Which of the following is NOT a desirable characteristic of hydraulic fluid?

The option of low flash point is indeed not a desirable characteristic of hydraulic fluid. Hydraulic fluids must possess certain properties to function effectively and safely in hydraulic systems. A low flash point indicates that the fluid can ignite at relatively low temperatures, which poses a significant fire hazard, particularly in the high-heat environments often found in hydraulic systems.

On the other hand, chemical stability is essential as it ensures that the hydraulic fluid does not degrade or react with components over time, preserving its performance and preventing damaging deposits. Anti-foaming characteristics are critical because foaming can create air bubbles in the hydraulic system, leading to a loss of efficiency and potentially damaging the equipment. High viscosity is desired in hydraulic fluids as it provides better lubrication under pressure and helps maintain the necessary hydraulic force even under varying temperature conditions. Therefore, it is clear why low flash point is not a beneficial attribute for hydraulic fluid.