What is C.I.R.? A type of rubber?

[Andy22]

I have a drawing that specifies 1/8" thick C.I.R. for a flange gasket material. I suspect that it is actually natural rubber but what does C.I.R. stand for?

 

[berti]

Hi andy22,

only a guess. If you think it it natural rubber actually then C I R could -could !!- mean cis isoprene rubber which is the synthetic twin of NR.

HTH Berti

 

[aholloway]

Per ASTM D1418 (Vol 9.0) CIIR is chloro-isobutene-isoprene (chlorobutyl). Maybe someone left out the second "I"?