Yamada 771110 Diaphragm, PTFE for NDP-25 and NDP-32
The Yamada 771110 is the genuine replacement PTFE diaphragm specified for NDP-25 and NDP-32 Series pumps including NDP-25BST. Each stroke flexes it from one extreme to the other, and it does this several hundred times a minute at full flow, which is a great deal of work for one piece of molded elastomer.
Material choice is what makes the difference between a diaphragm that lasts and one that does not. PTFE covers the widest chemical range of any diaphragm material and is the usual choice for aggressive product and high purity duty, at the cost of flexing less freely than an elastomer, so it is paired with a backing diaphragm and a matched center rod. Always match the elastomer to the fluid, the temperature and the abrasiveness of what is being pumped rather than simply ordering what came out.
Key Features
- Genuine Yamada replacement diaphragm
- Material: PTFE
- Fits NDP-25 and NDP-32 Series pumps including NDP-25BST
- Two per pump - always replace diaphragms in pairs
- Restores full stroke volume and flow
- Molded to the factory profile for correct flex life
Applications
- NDP-25 and NDP-32 Series pumps including NDP-25BST
- Scheduled diaphragm changes on transfer and dosing duty
- Restoring lost flow and slow cycling
- Repairing a pump venting product from the muffler
- Converting a pump to a different elastomer for a fluid change
- Marine, industrial, chemical and washdown service
Specifications
- Brand: Yamada
- Manufacturer: Yamada America
- Manufacturer Part Number: 771110
- Part Type: Diaphragm
- Material: PTFE
- Fits: NDP-25 and NDP-32 Series pumps including NDP-25BST
- Quantity Used: Two per pump
- Series Port Size: 1 in on the NDP-25 Series
- Condition: New
Frequently Asked Questions
Q: Do I need to change the center disks at the same time?
Inspect them. The disks clamp the diaphragm and any burr, dishing or corrosion on them is transferred straight into the new diaphragm as a stress point, so a marked disk is worth replacing while the pump is open.
Q: Why replace both diaphragms when only one failed?
The second one has seen exactly the same number of cycles and the same fluid, so it is close behind. Beyond that, two diaphragms of different age and stiffness load the center rod unevenly and shorten the life of the new one.
Q: Product is coming out of the muffler. What does that mean?
That is the signature of a split diaphragm. The fluid side has broken through into the air side and is being vented through the exhaust. Stop the pump, because the air motor is now getting product through it and the valve internals will suffer.
Q: Which diaphragm material should I choose?
It depends on the fluid, the temperature and how abrasive the product is. PTFE handles the widest chemical range but flexes less freely, Santoprene and Hytrel give long flex life, Buna-N suits oils and fuels, EPDM suits water and many chemicals, and Viton suits aggressive service.
Not sure this is the right part? Send us a Picture of the Pump Plate on your pump and the CLR Marine team will confirm the correct diaphragm.
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