I am looking for a regulator diaphragm for CO2 and found that Polyurethane is unsatisfactory for CO2 in the "Gas Compatibility" of the Design+Safety Handbook from Scott Speciality Gases. However, at the same time I found that polyurethane is SATISFACTORY for CO2 from another article, the web address of which is attached here http://www.asge-online.com/pdf/GasCompatibilityTable.pdf. It is from ADVANCED Speciality Gas Equipment. All other data in the two tables are almost the same except for CO2. Can someone tell me which one is correct? Thanks. Jianwei