What should the vacuum reading be on a normal self-contained dispenser pump installation?

In a normal self-contained dispenser pump installation, a vacuum reading of 4-6 inches indicates optimal performance for the system. This range signifies that the system is effectively creating the necessary suction to draw fuel from the tank through the lines and into the dispenser without excessive resistance or leaks.

Maintaining a vacuum within this range ensures that the dispenser operates efficiently, minimizing the risk of cavitation, which can occur if the vacuum is too low, or excessive wear on the pump components due to additional effort required to maintain proper flow at a lower vacuum level.

The other ranges provided do not align with the expected operational parameters for such systems; readings outside of this standard range could indicate issues in the system such as blockages, leaks, or wear in the pump equipment, which can ultimately affect fuel delivery and operational reliability. Thus, adherence to the specified vacuum range is critical for ensuring that the dispenser functions as intended and provides proper service without unnecessary complications.