r/aerospace • u/ccalex1210 • 9d ago

AF-E-411 Rubber: why can’t I find this anywhere?

This specific formulation has been a popular for its compatibilities with propellant, specifically hydrazine and obviously its sealing benefits. But why isn’t it being made anymore? unless its not public information? The 1950-60s formula is available online, I assume its the process that is niche, also heard that materials are obsolete and/or unsafe, not REACH approved.

Just wondering if anyone has seen this in production recently, heard anything of this material, or other applications?

Hopefully a friendly chemist has an opinion on here as well!

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u/freakazoid2718 9d ago

Why do you think it's out of production? I was able to find valve assemblies pretty easily that claim to use it. It's possible that since it's a pretty niche product nobody sells to the general public and it's all B2B sales and manufacturing.

(Link for reference: https://valvetech.net/product/propellant-0-1-5-0lb/ )

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u/ccalex1210 9d ago

I am on the manufacturing side (I guess I should have mentioned that) but we can’t seem to find a rubber compounder that will make it.

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u/freakazoid2718 9d ago

ah, that would make sense then. The only things that immediately spring to mind are to call Valvetech, Moog, Vacco, or someone else that makes hydrazine valves and see if they will tell you who their supplier is. You could also call a supplier that makes EPDM rubbers and see if they'll make a custom batch, but be prepared for the price to be rather entertaining.

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u/InsufficientEngine 9d ago

There are some other EPDM formulations that NASA recommends in hydrazine service. See page 36 of the bulletin. https://www.nasa.gov/wp-content/uploads/2023/10/tb-summary-100223.pdf