Hittade en uppgift att NBR mjuknar och sväller av RME här
http://www.biodiesel.org/docs/ffs-perfo ... bility.pdfCitat:
Military Study1 The elastomer compatibility study was performed as recommended using ASTM D 471 and D 412. Three tensile bars of each material were place in sealed, glass containers and stored at 51.7°C (125°F) for 0, 22, 70 and 694 hours.
Summary of Hardness and Swell Characteristics
Material Comments
Teflon Relatively no changes in hardness or swell
Nylon 6/6 Relatively no changes in hardness or swell
Nitrile Hardness was reduced approximately 20 percent; swell increased approximately 17 to 18 percent
Viton A401-C Relatively no changes in hardness or swell
Viton GFLT Relatively no changes in hardness or swell
Fluorosilicon Hardness is relatively unchanged; swell increased approximately 7 percent
Polyurethane Hardness is relatively unchanged; swell increased approximately 6 percent
Polypropylene Hardness was reduced approximately 10 percent; swell increased from 8 to 15 percent
The effect of B20 on vulnerable materials is diluted compared to higher blends. Some slow oxidation can occur, although it may take longer to materialize. Biodiesel also can affect some seals, gaskets, and adhesives, particularly those made before 1993 and those made from natural or nitrile rubber. It is primarily for these reasons that vehicle and storage equipment are modified. Most engines made after 1994 have been constructed with gaskets and seals that are generally biodiesel resistant. Earlier engine models or rebuilds may use older gasket and seal materials and present a risk of swelling, leaking, or failure. Fuel pumps may contain rubber valves that may fail. The typical approach is to create a maintenance schedule that checks for potential failures. Users can also contact engine manufacturers for more information.
och ur samma pdf:
Citat:
Parker O-Ring Handbook
Compatibility of Various Elastomers to Methyl Oleate
Elastomer Compound Compatibility Rating
Nitrile NBR 4
Hydrogenated Nitrile HNBR 4
Ethylene Propylene EPDM 2
Fluorocarbon FKM 1
Hifluor FKM 1
Perfluoroelastomer FFKM 1
Aflas (TFE/Propylene) FEPM X
Neoprene/Chloroprene CR 4
Styrene-Butadiene SBR 4
Polyacrylate ACM X
Polyurethane AU X
Butadiene BR 2
Isoprene IR 4
Natural Rubber NR X
Hypalon CSM 4
Fluorosilicone FVMQ 4
Material 2
Elastomers X
SiliconeMQ, VMQ, PVMQ X
Compatibility Rating
1 – Satisfactory
2 – Fair (usually OK for static seal)
3 – Doubtful (sometimes OK for static seal)
4 – Unsatisfactory
X – Insufficient Data
EPDM verkar alltså ett ok budget alternativ för statiska O-ringstätningar och NBR mjuknar och sväller (för?) mycket.
Ang bromslanger så hade jag slanger som bara släppte genom bromsvättska när (pedal)trycket var tillräckligt hög och det gav ojämn bromsverkan (och bomsar som ibland inte släppte) men det märkte jag inte vid luftning. Bromslangen betedde sig alltså lite som en tryckventil som bara öppnas under tryck.