A fluid processing assembly can be easily inserted into and removed from a rotatable centrifuge channel. The processing assembly comprises a processing container and a carrier. The processing container has flexibility and, in use, occupies the channel to receive fluids for separation in the centrifugal field. The carrier retains the processing container outside the channel in a flexed condition conforming to the channel. The carrier resists deformation of the processing container during its insertion into or removal from the channel.
