PLTl-13 Low Temperature Turbidity per MIL-DTL-17111
Turbidity is a haziness or cloudiness observed in a fluid due to small, suspended, undissolved particles or the mutual insolubility of two different fluids. Particle sources may be external such as dust and water or internal such as wear metals and oxidation byproducts. Typically, turbidity caused by insolubility increases as temperature decreases. This test determines the turbidity of hydraulic transmission fluids at low temperatures.
The test sample is cooled and visually compared to a turbidity standard of an aqueous suspension of barium sulfate. If the sample is visually less turbid than the barium sulfate standard, a “pass” is reported.