### Answer to s-TE-m at Work Puzzle #60: Pump Part selection for thick fluid applications

Analysis
Technician rebuilds positive displacement pumps for a customer that uses pumps to transport viscous fluids.  The Tech knows customer uses their pumps to move a fluid that gets thicker when the pump applies more pressure on that moving fluid. This puzzle can trigger discussions at multiple levels: an introduction to viscosity and the simple recognition that curve (a) is not linear combined with puzzle clue (see last month for complete puzzle wording) that constant viscosity curves are linear;  the visual (approximate) slope, m, calculations, y=mx for both curves;  a discussion of curve shape implication when both models demand that Stress = (Viscosity)(Shear Rate) but viscosity changes; implication that more Stress must be applied as fluid gets thicker to have the same Shear Rate as constant viscosity fluid.  The most intense lesson includes Newton's law for Viscosity and fully developed velocity profile for flow of a Newtonian fluid entering a long pipe.

Question:
Does the Technician selected Repair Kit Pump #440?
YES OR NO