Compatibility of Single Hydraulic Fluid With Military Specification Fluids, Seals and Metallurgy.

This report documents the results of compatibility studies designed to determine the compatibility of Single Hydraulic Fluid SHF with currently used military specification hydraulic fluids MIL-H- 6083, MIL-H-46170, elastomer seals, and hydraulic system metallurgy. The evaluations consisted of subjecting various elastomer samples including nitrile, polyacrylate, and fluorocarbon to SHF by itself and SMF mixed at various percentages with MIL-H-6083 and MrL-H46170, determining their volume and hardness change, then immediately subjecting them to immersion in SHF. The elastomers were again examined for any net change in hardness and volume after the sequential immersion. Finally, SHF compatibility was tested with the elastomers and the metallurgy in each others presence to determine if any decomposition in elastomers or fluid or metallurgy occurs. It was found that SHF is fully compatible with MIL-H-6083 and MIL-H-46170 and the existing metallurgy. SHF was also found to be completely compatible with 5 of the 6 elastomers tested. The only exception was fluorosilicone which exhibited anomalous behavior in the sequential fluid testing. It performs well in SHF by itself and when immersed in fluid mixtures of SHF and MIL-H-6083 or MIL-H-46170, yet it exhibited significant shrinkage when subjected to SHF after immersion in the other fluids. This behavior cannot be explained in the scope of this evaluation. Further examination will be required to determine if fluorosilicone seals can be used successfully with SHF. AN