Replacement o-ring of higher durometer

[DazedAndConfuzed]

Hi,

I've been using my Oly C5050/PT-015 forever and Olympus having discontinued their replacement a long while ago. The o-ring stretched badly to the point that I have to spend 30 min squeezing it all into place with all 10 fingers doing the work (sometimes longer, other times quite quick, all depending on luck). Good thing it is a double o-ring, since all that squeezing likely made the outer o-ring dirty or its grease smeared off.

A year or two ago, I found out their specs and ordered replacement silicone o-rings, but they were harder. They worked w/o a problem, but I am wondering if I am just lucky or will there be problems in the long term. I thought it would have been a non-issue, but then all the discussion of the cheap chinese dive lights leaking due to o-ring firmness difference. Is going from soft to harder o-ring a safe bet?

 

[DSR-3]

I think the main issue is the added force required (it goes up fast) to compress the higher duro. o-ring. This may stress the hinge and/or latch. The harder material may also be less compliant to seal on surface imperfections. Parker seals "wrote the book" on o-rings and seal design and it's available on their website. You can also find force calculators at Parker or Dupont.

 

[DazedAndConfuzed]

I do notice that the back does not sit flat while in a resting postion, seems due to the o-ring not giving in enough by the hinge area. But I don't know if the clamping for required to close the back is significantly more. And when underwater, I would think the water pressure would push on the back hard enough that there is very little stress on the hinge anymore.

I am hoping the 2nd o-ring will compensate for any issues that the harder o-rings will cause.

 

[Rooster59]

You could try putting the o-ring in hot water before you install it and snap it all shut.

 

[DazedAndConfuzed]

The o-ring is not that or oversized to prevent the back from closing. If I put it in hot water, dry it, and put the silicone grease on, it would be back to regular temperature.

What I would want to do is be able to use the orig o-ring, but that thing seem to stretch as I am applying the grease and by then, it is too big already. Even if I apply the grease real carefully w/o stretching it, I have 1 chance where everything has to go right (not let the o-ring get pushed from the hinged area, use all 10 fingers to hold the whole o-ring in its exact place, all while closing the lid) before it becomes stretched. I actually was using this method for many years on the stretchy o-ring until one time on the trip, after over an hour, I still couldn't get the o-ring in and thought why go through this every time when I can just find the orig o-ring size and buy substitute replacements (apparently, the durometer of the orig o-ring was not mentioned). But I still had to get the housing closed since I still need to use it for the whole vac and after 30 min or so, got it closed.

 

[Larry C]

Olympus Spare O-Ring for Olympus PT-015 Housing

 

[jcclink]

If you know the size of the o-ring, replace it with a buna/neoprene 50 durometer. Use generic silicon grease to lubricate. Should not be a problem.

---------- Post added September 12th, 2014 at 05:51 PM ----------

If you know the size of the o-ring, replace it with a buna/neoprene 50 durometer. Use generic silicon grease to lubricate. Should not be a problem.
KMC SEAL CO. LTD. used to be a good source for metric o-rings.

Grease on a silicone o-ring will eventually cause it to stretch/elongate, making it useless. If you need to lub a silicone o-ring use spit, not grease of any type.

Manufacturers have over complicated this o-ring issue. It's not rocket science. Most of the world works great on buna/neoprene. Colored o-rings do not improve sealing capability. They only identify the manufacturer of the housing, strobe, etc. The only reason to use a silicone o-ring is for easier maintenance - no grease required. Try to keep things simple. More time for a cold beer

 

[DazedAndConfuzed]

Olympus Spare O-Ring for Olympus PT-015 Housing

ouch, almost $50 w/S&H. cost more than a replacement camera if it gets flooded.

If you know the size of the o-ring, replace it with a buna/neoprene 50 durometer. Use generic silicon grease to lubricate. Should not be a problem.
KMC SEAL CO. LTD. used to be a good source for metric o-rings.

Grease on a silicone o-ring will eventually cause it to stretch/elongate, making it useless. If you need to lub a silicone o-ring use spit, not grease of any type.

Manufacturers have over complicated this o-ring issue. It's not rocket science. Most of the world works great on buna/neoprene. Colored o-rings do not improve sealing capability. They only identify the manufacturer of the housing, strobe, etc. The only reason to use a silicone o-ring is for easier maintenance - no grease required. Try to keep things simple. More time for a cold beer

I got 70 durometer, not sure why I got it, but apparently it is firmer. Didn't know silicone o-ring does not require greasing. I presume it works because some people don't even know what greasing is and just drop the camera in the housing and there's no leak.

 

[bvanant]

The difference in force required to seal (a 7% deflection) for a 50 vs 70 durometer o-ring is only a few percent (the modulus is the key) different and this should not be a problem in any way.
Bill

 

[DSR-3]

The difference in force required to seal (a 7% deflection) for a 50 vs 70 durometer o-ring is only a few percent (the modulus is the key) different and this should not be a problem in any way.
Bill

The increase in force is more than a few percent for even a 50 to 70 duro change, and the Olympus OEM o-ring is quite a bit softer than 50- closer to 30. I would bet that the force on a 70 duro. o-ring is over 2x the OEM part.
All that said, maybe it will work just fine. It's just not how it was designed.