oil leakage connector 30 is provided on the other part for attachment to vaccuum pump 33 via connecting means 32 which may be a vacuum hose and or piping at numeral 31 is located a vacuum gauge connector for connection with a vacuum gauge which ensures that a vacuum is being pulled in the enclosed area when vacuum pump 33 is operational closing brackets 27 and bolts 28 provide the means for maintaining the two housing 24 parts in the closed position around the screw shaft housing in fluid tight relationship therewith to enclose the area of air leakage the materials of construction are preferably as follows for the gaskets a synthetic rubber such as neoprene or viton trademark of e i dupont de nemours company for several fluoroelastomers for clamping rings 21 a hard metal such as carbon steel for window 29 a plexiglas sheet trademark of rohm amp haas company for a thermoplastic poly methyl methacrylate type polymer in cast sheet for the screws carbon steel or stainless steel and for the other elements a metal such as stainless steel or aluminum it is considered within the scope of this invention to provide a non hinged housing as the enclosure which may be mounted in some other fashion enclosure 20 is placed in operation as follows housing parts 24 and clamping rings 21 are pivoted into their open positions and placed adjacent the screw shaft housing with one clamping ring 21 above the cut away access to bolts 18 and the other clamping ring 21 therebelow the clamping rings 21 are moved to their closed position and locked via locking guides 22 and bolts 23 housing parts 24 are then pivoted to the closed position and housing 24 is closed around the screw shaft housing in fluid tight.