Mechanical shaft seals used on water service...

Question 1 of 270705eccef9bbacbc34ba4d45453

Mechanical shaft seals used on water service pumps require lubrication of the seal faces to minimize deposits of foreign matter on those surfaces. Which of the following pressures and lubricants are required?

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Question 1 of 27070

🔍 Key Concepts

• Mechanical shaft seal cooling and flushing needs on centrifugal and water service pumps • Difference between using water vs. oil as a seal face lubricant in a water pump system • Why a slightly higher (positive) vs. lower (negative) pressure is used for any flushing or sealing medium

💭 Think About

• Think about what medium is already present in a water service pump and which lubricant would be most compatible with that system and its cargo. • Consider whether you want the lubricant to leak into the pump or the pumped liquid to leak into the seal area—how does pressure (positive vs. negative relative to pump casing) affect that? • Ask yourself which arrangement best prevents foreign matter and sediment from getting between the seal faces.

✅ Before You Answer

• Confirm which fluid would avoid contaminating the water system and be readily available for continuous flushing. • Check whether the sealing fluid should be at a pressure slightly higher or lower than the pressure in the pump casing to keep debris away from the seal faces. • Verify that the chosen option would keep a clean film across the seal faces and flush dirt away rather than draw it in.