BC inflator flange repair

[snowdog61]

Aquaseal would be my 1st choice but pretty sure the factory installation would have been RF welding. I'd be pretty particular about making sure I wasn't grossly over weighted just in case things let go and keeping horizontal/head down if you get a bad leak.

 

[Zef]

Aquaseal would be my 1st choice but pretty sure the factory installation would have been RF welding.

I don't think it was RF welded as there is residue on the flat part of the flange that extends under the material.

-Z

 

[Zef]

So as I think this through...I am leaning towards just buying BP/wing to replace my BC...but if I can get a strong enough bond between fabric and flange I would have a backup BC....I am thinking a 2 part epoxy but not sure which to use....the area just inside the opening of the BC is a shiny/slippery surface and I am not sure what kind of plastic the flange is made from.

I need something that would bond the material and plastic together strongly and not become brittle when cured.

Any ideas?

-Z

 

[KeithG]

I don't think it was RF welded as there is residue on the flat part of the flange that extends under the material.

-Z

None of the flanges I have disassembled on several Sherwood BCDs had been welded in place.

The inside bladder nut has a pair of ridges that fit into a pair of grooves in the outside bladder nut. Along with a very little bit of adhesive, this forms an air tight seal by crimping the bladder material between the 2 nuts. The adhesive on the Sherwoods was not flexible as it did not extend past the bladder nuts. The adhesive was also present on the threads, so maybe it was mostly meant to keep the inner bladder nut secure?

 

[KeithG]

So as I think this through...I am leaning towards just buying BP/wing to replace my BC...but if I can get a strong enough bond between fabric and flange I would have a backup BC....I am thinking a 2 part epoxy but not sure which to use....the area just inside the opening of the BC is a shiny/slippery surface and I am not sure what kind of plastic the flange is made from.

I need something that would bond the material and plastic together strongly and not become brittle when cured.

Any ideas?

-Z

The strength of the seal comes from the clamping of the inner and outer flanges, not from the adhesive.

The bladder material does not stretch and hence does not "pull away" from the flange in any direction. All of the mechanical strength of the connection comes from the thread on the nuts. Once clamped tightly the bladder material will not move.

The adhesive is present to simply provide some gap filling measure to more easily ensure the seal created by the mechanical fastener is air tight. You are more interested in a gap filling adhesive, than an actual bonding agent that would form an air tight seal between the material and 1 side of the flange.

The above concept is also employed at the elbow connection. A rubber washer is compressed by the mechanical tightening of the elbow to form an air tight seal. For the flange the adhesive is acting like the rubber washer. It serves as a gap filling agent, not a strength agent.

Keep any adhesive within the circumference of the flange pieces - there is no flexing in the region, so no need to worry about flexing. Actually you really do not want any adhesive in a flex zone as that may create a future failure zone due to material movement affecting the adhesive bond.

Regardless, if you have access to industrial suppliers then something like Weldwood E6000 should be fine for a gap filling adhesive. My second choice would be Shoe Goo. Third choice aqua seal.

 

[Zef]

@giffenk , the concern I have is that this flange does not have an inner and outer nut....there is just the flange that was glued into the bc with the male threads protruding through the 2-inch hole, and then the elbow mated with the flange/seal and threaded "nut" of the elbow secured the elbow in place.

I may be wrong but You seem to be describing the inner and outer flange pieces that were suggested earlier, that screw together clamping the material, and then the elbow attaches with an additional piece that screws down to secure the elbow in place.

 

[Couv]

Zef, I would do my best to avoid using adhesive to make that seal. We already know that is a poor design or you would not be in this situation. Even if you have to make an internal vinyl patch (see the links on bladder repair in one of my previous post) and reduce the size of the opening in order to use different hardware.

 

[KeithG]

@giffenk , the concern I have is that this flange does not have an inner and outer nut....there is just the flange that was glued into the bc with the male threads protruding through the 2-inch hole, and then the elbow mated with the flange/seal and threaded "nut" of the elbow secured the elbow in place.

I may be wrong but You seem to be describing the inner and outer flange pieces that were suggested earlier, that screw together clamping the material, and then the elbow attaches with an additional piece that screws down to secure the elbow in place.

You are correct in your understanding. As per couv, the adhesive is not for strength. You appear to have a simpler (inferior?) design that depends upon the attachment of the inflator elbow to fully complete the bladder connection.

As per my description of the use of the rubber washer for the elbow connector, I would be motivated to apply the adhesive and allow it to cure before I assembled the elbow. The adhesive is for gap filling, not mechanical strength. You are trying to create a home made rubber washer with the adhesive. If you assemble before curing, you simply squeeze the uncured "adhesive washer" out of place.

 

[Zef]

@giffenk , I agree completely with what you have written, especially that this is an inferior design...my concern is that the there is nothing to keep the flange in place on my BC except the wider flat area of the flange that the fabric is supposed to be glued to. When kept flat to each other the shape of the flat part of the flange will not fall through the hole it is inserted through but reading and speaking with folks it seems like there is a danger of the flange being pulled through...especially when the corrugated hose is manipulated to dump air, as this can distort the hole and allow it the flange to easily pull through if the bond were to fail.

The more I pine over how to fix this, the more I am coming to the conclusion that I should just retire this piece of gear and purchase a replacement.

I am thinking about the following but am open to suggestions:
DGX Custom - DGX Singles Harness / Backplate / Wing Package

-Z

 

[Couv]

Let the research begin! I would definitely suggest going to a backplate and wing system if you're in need of a new buoyancy system. I'm not familiar with DGX wings, but I have purchased other items from them and find they make quality stuff for a reasonable price.

Any backplate if preferable to a jacket BC system. However, I am not a big fan of a backplate designed for doubles for use on a single tank setup-others feel differently. There are a few other option to the standard backplate. I think Deep Sea Supply Deep Sea Supply has a system for single tanks. Tobin, the owner/manager/janitor (cool hardware on SB) is the most knowledgeable person on this board when it comes to buoyancy & weighting systems and would talk himself out of a sale before selling you the wrong thing. Personally, I have a Freedom Plate that is absolutely wonderful but expensive and difficult to acquire. One of the most overlooked and reasonable alternatives is the single tank backplate sold by Vintage Double Hose Store - Vintage Double Hose Yes, it is designed with double hose regulators in mind, but it works very well with a standard regulator setup. VDH also sells wings, harnesses, etc and you can probably put together a package if you contact them.