Yamada NDP-25 Series Air Operated Double Diaphragm Pump

46.2gpm, 1in NPT or ANSI Flange intake/discharge ports, available in aluminum, 316 stainless steel, cast iron, Kynar, or polypropylene construction.

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Yamada NDP-20/25/30 Series Air Operated Double Diaphragm Pump Maintenance Manual Yamada NDP-20/25 Series PP/PN Air Operated Double Diaphragm Pump Maintenance Manual
Product Specs
Highlights...

Features

  • 46.2gpm max flow rate
  • 1in NPT Intake and discharge connection
    • 1in ANSI flange available on Polypropylene and Kynar pumps
  • 18ft max dry suction lift
  • 210 max cycles per minute
  • 1/8in (3mm) max solids size
  • 20 to 100psi air supply pressure
  • Air ports:
    • 3/8in Female NPT Air inlet
    • 3/4in Female NPT Air exhaust

The Yamada NDP-25 Series Air-Operated Double Diaphragm Pump is engineered for reliable, maintenance-friendly fluid transfer. Designed with a completely non-lubricated main air valve and independent pilot valve mechanisms, the NDP-25 delivers consistent pump performance. The pump is available in multiple body material configurations, including aluminum, 316 stainless steel, cast iron, Kynar, and polypropylene, providing compatibility with a wide range of fluids.

During operation, compressed air enters the NDP-25 pump and is routed through the main air valve to either diaphragm chamber based on the position of the c-spool air distribution system. Air pressure applied to one diaphragm forces fluid through the discharge ball valve while simultaneously loading the opposing inlet ball valve. At the same time, the connected diaphragm on the opposite side retracts inward, creating suction and drawing fluid into the pump chamber.

At the completion of each full stroke, the diaphragm assembly actuates the pilot valve mechanism, opening an exhaust port and releasing compressed air from the rear side of the main air valve. The resulting pressure differential shifts the main air valve, automatically reversing airflow direction and initiating the next pumping cycle. This reciprocating air valve design enables smooth, stall-resistant operation and reliable fluid handling across demanding industrial pumping applications.