O-ring hull seal question

[typ 202]

Howdy all,

I'm modding my typ 202 to use an o-ring to seal the dry hull similarly to what you see on the German and Swiss sites. I need to know just how much of the o-ring needs to project past the horizontal sealing surfaces. In otherwords, just how much clearance do I need between the two surfaces for a good seal yet still be able to assemble the parts somewhat easily.

Thanks,
Mike

[steveuk]

If you are talking about

If you are talking about the big o ring that goes around an end cap that pushes into an acrylic tube all I can say is the one I bought is so tight I have to wet it to get it to slide in.

I wouldnt say getting the end cap on and off is easy at all. Maybe that gives you an idea of what you are aiming for. I can only assume it is made this tight for a good reason.

[bill rogers]

I know how typ 202

I know how typ 202 feels. Earlier this year I bought a Thor Permit from Atomic Subs and haven't had any success in stopping leaks into the WTC. The end cap (battery end) is a loose fit and the O ring doesn't give a good seal. I've tried putting silicone sealing tape in the groove under O ring to get a tighter seal but that didn't work. When I sealed the joints between both end cap flanges and the WTC with GE Silicone II, I still got water into the cylinder after a 20 minute run. That made me wonder whether the shaft seal or the push rod seals could be leaking. It's a good thing I live in California because I was still able to go into the pool today to retrieve the boat off the bottom. Any suggestions would be greatly appreciated.

[m. munger]

Ah, O-rings....

Check out]Engineering Fundamentals -

Ah, O-rings....

Check out]Engineering Fundamentals - O-Rings[/url] for the answer to all your O-Ring questions....

Hope this helps, good luck!

Matt

[Guest]

Bill,
There may be more than

Bill,
There may be more than one leak. Leaks can usually be fixed if you find out where they are. It may be a good idea to put some air pressure into your WTC, and dunk it in the bathtub, to see where the air bubbles are coming out. That should tell you where the water is getting in. I just found a slow leak this way, after I took the WTC out of the water. It was bubbling around a brass tube going through the endcap, that I had not completely sealed.

[steveuk]

Any suggestions would be greatly

Any suggestions would be greatly appreciated.

Make yourself a pressure test inlet.
Drill a hole somewhere in the end cap and fix a piece of brass tube in, and attatch a piece of flexible tubing. Stick the sub in a test tank and blow into the tubing - you will soon see where the bubbles are coming out. Fix the leak, don't forget to make a cover seal to go over your brass tube pressure test inlet.

[Rick Teskey]

.020 ijnterferance should do it

.020 ijnterferance should do it but if morre interferance is needed you can shim under the o ring with a strip of electric tape
Rick

[typ 202]

Gentleman-- Thank you all for

Gentleman-- Thank you all for your replies. I've been incrimentally filing the groove down until I can with a good bit of force push the parts together. I made sure to bevel the edge of the receiving or female part and lightly silicone greased the male part and o-ring. Slides in with a good push. The seal is water-tight as I've tested it under pressure as suggested. This is the first time I'm trying this method of sealing my hull as in the past I've made my own WTC's of thick-walled schedule 40 PVC pipe with Lexan endcaps and silicone gaskets. Always put a bit of brass tubing and silicone fuel tubing mounted to the endcap for pressure testing before each run. I use Skips shaft seals exclusively and have never had a leak. Their design also allows you to pressurize the hull pretty significantly without any blow-by.

I'll have to check out that website too. Anyone have any suggestions as to a website regarding basic electronics? I need to learn a bit about electronics so that I can wire things up with greater confidence that I'm doing it right.

[typ 202]

Just read through the information

Just read through the information on the engineering site. Very informative. I hadn't thought much about the gland (groove) width. Needs to be about 1.5 times the cross sectional width of the o-ring to allow for effective compression deformation of the o-ring.

Mike