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Replace Bison Tube Seals with EPDM


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Don't know how else to disclose this info., but thought it might be useful. If this is the wrong place to put this, please email me via my account (I don't spend much time browsing the fora).

 

I own a micro-cache (Bison tube or a cheap knock-off) located in a very wet, nearly submerged spot (in rainy Woodinville, Washington, everywhere is wet). The original container, like many others I have found, leaked badly within the first few days of being put out. I replaced the original O-ring with an EPDM O-ring, Size -014 (they are available from www.mcmaster.com), and the tube has not leaked since, through a very wet winter and many more finds.

 

- btrueblood

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Had to google what EPDM stands for...

EPDM rubber (ethylene propylene diene monomer rubber)

 

I have noticed all along that the o-rings found on bison tubes are of particularly poor quality - they look as if they have perished even when brand new. I have thought of using regular o-rings found at auto spares shops. I wonder if they are EPDM?

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Looks like there are two different 'grades' depending on what you want to use them for...

 

American National Standards Institute (ANSI), Food and Drug Administration (FDA), National Sanitation Foundation (NSF) -65° to +300°F 9561K15 $5.36 per Pack of 25

 

American Society for Testing and Materials (ASTM), Society of Automotive Engineers (SAE) -65° to +212°F 9557K466 6.63 per Pack of 100

 

I'm gonna get one of each...

 

Anyone need any o-rings? ;)

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On 6/19/2008 at 1:48 PM, btrueblood said:

I replaced the original [bison tube] O-ring with an EPDM O-ring, Size 014 (they are available from www.mcmaster.com), and the tube has not leaked since, through a very wet winter and many more finds.

 

Thanks for posting this! I'm going to add these to my caching repair bag :)

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48 minutes ago, fizzymagic said:

Silicone is better for those things.

 

I've heard that silicone is not water vapor tight, so the contents may get wet. Some silicone-sealed cache jars are known to always be moist inside.


Polytetrafluoroethylene (PTFE) could be another candidate.    https://www.thehopegroup.com/blog/advice/o-ring-material-guide/

 

I have excellent results using plumber's tape (teflon) wrapped around the threads of the bison tube. Only problem is that it tears off gradually.

Edited by arisoft
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21 minutes ago, arisoft said:

 

I've heard that silicone is not water vapor tight, so the contents may get wet. Some silicone-sealed cache jars are known to always be moist inside.


Polytetrafluoroethylene (PTFE) could be another candidate.    https://www.thehopegroup.com/blog/advice/o-ring-material-guide/

 

I have excellent results using plumber's tape (teflon) wrapped around the threads of the bison tube. Only problem is that it tears off gradually.

 

What luck!  The site mentioned in the OP sells all of the materials mentioned so far, including plumber's tape.

I've never tried to delve into specific O-ring material. I cross my fingers and hope to find an O-ring that fits at all, which may be more thin or fat than I might have hoped, and almost always seems a lot smaller than I'd hope.  But it works until the O-ring vanishes (within a handful of finds), then I try to find another in my caching supplies.  So the only parameter I've ever used as it applies to O-ring type, is having a lot of them on hand. 

 

Edited by kunarion
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Buena-N  or Viton-C are the best O-ring material ( Viton is pricey and mostly for high temp. applications).

I've used Buena for years with great success on all sizes  of  bison and also on match holders ( which I hide mostly ) where the flat gasket is problematic.

I usually pick them up at Home Depot or Ebay.......I think I carry 3 sizes.

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