A tube for collection, separation and dispensation of a two-phase fluid is provided with a elongated rigid tubular container having a fluid entry end a closable end and a float. The float retained within the tubular container is positioned between the light phase and the heavy phase of the fluid on centrifugation...http://www.google.com.au/patents/US5456885?utm_source=gb-gplus-sharePatent US5456885 - Fluid collection, separation and dispensing tube
