Progressive cavity pumps are unreliable and can often run dry and fill with excessive grit.

• A. True
• B. Not necessarily
• C. False
• D. Cannot be determined

Answer: (C)

Progressive cavity pumps are positive‑displacement machines that provide a steady flow even with thick sludges and some solids. They are generally reliable when operated within their design limits and with proper maintenance. Running dry is not normal and can quickly damage the pump because the elastomer stator and seals rely on the pumped liquid for lubrication and cooling. They can handle grit to a degree, but excessive grit accelerates wear on the stator and rotor, shortening life; this is why pre-screening and regular wear-part checks are important. So, the claim that these pumps are unreliable and often run dry with too much grit isn’t accurate—the pumps are reliable when used and maintained correctly, and grit management is part of normal operation.