68477-99-6 EINECS 270-782-8 Gases (petroleum), isomerized naphtha fractionater, C4-rich, hydrogen sulfide-free Gases (petroleum), isomerized naphtha fractionator, C4-rich, hydrogen sulfide-free Gases, petroleum, isomerized naphtha fractionater, C4-rich, hydrogen sulfide-free Isomerization butane isomer hydrocarbon stream