The relationship between the relative critical submergence (Sc/D) determined by the vacuum pressure measurement method and the Froude numbers of P1 and P2 pumps was analyzed. The results are illustrated in (Figure Presented). Purpose: In this study, it is aimed to relate the critical submergence in deep well pumps with Froude, Weber, and Reynolds numbers. Theory and Methods: In this study, the critical submergence of 3" and 4" outlet shaft pumps with three different water inlet cross-sectional areas and five different flow rates were determined by the vacuum measurement method. Relative critical plunging depth and Froude number are compared with the equations of other researchers in the literature. In addition, the vortices formed at very low plunging depths of the pumps were photographed with a camera, and vortex types were determined. Results: In all water inlet diameters of the pumps, critical submergence increased as the flow rate increased. At constant flow rates, the critical submergence decreased as the water inlet diameters increased. It was observed that the submergence at which the vortex occurred were smaller than the critical submergence. This indicates that the vortex occurs at submergence smaller than the critical submergence and the critical submergence is under assurance. An Equation was developed for the Froude number and relative critical submergence of the pumps according to Figure A. The R2 value of this equation is 0.996. As can be seen from Figure A, with the increase in Froude number, the value of the relative critical submergence also increases. In all physical models of P1 and P2 pumps, vortex formation depths vary between 20-70 mm and 20-145 mm, respectively. For the pump types, the vortex formation depth increased with the increase in Froude number. This is because the increase in the entry velocity of water into the pump increases the surface stress. Increasing the inlet area in the P1 pump decreased the Wcr (critical Weber) and Re values. Wcr and Re values were obtained as Wcr>1600 Re>3,1x105, Wcr>1100 Re>2,7x105 and Wcr>750 Re>2,4x105 for D1, D0 and D2 models respectively. Wcr and Re values obtained from P2 pump were determined as Wcr>790 Re>2,9x105, Wcr>500 Re>2,6x105 and Wcr>350 Re>2,3x105 for D1, D0 and D2 models respectively. Conclusion: According to the dimensionless quantities used to determine the critical submergence of deep well pumps, it is appropriate to use the original models (D0 diameter) for both pumps (P1 and P2) analyzed in this study.