Long Life Elastomeric Aircraft Hydraulic Seals. Part I2

The continued development work of long life elastomeric hydraulic seals for -65 to 450 F4000 psig service has shown very encouraging results. By optimizing compounds, which were based on commercially available elastomers, it has been possible to meet several goals within this temperature range. Dynamic evaluations which were designed to test specific temperature range have shown 1 Acrylonitrile compounds have been developed for long service life in MIL-H- 5606B fluid over a temperature range of -65 to 275 F. 2 Acrylonitrile compounds have been developed for long service life in MIL-H-83282 fluid over a temperature range of -40 to 275 F. These compounds have a minimal 100 improvement in dynamic service life over present MIL-P-25732 compounds. 3 Polyacrylates show good potential for a service temperature range of -40 to 325 F in MIL-H-83282 fluid. Some potential limitations require further investigation in this area. 4 Available fluorocarbon elastomer compounds fabricated into hydraulic 0-ring seals have been shown to have long life sealing capabilities over a -10 to 350 F temperature. At 400 F the life of these seals are less than 1000 hours. Initial results indicate that greatly improved broad temperature range seals can be developed through compound improvement of the low temperature experimental fluorocarbon elastomers by increasing extrusion resistance and reducing high temperature compression set. This approach coupled with the development of improved anti-extrusion devices will be investigated under future programs.