In the early months of 2008 the aluminum air chamber for the NDP-20 and NDP-25 series pump was modified with a groove in order to accommodate the newly designed diaphragms from Yamada. As a reminder the new air chambers will be marked on the outside of the casting with a “G” in order to make it easier to identify.
The starting serial numbers for both size series are: NDP-20/25 B/A/S – 487505
The Buna, Neoprene, EPDM, and Viton diaphragms will have the new design with the integrated lip. PTFE, Hytrel, and Santoprene wills till use the old design but will be used in conjunction with the following o-ring: