🔍 Key Concepts

• Characteristics of positive displacement pumps (like spur gear pumps) • What happens to pressure when flow is restricted on the discharge side • Difference between how you operate a centrifugal pump vs. a gear pump

💭 Think About

• Think about what happens inside a gear pump if the discharge line is restricted and the pump keeps forcing the same volume of liquid forward. • Compare: Is it generally safe or unsafe to "throttle" the discharge of a positive displacement pump? Why? • Which discharge valve position would minimize the risk of overpressure and potential mechanical damage to the pump or piping?

✅ Before You Answer

• Verify whether a spur gear pump delivers nearly constant flow regardless of discharge pressure. • Consider where a relief valve is normally installed on positive displacement pumps and why that matters for valve operation. • Check which valve position would avoid dead-heading or excessive back pressure on a gear pump.