Displacement: Calculated based on the number of liters discharged per minute, it is related to the diameter of the hole and the required speed of the flushing fluid from the bottom of the hole, that is, the larger the hole diameter, the larger the required displacement. The up-and-back speed of the flushing fluid is required to be able to flush the cuttings and rock dust cut by the drill bit away from the bottom of the hole in time and be carried to the surface reliably. In geological core drilling, the upward and backward speed is generally about 0.4~1.0 m/min. Pressure: The pressure of the pump depends on the depth of the borehole, the resistance of the channel through which the flushing fluid passes, and the nature of the flushing fluid delivered. The deeper the borehole, the greater the pipeline resistance and the higher the pressure required.