Purification of recovered helium with low level of impurities: evaluation of two different methods

Helium gas coming from low temperature experimental systems is recovered to avoid losses of this scarce gas on Earth. Once this helium gas has been recovered and before its liquefaction, the impurities contained should be removed. It is possible to achieve a low level of impurities by using the proper materials and procedures on the road to helium recovery. A comparison of two different methods applied for the purification of recovered helium with low level of impurities is reported in this paper. One method is the use of liquid nitrogen traps and the other one is the application of a purification system based on getter materials. The cleaning efficiency has been probed experimentally for both methods through the analysis of the purified He gas. The evaluation covers the life time between regenerations, the everyday care as well as the long term, the energy consumption, the initial investment besides the cost of maintenance of both methods