For how long must the pumping system sustain the vacuum once established?

• A. At least 2 minutes
• B. At least 10 minutes
• C. At least 5 minutes
• D. At least 1 minute

Answer: (C)

When testing a pumping system, you need to verify that the priming vacuum can be established and then held reliably. Requiring the vacuum to be sustained for at least five minutes after it’s established checks for leaks in the suction line, primer, or seals and confirms the system can maintain prime under normal conditions. If the vacuum decays during that interval, it indicates a leak or faulty component that would cause the pump to lose prime when drawing water. Shorter hold times might not reveal slow leaks, while a longer hold time isn’t required by standard practice. So the five-minute duration best ensures readiness and reliability of the priming system.