As a former seal specialist for a valve manufacturer, i guess this is my area! O-rings are very suited to our uses, we just have to be careful what material to use. Silicone is about the best & most widely suitable for -15 to 200'C. Other materials vary, even to within blends. For example Viton A is not recommended for use with steam where as Viton B or Viton GF is. Viton is good for about the same temperatures as Silicone. Other seals such as EPDM and Nitrile are readily available, but are less tolerant to chemicals (Natural Rubber does not like Oils for example) An excellent compatibility website used in the industry is available here http://www.coleparmer.com/techinfo/ChemComp.asp Hope that helps! Craig > There is a discussion on a message board about the use of O rings in model > steam engines. > Both the types and where they are, or are not, suitable, together with the > advantages /disadvantages of them compared to other forms of seal. > > What opinions do members here have? > > Alan > > > > MODEL ENGINEERING DISCUSSION LIST. > > To UNSUBSCRIBE from this list, send a blank email to, > modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the subject > line. > MODEL ENGINEERING DISCUSSION LIST. To UNSUBSCRIBE from this list, send a blank email to, modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the subject line.