A light liquid separator has a removable flow-modifying insert in the form of a coalescence element arranged transverse to the flow direction, the novelty being that the insert (4) consists of coalescence material (e.g. woven fabric) which is positioned in a support frame and which is retained by a liquid permeable and flexible sheath. Preferably, the sheath consists of a net or hose of plastic or wire netting fixed at a few points to the support structure.
