What is an effective stop for a gauge?

The effective stop for a gauge is designed to ensure accuracy and prevent damage when the pressure reaches a point where it should no longer operate correctly. The indicating point at zero serves as a crucial reference for calibration and functionality. When a gauge is at zero, it indicates that there is no pressure within the system, which is the baseline or starting point for accurate readings.

This effective stop is essential for proper operation because if a gauge is allowed to go below this point, it may lead to confusion in readings, diminished functionality, or even mechanical failure. The other options do not serve the same purpose; for instance, the maximum pressure reading is relevant for indicating limits, but it does not ensure the gauge's accuracy or safety at lower or baseline levels. The minimum pressure reading may denote operational limits but lacks the foundational role that the zero indicating point provides. Lastly, the needle position at full scale is relevant for understanding maximum capacity but does not address the critical need for accuracy at the lower end of the pressure range. Therefore, the indicating point at zero is the most effective stop for ensuring the accuracy and safety of the gauge's readings.