Following some lines of investigation which I have been following up:
Short extract from the European Aviation Safety Agency 2008 report on the Safety Implication of Biofuels in Aviation:
… . most flexible hoses or junctions are made from nitrile rubbers or close derivatives (NBR, H-NBR and X-NBR)…….. These rubbers yield a good resistivity against typical, non-alcohol admixed gasoline types. ….As soon as larger amounts of ethanol are present in the gasoline the picture changes, especially for the NBR materials resistance against this mixture.
As a conclusion it is recommendable to exchange nitrile rubbers as not being sufficiently qualified for their usage in the aviation industry if in contact with ethanol-admixed-gasolines, against more resistant materials.
A compatibility table in the report shows that ECO rubbers offer full resistance against Ethanol, although not specifically tested in a combined Fuel-Ethanol mixture environment.
NBR is commonly known as "nitrile rubber"
Trade names for NBR are e.g. Breon, Chemigum, Elaprim, Hycar, Nysyn, Butakon
ECO is "epichlorohydrine rubber"
Trade names for ECO are e.g. Hydrin, Herclor H, Gechron
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Extract from a Stromberg Dealer catalogue picked up by Klaus Schlüter at the Stuttgart Classic Car Exhibition last weekend:
Stromberg CD175 Diaphragms:
O.E. Type (Hydrin based)
Budget Aftermarket Replacement (Nitrile based)
************************************************** *********
Everyone to draw their own conclusions and decisions!
Drew
Short extract from the European Aviation Safety Agency 2008 report on the Safety Implication of Biofuels in Aviation:
… . most flexible hoses or junctions are made from nitrile rubbers or close derivatives (NBR, H-NBR and X-NBR)…….. These rubbers yield a good resistivity against typical, non-alcohol admixed gasoline types. ….As soon as larger amounts of ethanol are present in the gasoline the picture changes, especially for the NBR materials resistance against this mixture.
As a conclusion it is recommendable to exchange nitrile rubbers as not being sufficiently qualified for their usage in the aviation industry if in contact with ethanol-admixed-gasolines, against more resistant materials.
A compatibility table in the report shows that ECO rubbers offer full resistance against Ethanol, although not specifically tested in a combined Fuel-Ethanol mixture environment.
NBR is commonly known as "nitrile rubber"
Trade names for NBR are e.g. Breon, Chemigum, Elaprim, Hycar, Nysyn, Butakon
ECO is "epichlorohydrine rubber"
Trade names for ECO are e.g. Hydrin, Herclor H, Gechron
************************************************** *********
Extract from a Stromberg Dealer catalogue picked up by Klaus Schlüter at the Stuttgart Classic Car Exhibition last weekend:
Stromberg CD175 Diaphragms:
O.E. Type (Hydrin based)
Budget Aftermarket Replacement (Nitrile based)
************************************************** *********
Everyone to draw their own conclusions and decisions!
Drew
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