This is just an opinion, but those look an _awful_ lot like kalrez orings, which are chemical resistant. Once upon a time I worked at a silcone manufacturing plant, we used these a lot, along with viton orings in high temp, volatile applications.
Maybe try here?
http://www.marcorubber.com/sizingchart.htm
http://www.marcorubber.com/kalrezindustrial.htm
If you know the rough (nominal) size for the ID/OD, then you can probably match it up pretty easily. The charts go up over 18", so there's probably one in there that's the right size.
This is one of the better pics I found on a quick search, its a bit large for the application though.
Maybe try here?
http://www.marcorubber.com/sizingchart.htm
http://www.marcorubber.com/kalrezindustrial.htm
If you know the rough (nominal) size for the ID/OD, then you can probably match it up pretty easily. The charts go up over 18", so there's probably one in there that's the right size.
This is one of the better pics I found on a quick search, its a bit large for the application though.
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