and or providing lubricant or coolant to the bearings and seals of the pump the two piece housing providing several improvements including the ability to make the two pieces from different materials the reduction in scrap castings due to imprecision achieved in the casting process and improved structures in the housing for monitoring the lubricant chambers in the housing application_number US 201113189408 A description fig1 illustrates a self priming centrifugal pump 10 of the prior art having a single piece construction of the bearing housing 12 self priming pumps are well known in the art and a description of the overall structure of the pump is not required here for the understanding of the present invention the bearing housing 12 is part of the rotating assembly 14 which further comprises the impeller 16 the drive shaft 18 to which the impeller 16 is attached by an impeller bolt 20 a mechanical shaft seal 24 lip seals 26 forward bearing 28 rear bearing 30 and the bearing cap 32 the impeller 16 is spaced from the bearing housing 12 by a seal plate 36 that is secured against the pump casing 38 and which provides a housing for the mechanical shaft seal 24 the mechanical shaft seal 24 surrounds.