Two experimental apparatus have been built in our laboratory to study He I Two Phase Flow at atmospheric pressure. The first apparatus has been designed to create horizontal flows in a 0.01 m diameter tube. A 0.1 m long visualization has been realised to study flow patterns. Two types of heat transfer coefficient measurement cells have been developed (copper or stainless steel). Some typical results are shown. The second apparatus (under test) is designed to realise vertical flows in 0.01 to 0.014 m diameter tube. For flow patterns study, visualization is possible up to 0.9 m on a upward flow.