What is the difference between a positive-pressure priming system and a negative-pressure priming system?

• A. Positive-pressure priming uses vacuum to pull water into the pump; negative-pressure priming uses pressurized air to push water into the pump.
• B. Positive-pressure priming uses pressurized air to push water into the pump; negative-pressure priming uses vacuum to draw water into the pump.
• C. Both systems rely on manual hand suction only.
• D. Priming type has no impact on water entry into the pump.

Answer: (B)

Priming a pump relies on getting water into the suction so the pump can create flow. In a positive-pressure priming system, you apply pressurized air to a priming reservoir. That air pressure pushes water from the reservoir into the pump, filling the suction line and displacing any air ahead of it. In a negative-pressure priming system, you create a vacuum in the pump and suction line, and atmospheric pressure then pushes water up from the source into the pump until the suction path is filled. This is why the correct description is that positive-pressure priming uses pressurized air to push water into the pump, while negative-pressure priming uses vacuum to draw water into the pump. The other options don’t fit because priming isn’t limited to manual hand suction in all systems, and the method of priming directly affects how water enters the pump.