This kind of pump adopt double-suction structure, both ends of screw are in the same of pressure cavity, axial force can be balanced automatically. The bearing of both ends adopt external installing, and being lubricated alone by using lubricate, so it won't be influenced by the medium. A couple of synchronous gears are used to drive the screws, so the screw surface can't touch at all, and there is a tiny clearance between the two screws. The impurity in the medium can not fray the screw surface directly ( except scour). Except some less discharge pumps ( below the 2w.w 4.0 )generally, internal safety valve will be installed on the pump body, when the discharge pressure is over the rated they would protect the function.there are two entrance - exit directions, one is horizontally enter and horizontally exit; the other is horizontally enter and vertically upwards exit; the user can choose according to their own demands.