For a pump that produces a negative pressure in a pump casing, a shaft seal system comprises a positive flow of air into the seal system to flow about shaft seals to counteract the negative pressure otherwise being communicated thereto from within the pump casing. The seals engage the rotating shaft and a lubrication passageway supplies lubricant to the shaft seals engaging the rotating shaft, which is driving the rotor. Preferably, no air flows through the seal system when the rotor shaft is stationary and a small air flow, e.g., 0.3 c.f.m. to 1 c.f.m., flows through the shaft seal when the shaft is rotating. This flow rate is preferably monitored.