Abstract: A plurality of scanning regions (22) are disposed about the anticipated region of a phase boundary (32) of two media. The change in position of the phase boundary (32) is detected by a scanning means (18) with which each scanning region (22) is scanned and a signal is generated for each of the scanning regions (22). The first media is more radiation-permeable than the second media. A beam path is generated by the scanning means and is detected and evaluated by a discriminator circuit as a logic one. The second media is less radiation-permeable than the first media. The absence of a beam path corresponding to scanning regions in the second media is evaluated by the discriminator circuit as a logic zero. The number of signals per measuring cycle is compared against the actual number of scanning regions (22) to locate and control the position of the phase boundary (32).

Abstract: A centrifugal separator for separating two liquid components from each other normally has continuously open outlets for both liquid components, an interface layer formed in the separating chamber between the separated liquid components being maintained at a predetermined radial level. The present invention concerns a special arrangement for continuous discharge of the light liquid component but intermittent discharge of the heavy liquid component. For this purpose, a first outlet channel (20) in the centrifuge rotor for the heavy liquid component communicates through a calibrated opening (24) with a stationary second channel (23) outside the rotor, said second channel comprising a shut off valve (31). An equipment (28) is arranged to indicate when an interface layer formed in the separating chamber (8) of the rotor between the separated liquid components has moved radially inwards to a certain level (29).

Abstract: A system of self-purging centrifugal separators for the separation and clarification of liquids, especially heavy oil, which contain solids, has a first separator serving for preliminary separation and a second, clarifying separator connected to the output of the first. Each of these separators is purged of accumulated solids by means of associated controls, the second separator being additionally provided with an automatic purging control. The solids chamber of the clarifier drum is smaller than that of the drum of the first separator and the purging control communicates through a control line with an evaluator and the evaluator in turn communicates with the controls and/or with an alarm, whereby a premature disturbance due to the accumulation of sludge in the first separator is detected and eliminated by extra purges or is signaled by means of the alarm.

Abstract: An improved method and apparatus are disclosed for sealing the outlet port of a flexible blood-processing bag after a separated first blood component has been expressed therefrom. The improvements relate to the use of a valve contained within the flexible blood-processing bag and responsive to the difference in specific gravities between first blood component and second blood component. For example, the valve may comprise a stopper ball having a specific gravity which allows it to float at the interface between first and second blood component.