Abstract: Control system for measuring/detecting transient fluid flow in a positive displacement pump lubrication system using time-differential pressure measurements. A pressure-actuated transducer for a captive oil column in the injection circuit imparts a proportional voltage signal to an electronically differentiating high pass filter, rendering it independent of any base line steady-state component. The resultant signal is fed into a comparator used to discriminate rates of pressure change against a preset reference level, thereby sensing transient spike pressures covering a wide range of adjustable frequencies and pump displacement strokes to thereby confirm required lubrication flow. The same transducer voltage signal transmitted during a steady-state portion of the pump cycle between injections is monitored for high and low set points such as incident to downstream blockage or system leakage.