A DEVICE FOR ENABLING A LIQUID TO BE DISCHARGED FROM A ROTATING CHAMBER THROUGH AN END OPENING FORMED IN A CASING PORTION THEREOF AND FOR PREVENTING A GASEOUS FLUID FROM FLOWING THROUGH SAID OPENING IN EITHER DIRECTION, WHICH COMPRISES THE OUTER SEMITORIC HALF OF A TORIC CHANNEL WITH ONE OPENING OF THE CHANNEL DIRECTLY AND SEALINGLY CONNECTED TO SAID CASING END OPENING AND WITH THE CONVEX SURFACE OF THE CHANNEL IN A POSITION RADIALLY MORE REMOTE FROM THE ROTATIONAL AXIS OF THE CHAMBER THAN SAID OPENING, A DISC TRANSVERSE TO THE AXIS EXTENDS RADIALLY INTO THE CHAN-

NEL SO THAT, UPON LIQUID BEING DISCHARGED FROM SAID CASING END OPENING, SAID LIQUID FIRST FILLS SAID CHANNEL TO FORM A LIQUID PLUG BEFORE ISSUING AT THE OTHER END OF THE CHANNEL. IN A PREFERRED EMBODIMENT THE CASING END OPENING AND THE CHANNEL EXTEND, WIDTHWISE, CIRCUMFERENTIALLY AROUND THE ENTIRE CHAMBER.