Certifications & Patents European CE Mark Granted by NCEE Labs May 4, 2020. U.S. PATENTS granted to HVLPO2, LLC dba High Volume Oxygen for Method and Apparatus for Managing Oxygen Generating System 8,702,840 granted April 22, 20148,876,941 granted November 4, 20149,139,434 granted September 22, 20159,372,488 granted June 21, 201610,073,441 granted September 11, 2018 Share this:TwitterFacebookLike this:Like Loading...