In this work, a new model is introduced to determine the crossflow velocity required to dislodge permeating oil droplets at the surface of a membrane. Oil droplets at the surface of a membrane face either of four fates; namely, pinning, permeation, rejection, or breakup. The conditions at which the first three fates are realized have been, to a large extent, satisfactorily explored. The conditions for the breakup, however, do not seem to be very well defined. Although there exist few attempts to define conditions for breakup by crossflow field, they seem insufficient and lack consistency with the physics. It is, therefore, the aim of this work to provide elaborate analysis based on a clear understanding of the physics involved and the forces contributing to the breakup. A mathematical formula is developed to estimate that critical crossflow velocity at which break up occurs. This formula is derived based on the balance of torques that are generated by the interplaying forces. These forces are essentially surface tension forces and drag force. When the droplet encounters a pore opening it forms an interface and if the pressure across the opening is larger than the entry pressure, the interface advances inside the pore. When the receding interface of the droplet reaches the pore opening, the droplet pauses and anchors itself by that portion of the droplet in the pore. The droplet then continues to deform in accordance with the interplay of the imposed drag force and the generated surface force. The droplet wraps around the pore opening and the central angle of encounter increases per the imposed drag force. When the central angle of encounter reaches π radians, this represents the critical configuration beyond which the droplet breaks down to two parts. As the droplet deforms while anchored in its place, the contact line around the pore opening uncover the surface and starts to contribute towards the torque about the pivoting point. The balance of torques generated by the drag force and the interfacial force at that portion of the contact line, which makes a central angle of π radians, is used to determine that critical velocity beyond which the droplet breaks up. Several verification exercises are conducted using computational fluid dynamics (CFD) analysis to build confidence in the derived formula of the critical crossflow velocity. Based on the comparisons, the newly derived formula compares very well with the data obtained using CFD analysis.