Using Latex Balloon to seal tube instead of Teflon


#1

I use a latex balloon 'strip' to adjust the tightness of the 0-ring seal in the e-tube. Here is what I mean:

The balloon I chose is pretty big. It's the 'clear' one and measures 7" long (the white one is a 'normal' balloon. 5" long. It is just for comparison)

I sliced up the balloon in wide(ish) strips. One end of my tube fits tighter than the other end, so for it I used a strip from closer to the opening. It stretches more and fits the tighter end better. Obviously I used a strip from the middle for the loose end.

I put the strip around the end cap like this.

I found it easier to place if the strip is a bit wider and I leave the excess around the edge.

I don't have a picture (because I just thought of this now) but use a q-tip to add a little grease before placing the strip. Don't put much on though because it is CRAZY HARD to place the strip when it is covered in grease. :D

Side view!

Now place grease liberally around the o-ring as usual.

Ding! Nice tight seal.

If it isn't tight enough, use a strip with a larger circumference. You can also use more than one strip if it is still not tight enough. I doubled them up when I was first trying this, before it occurred to me to use a larger strip. Doubling works just as well, so its a good option if you can only get smaller balloons.

I think the latex will eventually be broken down by grease, but for me the teflon tape broke down quite quickly and needed to be redone. I think this will last longer, but only time will tell!


Water in E-Tube
#2

Hi Darcy:

Thanks for posting this. So last weekend I tried cutting some slices out of a latex glove, and found it to be a very frustrating process. Eventually I just decided to see if a rubber band would do the same thing. I dug out the big Office Depot variety pack of rubber bands that was sitting in my desk, and pawed through it until I found a couple of bands that were about the right diameter and width and were of varying thicknesses.

I pulled apart my ROV, stripped off all the old Teflon tape, and played around with greased rubber bands until I figured out the correct thickness needed. Put everything back together, and did a vacuum leak check of the tube. It wasn't perfect, but was way better than before.

I'm using the Mityvac pump that has been recommended before, and with the rubber bands under the O-rings, it takes about 3.5 minutes for a vacuum to bleed from 11 to 10 inches Hg. With the teflon tape it was about 1-1.5 minutes. I'm looking forward to taking this out into deep water for the first time (it's only been in shallow water so far) to see if this is "good enough"

Like you, I question whether the rubber bands will hold up over time, but they're pretty easy to change, and I know Eric is working on a new endcap design that will use a bigger O-ring.

-Walt


#3

@ Darcy ,Walt,

In fresh water no biggie Salt water whole nother bag of worms we used to "pot" helmet speakers in condoms and they did not last long a few dives even though they just got some "splash " from water in the neck dam . Polyurethane surgical gloves would be more resistant . There are a number of different ways to tighten O-ring seals you have found one " under shimming " aka Stack Seals ,another is side shimming with a flexible but "hard" shim ,inside outside it matters not and the shim can be split made out of anything from milk jug ,soda bottle ,phenolic ,acetate you name it . By side shimming you cause the O-ring to stand more "proud " in the groove by limiting it`s side squash on compression , this is a far more permanent solution and way ,way more resistant to salt water !


We used to get really funny looks when we bought rubbers by the gross ! Commercial Divers are a strange bunch and we always got a big laugh out of the saucer eyed looks we got picking up the order from the drugstore ROLFLMAO !!!!


#4

Really good idea! Going to try this.