What is the determining factor in whether or not leakage in

What is the determining factor in whether or not leakage in a valve can be internally or externally drained?

Solution

>> Dtermining factor is OEM, Original Equipment Manufacturer

The vast majority of hydraulic systems in operation today have leaks - leaks that are planned. They are designed with a specific function in mind, and in many cases, are documented by the original equipment manufacturer (OEM) as the amount of acceptable leakage under normal operating conditions. Internal planned leakage is typically small orifices or pathways that allow a fluid from a higher pressurized zone of a system to travel into a lower pressurized zone to lubricate, clean and cool a specific component or area. These planned internal leaks do not allow the fluid to exit the hydraulic circuit, so there is no visual indication of its presence. The most common cause of excessive internal leakage is wear of component surfaces during normal operation. Leakage can also result from poor system design, incorrect component selection, poor quality control tolerances during the manufacturing of a component, and incorrect overhaul of rebuilt components. System performance, reliability and increased operating temperatures are the first visual signs of excessive internal leakage.