We present the method of the liquid helium enrichment with He3 isotope based on a special solution of the helium bath cryostat (251 LHe) equipped with the heat exchanger and entropy filter to stimulate quantum filtration process in low temperature region. The cryostat design makes it possible to increase the initial concentration of He3 more than one order of magnitude. While the temperature of lambda point was achieved close to the capillary-equipped heat exchanger, the movement of lambda front within the liquid helium is observed. A consistent description of the various stages of the cryostat operation with cooling process above the lambda transition, during the long period of lambda front movement and in a superfluid region, with the acquisitioning of He3 isotope in all of these regions, is devoted to the design of a helium isotope flow-separator on an industrial scale.