We have analyzed a hydraulic oil (Shell Tellus T 15) and have found higher Phosphorus (And Si) than excpected in this oil. The Phosphorus content is app 3000 ppm (Normal is 4-500 ppm).
Shell claims it most likely is an additive that contains: 6-6.6 % phosphorus, 11,4-12,4 % sulfur and 7,6 - 8,1 % zinc. Treat rate 0,84 %.
We do also have app. 150-200 ppm of Si in this oil (oil is used for flushing new hydraulic systems). Microscopy shows few particles (non dust like) so the Si is most likely also from a product.
Does anybody know what substance this might be?
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