L4 o-ring size?

I just read the thread about some of the L4's missing an o-ring in the bezel area and was curious as to what size o-ring should be put in? Any help will be greatly appreciated. Thanks!

I just ordered a nitrile (buna-n) o-ring kit from http://www.marcorubber.com/oring_kit.htm for $10.00

30 Sizes / 382 Pieces... if it's not in there, I should have enough for other odds & ends around the house. /ubbthreads/images/graemlins/wink.gif

I think you need to read Don's (McGizmo) posts on this thread
He has posted some useful photos

What is missing on some KL4's is a gasket not an o-ring.

Al

Thanks Al! Two gaskets for sure.

Don even mentioned that an o-ring (size 017) should do until the proper replacement parts arrive... and that's not a size included in the kit above.

Bad bad news.... I applied teflon tape to the threads of the KL4 where it threads to the body adapter and did the "blow test" and got bubbles through lens retainer ring. How is this going to fixed with a gasket?

Me too... I did 4 laps of teflon tape around the KL4 and it still bubbles like something that belongs in a fish tank. Mine is leaking from the taped junction though, not the lens retainer ring. I don't think this can be fixed with tape, I think the threaded area is to short and/or coarse for the tape to take up the slack.

I wouldn't count on teflon tape but a small O-ring should be a viable stop gap. If the O-ring is too thick or large, it will keep the collar from going on the main body far enough. The result will be that the battery tube will not contact the cathode ring and complete the ground path.

Josh,

Perhaps in loosening the components, you also loosened the bezel cap from seating the lens against the thin gasket. At any rate, you currently have a breach in the front end that needs to be fixed and is independent as you have stated from the other sealing area.

Just a side note here that probably is not a big issue but the blow test checks for positive pressure integrity. If you drop your light in water to any depth, negative pressure integrity is what you need to be concerned with. In most sealing designs, pressure differentials are maintained with a good seal regardless of positive or negative pressures. This is however not always the case. Many devices designed for diving will not seal properly in a negative pressure environment but their seal against positive pressure actually increases as the pressure increases. The gasket seal between the lens and reflector is just such a case where as the pressure against the lens increases, the compression on the gasket increases as well.

You could hold the lens and gasket with your finger against the reflector body and take the light underwater and with enough depth, the lens will stay in place due to the pressure and you will have a great seal until you return topside and have the lens fall off. Blowing bubbles with the lights does indicate a good seal if you can't get bubbles but it doesn't necessarily tell the whole story or in some cases insure proper function with submersion.

Sorry for the long aside here.

- Don

Good points... I understand what you're saying about the positive vs. negative pressure integrity. But as you said, I don't think it's the issue with this particular problem. I didn't have to blow very hard to get this thing to bubble. I'm quite sure that water would find it's way into the light in a decent rain. Just a simple case of a missing gasket (o-ring, whatever). Sure is annoying to spend that kind of $ and have such a stupid little problem though...

[ QUOTE ]
McGizmo said:
... a small O-ring should be a viable stop gap. If the O-ring is too thick or large, it will keep the collar from going on the main body far enough. The result will be that the battery tube will not contact the cathode ring and complete the ground path....

- Don

[/ QUOTE ]

Don,

I'm using a fairly thick o-ring from a TACM. I lubed it and tightened the bezel parts until the gap was about 1/32". Battery tube/cathode ring contact is OK. (I tested by first partly unscrewing the entire head, then fully tightening the Z52 {I replaced the Z57}, then gradually retightening the head until the light turned on. It turned on well before the fully tightened position). The light has proven to be fully waterproof.

Is there any reason to worry that this is not a permanent or at least very longlasting seal?

I opened the bezel ring and the gasket is there but I've considered adding a thin 0-ring below the base of the threads for insurance. Or should I just re-loctite it; what do you think?

Thanks,

Brightnorm

Brightnorm,

It sounds to me that you have a viable alternative and there is no reason I can think of not to expect good service from your solution. Ozone and time can cause gaskets and O-rings to break down and you are in a position to monitor the condition of your seals and replace if and when necessary. On most UW dive gear, seals and gaskets are replaced annually on general principle. I for one like to have access to my gear so I can monitor its condition and replace components as necessary. There is a user responsibility associated with an open system but by the same token the user has control over the maintenance and well being of the system.

- Don

[ QUOTE ]
McGizmo said:
Brightnorm,

It sounds to me that you have a viable alternative and there is no reason I can think of not to expect good service from your solution. Ozone and time can cause gaskets and O-rings to break down and you are in a position to monitor the condition of your seals and replace if and when necessary. On most UW dive gear, seals and gaskets are replaced annually on general principle. I for one like to have access to my gear so I can monitor its condition and replace components as necessary. There is a user responsibility associated with an open system but by the same token the user has control over the maintenance and well being of the system.

- Don

[/ QUOTE ]

Thanks Don,

BN