... valve head), change the distance between disc and seat to control valve shut up.Streamlined cut-off ... valvesracteristics: the gate valves are handwheels, stem and packing in central, threaded, small culvert seal ... pipeline, should be made by the upward through seat, and the so-called "low", into the goal ... higher resistance to flow, open effort and closed stem and packing culvert of contact with the media ...