A pair of long jaws moveable with respect to one another whether mounted in a desk mounted sealer or hand held sealer, compresses, heats and welds liquid filled blood bag or liquid filled tubing placed therebetween. The long jaws also serve as the plates of a variable capacitor of an RF resonant circuit. The flow of RF energy across the pair of jaws, which energy heats the blood bag or tubing and, in conjunction with mechanical pressure, focused RF energy, makes the leak free weld. The sealer welds blood bag and tubing in compartments for handling (cord) blood fractionation, carried out efficiently, conveniently and with minimum danger of contamination of the collected (cord) blood or any fractionated portion or component part thereof.