Genuine Yamada 770636 Viton (FKM) check ball for NDP-50 series air-operated double diaphragm (AODD) pumps.
Check balls work with the valve seats as one-way valves: each ball seats to block backflow, then lifts to let fluid through as the diaphragms cycle. Worn, swollen, or out-of-round balls cause lost prime, reduced flow, and erratic stroking — replacing them restores consistent pumping.
Material: Viton is a premium fluoroelastomer offering broad resistance to fuels, oils, solvents, and many aggressive chemicals, plus higher temperature tolerance.
- Fits: Yamada NDP-50 series AODD pumps built with Viton ("V") elastomers
- Quantity: NDP-50 pumps use two of these balls per Yamada's parts list — order two for a complete valve rebuild
- MPN: 770636 | Brand: Yamada America
Your Yamada model number ends in a letter that identifies the elastomer (C = Neoprene, N = Buna-N, E = EPDM, V = Viton, T = PTFE). Match that letter before ordering, and check a chemical compatibility chart for your specific fluid.
Not sure it's the right part? Send us your exact Yamada model number before you order and CLR Marine's team will confirm fit — we're a veteran-owned marine parts supplier and would rather you get the right part the first time.
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