A device for separating low density materials such as gas bubbles from a liquid is disclosed which comprises a chamber defined by an inner wall which in turn defines generally circular, transverse cross-sections about a longitudinal axis. The liquid inlet port extends through the inner wall in a position to pass liquid into the chambers circumferentially about the inner wall for swirling flow within the chamber. Accordingly, lower density components of the fluid, such as bubbles, migrate away from the inner wall toward the center of the swirling flow. An outlet port extends through the inner wall, and is spaced from the inlet port, to collect fluid which is free from the low density materials.