What is true concerning lube oil coolers?

The statement that the pressure of the oil is greater than that of the cooling water is true in the context of lube oil coolers. This design ensures a couple of important operational advantages. First, having the oil at a higher pressure than the cooling water helps prevent any potential contamination of the oil by cooling water, which could compromise the lubricating properties of the oil and lead to equipment failure.

Additionally, the increased pressure of the oil facilitates improved heat exchange performance within the cooler. As the oil flows through the cooler, the heat is transferred to the cooling water, which then carries this heat away, maintaining the proper functioning temperature of the lubrication system.

In contrast, the other options imply scenarios that are not typical for lube oil coolers. If the cooling water pressure were higher, there would be a risk of water entering the oil system, which could lead to issues like emulsification or degradation of the oil. The notion of equal pressures does not apply because it would detract from the overall efficiency and protective features of the system. Lastly, in standard practice, oil and water typically flow in countercurrent directions rather than the same direction, which maximizes the temperature gradient and enhances heat transfer efficiency.