Allweiler SNBA80 ER42 U9W1 Triple Screw Pump

Allweiler SNBA80 ER42 U9W1 Triple Screw Pump

The Allweiler SNBA80 ER42 U9W1 (MPN: SNBA80ER42U9W1) is a high-precision, self-priming, positive displacement three-screw pump engineered for critical fluid-handling applications across maritime and heavy industrial operations. Featuring a hardened and ground drive spindle interfacing hydrodynamically with two secondary idle screws inside a replaceable casing liner, this unit delivers continuous, virtually pulsation-free axial flow.

The pump balances axial hydraulic thrust hydrostatically, eliminating internal mechanical gear contact and minimizing parasitic power consumption. The internal balance line relieves the mechanical seal chamber directly into the suction port, guaranteeing that the mechanical shaft seal experiences only low suction pressure regardless of total system discharge head.

Part Number Cross-References

• Manufacturer Part Number (MPN): SNBA80ER42U9W1
• Equivalent Configurations: SNBA 80 ER42 U9.W1 / SNH80 ER42 / SNA80 ER42
• CIRCOR / Colfax Ref ID: 142-SNBA-80-42-U9-W1

Key Features

1. Pulsation-Free Axial Conveyance: Engineered continuous liquid chambers displace fluids smoothly without shear stress, mechanical churning, or foaming.
2. Hydrostatic Axial Thrust Balancing: Opposing fluid chambers counteract dynamic axial loads, reducing drive friction and maximizing mechanical life of internal parts.
3. Depressurized Seal Chamber: Built-in internal return channel equalizes seal face cavity to inlet suction pressure, preventing mechanical seal blowouts during backpressure spikes.
4. High Suction Lift Capability: Self-priming geometry provides low NPSH (Net Positive Suction Head) requirements, operating reliably under negative suction conditions.
5. Replaceable Insert Assembly: Maintenance downtime is minimized via a replaceable hydraulic cartridge/insert sleeve without requiring total replacement of the outer cast iron body.

Applications

• Marine main engine (2-stroke / 4-stroke) lubricating oil circulation.
• Diesel generator fuel booster, feeder, and fuel conditioning modules (MGO, LSMGO, MDO).
• Heavy fuel oil (HFO) transfer systems and burner feed skids.
• Marine and offshore stern tube, reduction gearbox, and CPP (controllable pitch propeller) lubrication systems.
• Industrial hydraulic loops, turbine lubrication consoles, and steel plant fluid circuits.

Compatibility

• Marine Engines: MAN Energy Solutions, WinGD (Wärtsilä / Sulzer), Yanmar, Daihatsu, Caterpillar MaK.
• Separation & Fuel Modules: Alfa Laval (FCM modules), GEA Westfalia, Auramarine booster units.
• Reduction Gearboxes: Renk, Reintjes, Flender, ZF Marine.

Frequently Asked Questions

Can this pump handle low-sulfur marine gas oil (LSMGO)?

Yes, provided the viscosity remains at or above 3.0 mm/s at operating temperature. For ultra-low viscosity fuels a cooler must be integrated into the fuel supply system, or spindle clearances must be matched to mitigate internal slip.

What is the distinction between bearing design ‘U’ and ‘D’?

The ‘U’ version utilizes an internal ball bearing submerged in and lubricated by the pumped medium. This configuration requires the fluid to be clean and have inherent lubricating properties. The ‘D’ bearing arrangement uses an external, grease-packed bearing isolated from the fluid path, making it suitable for non-lubricating, chemical, or higher-temperature applications.

Why is pressure dropping during hot engine operation?

Pressure drop under elevated temperature is typically caused by oil viscosity thinning below design specifications or wear on the balance bushes and spindle screw edges. Inspect the suction filter for high vacuum (cavitation) first; if suction vacuum is nominal, check radial clearances between the idler spindles and casing liner.

Is it possible to reverse the discharge and suction flow directions?

The pump is structurally direction-dependent due to internal balancing lines and seal chamber relief channels. Reversing the motor rotation will not reverse flow correctly and will subject the mechanical shaft seal to unvented high pressure, causing mechanical destruction. Always adhere to the directional arrows cast onto the pump body.