Before charging, how should the discharge line be prepared to prevent surging?

• A. Leave the line partially filled with air.
• B. Ensure the line is fully primed and free of air pockets before charging.
• C. Open the discharge valve wide and charge rapidly.
• D. Purge air only after charging begins.

Answer: (B)

Preventing surging comes from having a discharge line that is fully primed and free of air before you apply pressure. Air trapped in the line is compressible, so when the pump starts pushing water, that trapped air compresses and then releases, creating pressure spikes and unstable flow—the surge. By ensuring the line is completely filled with water and all air has been purged, you establish a continuous, solid water column. This allows the pump to build pressure smoothly rather than fighting pockets of air. Practically, use the priming method to push out air and vent the line until water is seen at the discharge end, then charge gradually. Leaving air in the line or charging with air pockets present will lead to surging and potential damage.