5. What type of gas purity to use with the Sensys Evo? Jerome Palamara July 31, 2018 14:43 Updated Follow We recommend a minimum purity of 99.995% for conventional gases Helium, Argon, Nitrogen, Air. Related articles 14. Why the column of the Sensys Evo goes back more? Comments 0 comments Please sign in to leave a comment.