What additional purpose do manual pressure reducing throttle valves serve?

Manual pressure reducing throttle valves primarily function to regulate and maintain downstream pressure within a system, ensuring that the pressure is kept at a safe and efficient level for operation. The correct choice highlights an important additional purpose of these valves, which is to control lube oil flow.

In many systems, particularly those involving machinery or equipment that requires lubrication, it's crucial to manage the flow of lube oil effectively. The manual pressure reducing throttle valve can help in modulating the amount of oil being fed into critical components, ensuring that adequate lubrication is provided while preventing issues that can arise from either excessive or insufficient oil supply.

This controlled flow helps in maintaining an optimal operating temperature, reducing wear and tear on moving parts, and enhancing overall system reliability. Thus, the importance of these valves extends beyond just regulating pressure, as they also play a significant role in ensuring that lubrication is appropriately administered within the system.

The other options do not align with the primary functions of a manual pressure reducing throttle valve. While increasing pressure is not a purpose of throttle valves, monitoring temperature is a task typically handled by thermometers or temperature sensors, and preventing backflow is generally managed by check valves or specific backflow prevention devices.