Troubleshooting
Lift Bag Troubleshooting
Construction
The most likely area for this system to leak is in the textile bag. Not considered “consumable” but also not impervious to wear and tear, the bag has been constructed using 1000 Denier Cordura as an overbag… The same thickness and ruggedness of a parachute bag. The working pressure in the bag is maxed out at 4# at which point the relief valves will open. This is exceedingly small as it relates to o-rings, many of which are rated for thousands of pounds of pressure. The zipper is rated for over 17 psi, and the seams for more than double that. This bag should take most reasonable chafing and handling abuse, and a tear in it is not going to hurt the inner bag.
The internal air bladder is made of a nylon reinforced PVC pack cloth… both water and air impermeable, but with the strength characteristics of a serious outer material itself. All seams are heat welded and sealed, and all stitching is taped and double or triple stitched.
Depending on use, it is most likely that the lift bag is damaged while being dragged over the beach, or over a barge in a Raise Tow Beach/Barge mission profile. In each case, the system has completed the lifting job, and the shape has been recovered so repair is administrative. Most tears during this phase are pretty obvious, and often are catastrophic, requiring a new bag to be fitted.
In the event that the injury to the bag is small enough, we have included a patch kit, stored in the Field Repair Kit that should allow for emergent contingency repair. Step one is to find the leak. A large leak will be obvious enough, so we will focus on a small leak.
Inspecting the bag
If the lift bag doesn’t pass the test inflation, deflating slightly over the period of the test, you will obviously have a small leak. It does not take much of a leak to really decrease pressure immensely. The best way to find the leak from this point is to get a simple spray bottle and make a solution of dish soap and water. The soapy water solution will bubble dramatically when sprayed over a leaking area. With the bottle inflated as much as possible (relief valves lifting) spray down the fittings passing through the bag. Then spray down the bolts in the baseplate, including those holding the clamp ring on, the clamp ring to bag surface, the Inflation Valve Assembly, the machined lift eye and the pneumatic line bulkhead fittings. If none of those are leaking, start spraying down the entire bag, starting with the seams, and looking for less dramatic bubbles from the Cordura overbag. The Cordura won’t hold air itself, but it also won’t necessarily pinpoint a leak, it will diffuse it around a region.
Once the leaking area has been found, proceed to the relevant section in the following pages.
Relief or EIDV Valve Leakage
The relief valves, External Inflation/Deflation Valve assembly are the most likely suspects. Both of these valves are spring loaded, and have a soft sealing surface that can be fouled with some contaminant or corrosion.
First step is to rinse the valve with fresh water while actuating it manually. Disassembly it may be unnecessary, and can allow a gasket surface leak after that, so the first attempt should be made at doing this rinse with the valves still installed.
Relief Valves: These high quality Leafield Marine valves are easily accessed from the front and the rear. In front, pry the debris screen off using a soft tool or your thumb and check for sand or debris behind the screen. Thoroughly hose and blow off the front of the valve while reaching in and actuating the valve with a finger. Hold it open while rinsing, and then blow the valve dry with compressed air. Then reinflate and check for leaks. If that solved the problem, clean and replace the debris screen and carry on. If the leak persists… replace the valve.
External Inflation Deflation Valve (EIDV): The most likely culprit, the EIDV is easily accessed from the front by unscrewing the cap and simply hosing it out. The valve has a large sealing surface, but also has an o-ringed cap that should prevent the valve from losing air, even if the spring valve is leaking. A failure here means two failed sealing surfaces, which likely means time for a replacement.
Relief Valve Actuation
Zipper Leakage
Brush clean zipper with soft brush
Seam Leakage
EIDV Valve Actuation
The waterproof zipper, similar (identical) in style to what is used on drysuits and dry bags, is an often overlooked maintenance item. The Field Repair Kit includes a zipper wax stick that is designed to lubricate and soften the rubber seal on the zipper.
Open the zipper and clean with a soft brush and some soapy, clean water . Try and make sure that the zipper is clear of debris and corrosion, particularly around the area of the observed leak. Make sure it doesn’t have any loose threads coming through it or anything else of that sort. Rub the entire zipper thoroughly with the zipper wax, and run the zipper up and down a few times until the action is nice and smooth. Re-test to ensure that the leak has ceased and put back into service.
If the leak persists, repeat the cleaning and wax application process and retest. If it is still leaking due to deformation or damage, the bag will need to be replaced. The zipper is heat-welded into place, and cannot be replaced easily or effectively.
Apply Zipper Wax to all surfaces
The most difficult to solve is a seam leak. The seams are all heat welded, taped and tested. If one has split or de-laminated it may be possible to re-glue it, but care must be taken to prepare the surface properly.
Clean the mating surface with Isopropyl Alcohol and apply the Aqua-Seal glue to both sides, all the way to the edges and slightly beyond and let it dry for a few minutes, skinning over.
Once it has skinned (kicked off), press the two surfaces together and apply pressure using weight or spring clamp. Wait an hour and proceed.
Next, cut a strip of the repair fabric 1” larger on all sides than the repair area. Repeat the gluing process, letting each side dry slightly before joining the surfaces and applying pressure.
Wait 24 hours and retest.
Bolt Leakage
Unlikely, but easy to repair is a bolt leak. Quite a few of the bolts pass all the way through the system and can allow the threads to pass an air leak. If a bolt is leaking, simply remove the bolt, clean the threads and the threaded hole and apply Aqua-Seal adhesive to the bolt. Wait a couple of minutes for the adhesive to start to kick and reinstall. Wait for 24 hours and re-test.