The most common priming inhibitor in drafting operations is an ______.

• A. Air leak
• B. Air lock
• C. Debris
• D. Water entry

Answer: (A)

In drafting operations, keeping a continuous column of water in the suction line is essential to establish and maintain the pump’s prime. Small air leaks in the suction line or at the pump seals are the most common enemy because they allow air to be drawn into the line as the pump creates suction. Air is compressible and does not transmit the suction effectively, so the water column breaks and the pump loses prime. Even a minor leak at joints, fittings, or packing can introduce enough air to collapse the liquid column, stopping flow.

Debris can clog the line and hinder flow, but it doesn’t typically cause the immediate loss of prime during initial priming. Air lock describes a condition where trapped air prevents flow after priming, which is related but not the frequent initial inhibitor. Water entry isn’t a problem for priming—having water in the line is necessary, and leaks are what prevent or ruin the prime.