Helium recovery and cleaning for high-pressure gas quenching connected to an atmosphere furnace

High-pressure gas quenching with helium is environmentally-friendly techniq ue which can rival the cooling power of oil quenching. However, the expensi ve gas can be employed economically only if it is recycled, as in systems a vailable for recovering pure helium when used in vacuum furnaces. When the gas is adopted for quenching in combination with an atmosphere furnace, say for gas carburising, the recycled helium must also be cleaned with respect to contaminating gases. This paper describes such a dual-purpose recycling system which has been in operation and tested for several years.