Dave’s Corner: Dry Running Diaphragm Pumps

All Yamada diaphragms are rated to 100 PSI maximum and in many applications are run at pressures greater than 100 PSI without incurring diaphragm damage. Even though you can run diaphragm pumps dry, it is something that you should avoid for several reasons:

  • Every cycle a pump runs dry is one less cycle it will run to perform work.
  • Running a PTFE diaphragm dry can cause premature failure. We rate it to 100 PSI air pressure if there is liquid in the pumping chambers to help counterbalance the high air pressure.
  • Why pay for compressed air? That is a waste of money.

If using PTFE diaphragms, and there is no liquid present, we recommend limiting air pressure to 70 PSI. To help prevent damage to the PTFE diaphragms you may want to consider a Liquid Level Controller (LLC-1 through LLC-4) or a device to shut the pump off, such as a DRD-100, during dry run times.

Product Update: Aluminum Air Chamber & Diaphragms

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: