Yamada 770593 EPDM Check Ball for NDP-40
The Yamada 770593 is a genuine Yamada check ball, EPDM, used in NDP-40 series air-operated double diaphragm (AODD) pumps. It seats against the valve seat on every stroke to force fluid to flow in one direction only. Together the two check balls and their seats are what let a reciprocating diaphragm pump move liquid without a separate mechanical valve.
Genuine Yamada replacement parts are machined and molded to the original factory tolerances, so fit, alignment and seal engagement match the component being replaced. Two per pump (one per chamber). Always compare the exact part number against your pump's nameplate before ordering, since Yamada varies internal components by both pump size and body material / elastomer combination.
Key Features
- Genuine Yamada replacement check ball
- Material: EPDM
- Fits NDP-40 series AODD pumps
- Two per pump (one per chamber)
- Molded or machined to factory tolerances for correct fit and seal engagement
Applications
- NDP-40 series AODD pump service and rebuilds
- Scheduled preventive maintenance
- Restoring lost flow, leaks, or erratic cycling
- Marine, industrial, chemical and wash-down service
Specifications
- Brand: Yamada
- Manufacturer: Yamada America
- Manufacturer Part Number: 770593
- Part Type: Check Ball
- Material: EPDM
- Fits: NDP-40 Series
- Condition: New
Frequently Asked Questions
Q: Can I run the pump a little longer before replacing a worn part?
You can, but a part that has started to degrade wears the components around it faster, so a delayed replacement often turns a small parts order into a larger rebuild.
Q: Should I replace just this one part or the matching set?
Replace the matching set (both check balls, both diaphragms, or all the seats/gaskets disturbed in the rebuild) at the same time. Parts that run the same duty cycle wear together, and replacing only the failed one is the most common reason a rebuild needs redoing soon after.
Q: What is the earliest sign this part is wearing out?
Reduced flow, slower cycling, or - for diaphragms and check valve components specifically - fluid appearing at the air exhaust muffler, which signals a breach between the wet side and the air side.
Q: What causes this kind of wear part to fail?
Flex fatigue from normal cycling, chemical attack from the pumped fluid, or heat and hardening over time. Whichever it is, the fix is the same: replace it, and note which failure mode it was so the replacement material can be matched to the service.
Not sure this is the right part? Send us a picture of your Pump Plate to https://www.clrmarine.com/Contact-Us and the CLR Marine team will confirm the correct check ball.
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