? I've worked/volunteered in several different states including working rescue in two high-volume urban systems prior to moving for my current employer. In a couple of those places, we literally worked dozens of extrications per year.

I also teach extrication in two different statewide programs and do a lot of extrication research, as well as participating in related rescue specialties like USAR where heavy lifting and advanced stabilization problems are the norm.

None of that has any bearing on the physics of a slick steel plate not necessarily being the best surface on which to rest another piece of steel for a lift, even if hte second piece of steel is in the shape of a car.

Lastly, I'm not a "Paratech" guy. I simply prefer systems that meet certain basic criteria, including being inherently safe and having lifting surfaces that are not inherently slick.