scope:

Description of Driving Event:

Before starting up vacuum pumps to lower the pressure in an altitude tank, the reservoirs of the pumps were checked for proper oil level. The levels were found to be low and about 5 to 7 gallons of oil were added to the reservoirs of each pump. The pumps were then turned on to start pumping against their isolation valves. When the valves were opened to the tank to allow high gas flow to the pump inlet, oil was discharged through the vent system to the roof of the building. Because of the pressure build up, an elbow in the vent line separated and spilled oil on the pump room roof and the parking lot next to the building.

The investigating committee determined that a false reading was obtained when the oil levels of the pumps were checked prior to starting them up. The missing oil was in the inlet cavities of the pumps and not in the reservoirs where the oil level is measured. When the pumps were started, the excess oil was forced from the inlet cavities to the pump reservoirs, thereby overfilling them.