When pumping from draft which of the following conditions affects a pump's ability?

• A. Water temperature
• B. Air pressure
• C. Barometric pressure
• D. All of the above

Answer: (D)

Drafting relies on atmospheric pressure pushing on the water surface to create the suction that lifts water into the pump. The more lift you need, the more the external conditions matter, especially as the suction approaches the water’s vapor pressure.

Water temperature matters because warmer water has higher vapor pressure. If the suction pressure falls toward that vapor pressure, cavitation can occur, reducing or losing the pump’s prime and its ability to lift water effectively.

Air pressure and barometric pressure are the external pressures that provide the suction head. Lower ambient pressure means less suction head is available, making it harder to draft water from a source, especially if the lift is significant.

Since each of these factors can limit how much lift the pump can achieve and influence cavitation risk, they all affect a pump’s ability to draft. All of the above.