Robbins & Myers 340-3500-120 Nitrile Stator for Moyno 500 301 Series
This NBR nitrile stator is the elastomer half of the pumping element in the Moyno 500 301 Series models 30100, 30102, 30104 and 30105. Its internal bore is molded as a double helix, and the single helical rotor running inside it forms a line of sealed cavities that march the liquid forward one cavity at a time. That is what gives a Moyno pump its smooth, low shear, nonpulsating flow and its ability to meter at a rate proportional to shaft speed.
A stator is a wear part by design. The rotor is in constant sliding contact with the bore, so over time the interference fit relaxes and liquid begins slipping backwards through the cavities instead of being carried forward. The pump still turns and still primes, but it no longer reaches the pressure it used to and the flow falls away. Matching the elastomer to the liquid matters as much as matching the part number: NBR nitrile is rated for a service range of roughly 10 to 160 F, and a liquid that attacks the compound will swell, soften or harden it long before abrasion would have worn it out. One stator covers every 301 Series model, with EPDM and fluoroelastomer versions supplied under their own numbers.
Key Features
- Genuine Robbins & Myers Moyno replacement stator
- NBR nitrile elastomer construction
- Molded for the Moyno 500 301 Series models 30100, 30102, 30104 and 30105 pumping element
- Restores the rotor to stator interference fit that sets discharge pressure
- Brings flow and pressure back to the original duty point
- Approximate elastomer service range of 10 to 160 F
- Direct replacement with no machining or modification
Applications
- Moyno 500 301 Series models 30100, 30102, 30104 and 30105 progressing cavity pumps
- Restoring flow and discharge pressure that have fallen away gradually
- Rebuilding a pump after a dry running incident
- Changing elastomer compound to suit a different liquid
- Scheduled overhauls on metering and transfer duties
- Industrial, marine, dockside and washdown installations
Specifications
- Brand: Robbins & Myers
- Manufacturer: Robbins & Myers (Moyno)
- Manufacturer Part Number: 340-3500-120
- Part Type: Stator, progressing cavity pumping element
- Material: NBR nitrile
- Elastomer Service Range: approximately 10 to 160 F
- Quantity Used: One per pump
- Fits: Moyno 500 301 Series models 30100, 30102, 30104 and 30105
- Condition: New
Frequently Asked Questions
Q: Does direction of rotation matter?
Yes. These pumps are built to turn one way, and running one backwards puts the discharge pressure on the suction side of the pump. Confirm rotation after any motor rewiring, before the pump is allowed to see liquid.
Q: Should the rotor be replaced at the same time?
If the rotor still has intact plating and no scoring it can be reused. Once the plating has worn through, the exposed base metal is rough enough to chew through a new stator quickly, so at that point the pair should be changed together.
Q: Can the pump be left standing full of liquid between runs?
Liquid sitting in the stator causes no harm. A pump left standing dry for a long period is the greater risk, because the elastomer can take a permanent set against the rotor. Turning the shaft by hand from time to time avoids that.
Q: Can the stator be changed without unbolting the pump from its base?
On the smaller Moyno 500 pumps the suction housing and stator come off the front while the pump stays bolted down, which is quicker than breaking the drive coupling. Leave clear space in front of the pump at least equal to the length of the stator so it can be drawn straight off.
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 stator before you order.
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