Coolant inside large diesel engines contains anti-corrosive additives and some of these can damage FKM. Because of this, the higher cost product, FFKM, is sometimes used. However it is known that leakage problems can occur due to its poor elasticity.
AFLAS® has similar chemical resistance to FFKM and better elasticity than FFKM. AFLAS® not only has a cost advantage but also a longer service life.
FKM will harden if it comes into contact with steam which contains anti-corrosive, even if the steam contains only a very small amount of anti-corrosive. AFLAS® has excellent steam resistance and has been found extremely reliable in this application.
O-rings are exposed to corrosive gas like H2S, high temperature steam or basic mud in this application. Rubber parts made of AFLAS® survive longer under these harsh conditions.
AFLAS® can be extruded. AFLAS® hoses provide excellent chemical resistance which is not possible with FKM. It is not only used in automotive applications but also in the chemical industry.
In Japan, blow-by gas from diesel engines used to be released into the surrounding environment, but in order to reduce hydrocarbon emissions, Blow-by gas must now be returned to the intake line.
The turbo hose between the turbo charger and the intercooler is made from silicone rubber currently. Blow-by gas contains a small amount of engine oil mist and silicone rubber has poor resistance to oil. Therefore engine manufacturers are looking to replace it with fluoroelastomers.
Engine oils contain several chemicals, dispersants, oxidation inhibitors and abrasion inhibitors. Some of these additives attack FKM at high temperatures and make FKM's surface brittle. Turbo charged air contains a small amount of engine oil mist, which contains these additives. After prolonged exposure, FKM turbo hoses may crack. AFLAS® has excellent resistance to these additives making it a better choice for this application.