Abstract: In order to eliminate bubbles in a liquid, the liquid is introduced into a flow passage having circular cross section as tangential flow which turns into swirl flow circulating around axis along the shape of the flow passage and that accelerates and decreases the pressure of the swirl axis and collects bubbles at the portion where pressure becomes lowest, and discharges the collected bubbles through a vent hole or a small vent pipe.

Abstract: A liquid is introduced tangentially into a cylindrical body through a plurality of equiangularly spaced inlet ports disposed on the cylindrical body adjacent to a closed end thereof. Thus, the liquid is swirled in the cylindrical body and bubbles in the liquid are collected, by means of the centrifugal force in the swirl flow, toward the axis of the cylindrical body at the inflow side and are removed.

Abstract: In order to prevent bubbles collected by a bubble collecting device from flowing again into a fluid, the bubbles are positively discharged from a bubble collecting zone and directed to an upper portion in a liquid container so that even when the fluid is discharged together with the bubbles, such discharged fluid is positively recovered in the fluid vessel.

Abstract: Disclosed is a method for causing bubbles in a fluid to coalesce into a coherent mass by use of a vessel having a cylindrical space therein wherein the fluid is caused to flow into the vessel at such a velocity that a vortex is generated to flow from one end of the space to the other while establishing a state in which the pressure on the center axis of the cylinder rises from one end toward the other, then reaches a maximal value and thereafter drops, and this coalescing of the bubbles is effected at the field near the axis of the vortex and between a position close to the inflow position and the position of the highest pressure. The method greatly facilitates deaeration.

Abstract: A tank for storing a liquid is provided with a circulation passage for circulating the liquid by a suction pump. A pressure at the suction port of the suction pump is maintained at a negative pressure lower than a pressure at which gases dissolved in the liquid and the liquid is circulated, whereby the gases having been dissolved in the liquid are separated and the bubbles entrained by the liquid grow in size. These gases and bubbles are collected, agglomerated and discharged in the line connected to the discharge port of the suction pump.

Abstract: A centrifugal separator for separating gas bubbles from a liquid incorporates a spiral liquid passage with inlet and outlet ends as defined by a top plate, a bottom plate and a strip spirally coiled between the plates and otherwise constructed so that by utilizing the low specific gravity of the bubbles and centrifugal force acting thereon, the bubbles are directed into a bubble trapping compartment for removal.

Abstract: A gas-liquid separator wherein a helical passageway is defined between an outer cylinder and an inner cylinder in such a way that a working fluid with entrained bubbles may be forced to flow tangentially into the helical passage and swirl therethrough. The entrained bubbles are separated from the liquid through centrifugal force produced by the swirling or vortical flow through the helical passageway and trapped or collected inside the inner cylinder, from which they are discharged to the exterior.