Chemical Resistance of Candidate Accelerometer Cable Sheathings to Fluids Used on CF Ships

The Ship Noise Group DREA is studying ships vibrations radiated into the ocean. This study is part of the Ship Noise Management System project whose goal is to predict a ships signature from within the ship. To monitor the vibrations, accelerometers are to be mounted m the bilge spaces of CF Ships. There was concern that the fluids in the bilge space might degrade the accelerometer cable sheathing and affect the accelerometer output. The Materials Chemistry Group DREA was asked to aid in the selection of an accelerometer cable sheathing with the required resistance to bilge fluids. The sheathings, taken from Vibra Metrics, PCB Piezotronics and Wilcoxon Research accelerometers, were immersed in six fluids and their chem1cal resistance evaluated by monitoring weight gain. The six fluids were 3-GP-24 aviation turbine fuel, MIL-H-5606 hydraulic fluid, MIL-L-23699 synthetic lubricating ml, MIL-L-9000 diesel lubricating ml, 6 AFFF in water, and ethlyene glycolwater 1 1. The urethane based sheathings had good to excellent resistance to all fluids except the synthetic lubricating oil The copolymer sheathing exhibited only fair resistance to the aviation turbine fuel and the hydraulic fluid. As the major organic constituents of bilge fluids are fuels and hydrocarbon based lubricants, polyurethane cable sheathing is suitable for use in bilge spaces.