16 replies to this topic

[Marc Furth]

I keep seeing question all over this Forum with the need for replacement o-rings. I thought
I’d give my input here for those who are having trouble finding exact replacements from their
housing manufacture and my comments about them.

First I would always recommend buying your replacements through your housing manufacture. But in those rare cases when they can’t be purchased. You can buy most o-rings right over the counter at a local area store .

I believe that 99% of all o-rings are standard sizes. It wouldn’t make sense for any company making a housing to use anything but what could be bought over the counter. O-rings are manufactured in a wide range of sizes and in many different types of materials for all types of applications. Buna 70 is the most widely used type of o-ring in camera housings and has proven to be cost effective and reliable. When kept clean and lubricated with silicone they will last for years.

You can how ever have problems with o-rings when the are kept under compression for long periods of time. They will lose their effectiveness and will remain compress if they are compressed continuously. In my opinion it’s best to keep your housings ports lose while their being stored for months on end. It’s not that much of a problem with mechanical type controls. They don’t have a great deal of pressure on them when their in a static mode.

Their is a misconception with newbees that if you use a lot of silicone on your seals that it will
seal better, not so. The main purpose of silicone is for protection of your o-rings and lubrication.
The sun’s ultra violet light, saltwater, pool chorine, and other elements will eventually dry out your o-rings and cause them to crack and fail. It also let your controls and ports move easily while under pressure .A light sheen applied is all you need to keep your o-rings protected.

So where can I get my o-rings locally ? Most bearing stores sell seals and that includes o-rings. The can be found under automotive applications or just look up Bearing stores in your local yellow pages. I have found that these stores are most helpful and willing to size your replacement. Just bring in you old o-rings, and or your housing to. They have o-ring measuring charts and or a stretching device that can deter men the exact size. The usually come in a package of 5 or more and are a fraction what you would pay from your dealer.

Marc

[rstark]

Good suggestions. I also recomend contacting your housing manufacturer and asking the exact sizes for all orings in the housing. THis is good information to have in the case the manufacturer goes out of business. If you do know what size you need then a good source is EPM

[ikelite]

"O" ring replacement is more complicated than size alone. Buna N and neoprene compounds can cause stress cracking in many plastics because the elasticizer may migrate from the "O" ring when or if it is squeezed tightly.

[marscuba]

If you want a good idea of how many different kinds of elastomers there are out there, take a look at the Parker O-Ring Handbook.

I stand by my previous recommendation of using only manufacturer supplied O-rings and grease unless you have the capability and testing lab (durometer, compound analysis) to determine the exact materials.

[bvanant]

I must agree with Matt, we have a lab, can measure durometers and ID materials pretty easily but I would always try to get my O-rings from the manufacturer. I know they get them from Apple but unless the mfg goes out of business, I would buy them direct.
Bill

[Marc Furth]

Once again my suggestions were first check with your camera manufacture for replacements.
Then you could exercise your option to buy them from your local bearing store if you can’t
locate them.

I have not bought all that many housings from different manufactures. I have made my own housings for the past 14 years. The last housing I bought was from Ike last summer for my Nikon 5000. I was not making push buttons controls at that time and was looking to get in the water immediately. I sold it after a month of use because of problems with white balancing. This had nothing to do with Ike’s housing. So I’m not really an authority about what type of o-ring material other manufactures are using. I have however worked on many other camera housings in the past and have not really seen any other material but Buna type o-rings.

I have never had any problem like Ike has suggested. All of my housings are made from PVC or aluminum with acrylic end plates. This might be a problem with materials such as polycarbonate which I believe are what Ike’s clear housings are made from. I have replaced his port seals with Buna N 70 o-ring material and have not had any problems between the Port and the acrylic end plate that it sits on. I believe both of these are made from the same acrylic material. Ike, you’ll have to correct me if I’m wrong about this ?

I’m very much aware of a host of other materials that are used for o-rings . I do have an account with Marco Rubber, a major manufacture of o-rings, and have bought 1000's of rings from them. I always talk to my rep. for their recommendations on material and o-ring design.

Because I don’t stock any other o-ring except for what I’m making at the moment, I always buy a sample from my local bearing store first for testing, then buy them in quantity later from Marco Rubber.

Marc

[marscuba]

Marc, you and bvanant are probably the only two who have the capability and expertise to do measurements and compatibility testing for O-rings.

For the other 99% of the people on the board, I still recommend to purchase the manufacturer's supplied O-rings and grease. What is the price difference, a few rolls of film or one or two dives?

[Jola]

What is the effective life of an O-ring? I have an Olympus PT-005 (C-4000Z) and am still using the original O-ring after two years. The housing has only been used for about 30 dives, and I have made sure to take good care of the O-ring. But I didn't know about the possible compression problem during storage and have kept it in the housing with it closed.

The problem is that it is very difficult for me to get original replacements, so it is not as simple as just being conservative and replacing it.

[wetpixel]

Anyone following the o-ring "debate" on uwphoto? What a horrible waste of time. I don't follow that list because of threads like that. Too many egos, it seems.

[Marc Furth]

I Just purchased a large quantity of small o-rings from Marco Rubber.

On the package their is a batch number, current date 2002, and expiration date 2017.

I would believe this is for optimal storage conditions.

Egocentric,
Marc

[bvanant]

Eric:
Not only too many egos but too many guys who don't understand physics. I was laughing pretty hard trying to understand how the pressure of the air inside a housing was different whether or not it had a camera in it.

Amusing, but thanks for pointing it out, I had given up on the uwphoto board for the last few months.
Bill

[bvanant]

Marc:
I guess that an expiration date for an 0-ring is the time it takes to for it to get too hard to seal well. I was curious as to your choice of Buna-n, I would have thought that the Viton or silicone 0-rings would have had much better compression set, or is that not an issue?
Bill

[MikeO]

Eric:

Though the UW-Photo list sometimes requires liberal aplication of the delete key (having an e-mail program that organizes the posts into threads that can be deleted en-masse is something that really helps), I still believe it is one of the best places for information sometimes. For example, I see that you posted a link to Barry Lipman's copyright page. I imagine you read about that on UW-Photo. Granted, Barry did it just as an attempt to bring one of those never-ending threads to a merciful conclusion, but still, I think it's a good example of the list's utility.

Mike

[Marc Furth]

Here is a good link to a comparison chart on different material, and their use.

http://www.marcorubb...terialguide.htm

Marc

[wetpixel]

Though the UW-Photo list sometimes requires liberal aplication of the delete key (having an e-mail program that organizes the posts into threads that can be deleted en-masse is something that really helps), I still believe it is one of the best places for information sometimes.

Mike - I agree! There is a great deal of information to be found on that list, if you have the time to skim through the messages. I find it overwhelming, myself, but I still get to it every few weeks.

In my uwphoto archives, I'm sure there is a lot of good information that is sitting unread, unfortunately.

[marscuba]

Jola, you can easily purchase replacement O-rings from me or other sources (Allen, etc.) who post here.

Regarding UW Photo, there is a ton of great info as well as advice from pros that you wouldn't find on a BBS. The real problem now is that there is no archive and no real list manager these days.

[Reefkeep]

I would like to purchase extra O-rings for the UK Germany housing, do you know anyone in the US that sells them?