Appendix A Vapor Pressures of LP Gases Vapor Pressures of LP Gases Temperature (°F) Approximate  Pressure Propane Butane –40  2  –30  7 –20  12 –10  18 0  25 10  34 20  42 30  53 40  65  3 50  78  7 60  93  12 70  110  17 80  128  23 90  150  30 100  177  38 110  204  46 A-1