For pre-inlet cooling the housing is equipped with an additional third socket on the suction side. The lube oil supply is effected by splash oil lubrication. The conveying chamber is sealed vacuum-tightly by a sealing system. The driving shaft is sealed by double radial seal rings with grease barrier. Direction of flow vertical from top to bottom. Drive can be effected via a direct coupling or optionally via narrow V-belt (at limited differential pressure).