In order to build an apparatus, I kindly ask for people to share their experience with resistance of different o-ring materials e.g. PTFE or FFKM to alcohols. In my UHV experiments, I will use ethanol, methanol, benzene and other vapours as well as gases like hydrogen and carbon monoxide. In order to build the apparatus, I need valves which are chemical resistant. Although I found valves which seem well suited for the experiments because they have metal sealings, I would be very glad to hear from other people if there is some decision support concerning the o-rings.