🔍 Key Concepts

• Gravity feed lube oil system layout: service pump → overhead (gravity) tank → main lube oil header • Difference between pump discharge pressure and static head pressure from a raised tank • What happens to line friction and pump pressure once the oil is in the gravity tank

💭 Think About

• Draw a simple sketch of the system from the sump to the header, including the service pump and gravity tank. From what point to what point is the main lube oil header actually supplied? • When the gravity tank is full and the pump is secured, what continues to create pressure at the header, and how is that pressure determined? • Think about whether the pump pressure and static head act at the same time on the header, or if one is used mainly to fill/maintain the gravity tank level.

✅ Before You Answer

• Identify where the pressure is measured: at the main lube oil header, not at the pump discharge • Decide if the pump’s job is to continuously pressurize the header or mainly to lift oil into the gravity tank • Remember that static head pressure depends on the height of the oil column above the header, not on the pump’s rated discharge pressure