Navy Vacuum Pump Replacement with Improvements

Bascom Hunter conducted baseline testing, application analysis, engineering investigation, identification of specific areas of possible design improvement and developed the initial design parameters of the replacement pump during Phase I of this program.Bascom will use the parameters developed during Phase I to design and build a replacement vacuum pump specifically to meet the environmental and operational conditions required for the Navy’s Sub-Surface Ballistic Nuclear Fleet’s Advanced Carbon Dioxide Removal Unit. The vacuum pump assembly design consists of an electric 400Hz AC drive motor, an oil lubricated triple-vane style vacuum pump section and an oil sump with integral air/ oil separator system, oil pump(s), oil filter, oil level sight glass and oil fill/ drain components. The assembly can be mounted on a base plate with interface elements specific to the application, as desired. Compared to the original vacuum pump, Bascom Hunter’s vacuum pump will address the two areas of demonstrated concern; oil temperature and operation at orientations other than horizontal. Appropriate oil temperature control may involve increasing the oil capacity, adding an oil cooler and a deaeration system. An increase in oil capacity will inherently reduce temperatures with an anticipated benefit of extending the service intervals and assist with meeting the requirements for motion/ orientation during operation. The air/ oil separation may be managed with centrifugal and filtration type components. Oil capacity requirements will be established to allow the pump to operate at maximum performance at the minimum oil level, including a margin of safety. Requirements for vacuum pump operation at specified orientations may involve design elements such as baffles, a surge matrix, check valves and a dry-sump oil system. Oil system baffles, a surge matrix and/ or check valves will slow the movement of the oil away from the oil pump pick up point during oscillating attitude changes. A dry sump oil system design utilizes a two-stage pump system and provides increased reliability from its consistent oil supply. The first-stage involves a pressure pump which receives an uninhibited oil supply from the base of a primary oil sump designed with a specific depth/ cross-sectional area ratio and integral baffling. This pump supplies oil, under pressure, to a filter and cooler before distributing it to the rotating assemblies. The second-stage pump is a scavenge pump which collects oil from a small (dry) sump, after the oil has provided lubrication to rotating parts, and returns this oil to the top of the primary oil sump at a tangential angle to assist with deaeration. Additionally, the primary oil sump design allows air to naturally migrate to the top. Another benefit of this type of oil system is the reduction in viscous drag (oil resistance due to excess residual oil within the rotating assemblies).