Abstract: A positive displacement rotary axial screw pump which comprises a series of sealed closures formed by meshing of the rotors for building the internal pressure gradient of the pump from the pump inlet to its outlet. A programmable logic circuit is provided for signaling impending abnormal pressure conditions in the pump and, upon the onset of such conditions, modifying pump operation to compensate for the abnormal conditions. A pressure monitoring device detects selected disruption in the normal pressure gradient of the pump indicative of the impending abnormal conditions and signals the logic circuit of the impending conditions. The pressure monitoring device includes a pressure sensing device associated with at least one isolated volume for sensing internal pressure gradients of the pump.