Rubber material

[Joe683]

I have been tasked to find a suitable rubber to replace "DTD 625" on aircraft fuel tank sealing washers. Any recommandations regarding working temp, cost, life span etc would be extremly helpful.

 

[israelkk]

What is the spec of this rubber?
What kind of polymer? Nitrile? Butyl?, etc.

 

[Joe683]

Well thats what I mean really, what would you recommend as the most suitable regarding its application (fuel tank sealing washer's) taking into account such things as cost, life span, working temp etc. The rubber material itself would be 7.25mm thick, 45mm outside diameter and 32.5mm inside diameter once cut to size. I already have a list of rubber materials as follows: Flurosilicone
Isoprene
Chloroprene(neoprene)
Butyl
From the list if any one knows the most suitable and why you would recommend that one I would be most grateful.

 

[tom1953]

From a fuel resistance standpoint, of the four polymer you list, fluorosilicone would be the best, neoprene would be fair, and butyl and isoprene would be poor. Fluorosilicone is very expensive compared to the other three, however.

Other polymers (NBR, HNBR, urethane, for example) would have good/very good fuel resistance but not the excellent heat resistance of fluorosilicone. The best polymer/rubber would depend on all the requirements considered together. I'd think there would be a detailed specification for any materials used in aircraft.

FYI, there is a "rubber engineering" forum (

http://eng-tips.com/threadminder.cfm?pid=335)

that may be a good place to post this inquiry, preferably with some specifics regarding specification/property requirements.

Hope this helps,

tom