Robbins & Myers 320-6501-000 Fluoroelastomer Seal for Moyno 331 to 344
Part number 320-6501-000 is the genuine Moyno rotary seal in FKM fluoroelastomer with carbon and ceramic faces for the Moyno 500 Models 331, 332, 333 and 344. It is the barrier between the wet end and everything behind it, and it is the component that decides whether a pump drips or stays dry.
The seal is normally renewed whenever the wet end is opened, because it is inexpensive next to the labor of reaching it and because a used seal rarely beds down properly a second time. This one is sized for a 0.625 in shaft. Check the shaft itself while the seal is out: a groove worn where the old seal ran will cause the new one to leak however carefully it is fitted. FKM fluoroelastomer with carbon and ceramic faces gives an approximate service range of 10 to 240 F. It is the fluoroelastomer seal supplied in the FPM conversion kits for the whole 331 to 344 range, where nitrile would not suit the liquid.
Key Features
- Genuine Robbins & Myers Moyno replacement rotary seal
- FKM fluoroelastomer with carbon and ceramic faces elastomer
- Sized for a 0.625 in shaft
- Lapped face design lubricated by the pumped liquid
- Keeps pumped liquid away from the bearings and drive end
- Approximate elastomer service range of 10 to 240 F
- Direct replacement with no modification required
Applications
- Moyno 500 Models 331, 332, 333 and 344 progressing cavity pumps
- Curing a leak or weep at the shaft where it leaves the pump body
- Routine renewal whenever the wet end is opened
- Rebuilding a pump after a dry running incident
- Changing elastomer compound to suit a different liquid
- Industrial, marine, dockside and washdown installations
Specifications
- Brand: Robbins & Myers
- Manufacturer: Robbins & Myers (Moyno)
- Manufacturer Part Number: 320-6501-000
- Part Type: Rotary seal, shaft
- Material: FKM fluoroelastomer with carbon and ceramic faces
- Shaft Size: 0.625 in
- Elastomer Service Range: approximately 10 to 240 F
- Quantity Used: One per pump
- Fits: Moyno 500 Models 331, 332, 333 and 344
- Condition: New
Frequently Asked Questions
Q: Can the pump be run briefly without liquid to check rotation?
A few seconds to confirm direction does little harm, but anything longer runs the faces dry and heat checks them. If a longer test is needed, flood the wet end with a compatible liquid first.
Q: What else is worth replacing at the same time?
The shaft slinger and any joint boot nearby, since both are reached on the same strip down and both fail quietly. If the leak went unnoticed for a while, check the bearings for roughness as well.
Q: Does the elastomer compound change how the seal is fitted?
No, the fitting procedure is the same. The compound governs which liquids and temperatures the seal tolerates, which is why the same seal is offered in more than one material under separate part numbers.
Q: The shaft has a visible groove. Can the seal still be used?
Not reliably. A new seal running in an old groove will leak, because the faces cannot follow the step. The shaft needs replacing, or in some builds a shaft sleeve or a repositioned seal is the accepted fix.
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 rotary seal before you order.
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