How to tell if your MVE tank is still under warranty.
For MVE tanks serial numbers can tell you when your tank was made.  The warranty expires 3 years for vapor and 5 years from wet tanks from the date made.  All newer tanks start with NPB, If it does not start with NPB then the tank is very old and will not be under warranty.  Next 4 digits is the year.  Next 2 digits is the week.  The last 4 digits is the order the tanks were made  and the last letter references the kind of tank it is.
E.g. NBB2022010810S
NPB = A constant. The manufacturers location 2022 = The year of manufacture 01 - The week of manufacture 0810 - The # of the tank in lineup for the week XC20S - The tank model