How does a pressurized reservoir affect recommendations for inlet conditions?
The specific case in question is lubricating oil for a screw compressor, drawn from a gas-oil separator (ie. pressurized reservoir). The gas-oil separator operates at 130 psi, and the pump increases this by a further 35 psi.
Looking at the Hydraulic Specialist Study Manual Outcome 3.3.2, it seems to me that cavitation from pulling a vacuum is very unlikely to happen at operating conditions (although start up from an unpressurized reservoir is still a concern). Therefore the inlet velocity maximum (1.2 m/s) can be relaxed and the inclusion of a suction strainer is less of a concern.
Would aeration also be less of a concern due to the high tank pressure and low pressure rise over the pump? Aeration is managed by oil retention time, but is it also affected by surface area of the gas-oil interface? That is, given the same amount of oil, would a wide tank be more effective at reducing aeration at the pump than a tall tank?
Looking at the Hydraulic Specialist Study Manual Outcome 3.5.2, cylindrical and centrifugal reservoirs are suggested to improve the removal of gas from the oil. How can the efficacy of these options be judged? Is CFD analysis required?
The specific case in question is lubricating oil for a screw compressor, drawn from a gas-oil separator (ie. pressurized reservoir). The gas-oil separator operates at 130 psi, and the pump increases this by a further 35 psi.
Looking at the Hydraulic Specialist Study Manual Outcome 3.3.2, it seems to me that cavitation from pulling a vacuum is very unlikely to happen at operating conditions (although start up from an unpressurized reservoir is still a concern). Therefore the inlet velocity maximum (1.2 m/s) can be relaxed and the inclusion of a suction strainer is less of a concern.
Would aeration also be less of a concern due to the high tank pressure and low pressure rise over the pump? Aeration is managed by oil retention time, but is it also affected by surface area of the gas-oil interface? That is, given the same amount of oil, would a wide tank be more effective at reducing aeration at the pump than a tall tank?
Looking at the Hydraulic Specialist Study Manual Outcome 3.5.2, cylindrical and centrifugal reservoirs are suggested to improve the removal of gas from the oil. How can the efficacy of these options be judged? Is CFD analysis required?