Air valve technology
Air valve technology is the heart of the air-powered double diaphragm pump and determines reliability. Yamada holds three patents on its field proven valve and enjoys a superior reputation throughout the industry.

Unified Air Valve Concept
To simplify, Yamada offers two common size air valves assemblies within five sizes of pumps further reducing reassembly confusion and parts inventory. They try to unify to reduce multiple air valve designs and revisions. Whether your pumps are functioning continuously or intermittently; at high or low pressure; using dirty or clean air; Yamada offers one field proven design.
Truly Non-Lubricated Air Valve
The patented air valve on all NDP series pumps never requires lubrication or pre-packing. The advanced design eliminates the need for external lubrication which can lead to pumpage contamination and maintenance headaches. Yamada is proud to be the originator of non-lubricated air valve technology for air-powered double diaphragm pumps.
Component Replaceable
All Yamada air valves can be restored with individual components, without requiring complete valve and housing replacement.
Non-Stalling
A patented non-centering, spring-assisted shifter is incorporated into every NDP Series pump, ensuring a positive shift every time.
Ten Features of a Yamada Diaphragm Pump

- Handles a wide variety of fluids with high solids content: No close fitting or rotating parts so liquid with high solids content and/or size can be easily pumped.
- Self Priming: The Yamada pump design (incorporating check valves) allows for high suction lift even at dry start-up and with heavier fluids.
- Ability to run dry: No close fittings or sliding parts are at risk - the pump can run dry without damage.
- Variable flow rate and discharge pressure: Yamada pumps will run at any setting within their operating range simply by adjusting the air inlet pressure and system conditions. One pump can fit a broad spectrum of applications.
- Portable/Simple Installation: Yamada pumps transport easily to the application site. Simply connect your air supply line and liquid lines; the pump is ready to perform. There are no complex controls to install and operate.
- Dead Head: Because the discharge pressure can never exceed air inlet pressure, the discharge line can be closed with no damage or wear. The pump will simply slow down or stop.
- Shear sensitive: The gentle nature and minimal parts contact with the liquid makes Yamada pumps an excellent choice for shear sensitive fluids.
- Explosion Proof: Yamada pumps are operated by compressed air, therefore, they are intrinsically safe.
- Submersible: If external components are compatible - Yamada pumps can be submerged in the liquid by simply running the exhaust line above the liquid level.
- Pumping efficiency remains constant: There are no rotors, gears, or pistons, which wear over time and lead to the gradual decline in performance/flow rate.