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Godwin Rotary Lobe
Xylem Pumps › Godwin Pumps › Rotary Lobe Pumps
Rotary Lobe GRL Series
Godwin Rotary LobePositive Displacement · High Air Handling · Low HP
Positive-displacement rotary lobe pumps for on-site dewatering applications including wellpointing, sock dewatering, and air-handling-intensive service. Available in 6, 8, and 12-in models — delivers higher flow rates with less horsepower than centrifugal alternatives.
3,175
Max GPM
29 ft
Suction Lift
425
Max CFM Air
3 Models
Available
Why Rotary Lobe
Positive-displacement design solves problems that centrifugal pumps can't — high air content, intermittent flow, low NPSH, and viscous fluids.
Higher Flow Per HP
Positive displacement delivers more GPM per HP than equivalent centrifugal pumps — lower fuel costs over project lifetime.
High Air Handling
Up to 425 CFM air handling capacity — critical for wellpoint and sock dewatering where air-water mixture is the norm.
Removable Front Cover
Inline maintenance access without disconnecting piping. Service impellers and seals without breaking system connections.
Reduced Vibration
Lower rotational speed than centrifugal at equivalent capacity — less vibrational wear on downstream piping and equipment.
Formed Steel Casing
Heavy-gauge formed steel pump casing for extended wear life in continuous duty. Engineered for rental-fleet durability.
Diesel or Electric Drive
Both drive options available. Electric drive paired with VFD allows precise flow control for variable wellpoint demand.
Rotary Lobe Models & Specifications
Engine speed is geared down to pump speed via gear-reduction box. Engine speeds shown are at maximum operating condition.
| Model | Pipe Conn (in) | Max Cap (GPM) | Disp (gal/rev) | Max Pressure (psi) | Pump RPM | Engine RPM | Air (CFM) | Wt (lb) |
|---|---|---|---|---|---|---|---|---|
| GRL150 | 6×6 | 325 | 0.65 | 30 | 500 | 1,875 | 45 | 4,200 |
| GRL200 | 8×8 | 1,560 | 2.6 | 30 | 500 | 2,000 | 208 | 5,000 |
| GRL300 | 12×12 | 3,175 | 2.6 | 30 | 500 | 1,500 | 425 | 7,000 |
Source: Godwin Product Catalog 07.2015 (US). Gear reduction ratios: GRL150 = 3.85:1, GRL200 = 3.75:1, GRL300 = 3.66:1. Suction lift: 29 ft.
Rotary Lobe Configuration Options
Rotary lobe pumps require careful application matching — they're not interchangeable with centrifugal pumps for all duties.
Available Configurations
- Drive type. Diesel (Tier 4 Final) or electric (230/460 V three-phase, VFD-recommended).
- Wetted parts. Standard cast iron pump body and lobes. Optional metallurgy upgrades for chemical service — specify fluid characteristics.
- Pressure limit. 30 psi maximum working pressure — do not exceed. For higher pressure service, centrifugal HL series is the right choice.
- Speed control. Variable engine speed (diesel) or VFD (electric) recommended for flow modulation. Positive displacement = flow proportional to speed, so speed control = flow control.
- Mounting. Skid base standard. Trailer mounting available for shorter-duration / portable applications.
- Maintenance. Removable front cover allows lobe and seal service without piping disconnection. Plan for periodic lobe inspection in abrasive service.
Rotary Lobe Applications
Rotary lobe shines where centrifugal pumps lose efficiency or fail entirely — high air content, intermittent flow, viscous fluids.
Wellpoint Vacuum Service
Primary application — high air-handling capacity makes rotary lobe ideal as the vacuum pump in wellpoint dewatering systems.
Sock Dewatering
Geotextile dewatering tube fill operations where slurry contains entrained air and viscosity is high.
Sludge Transfer
Low-shear positive displacement preserves floc structure in sludge transfer between treatment stages.
Bilge / Tank Dewatering
Bilge pumping where intermittent slugs of water and air would cavitate a centrifugal pump.
Honey-Wagon / Vacuum Truck
Vacuum truck-style applications requiring sustained high-CFM air handling.
Low-Pressure Process Transfer
Plant transfer applications under 30 psi where high air handling, low NPSH, or viscous fluid handling rules out centrifugal.
Air Handling or Wellpoint Service?
Rotary lobe is the right answer for high-air, low-NPSH, or viscous service. Quote within 24 hours.
Rotary Lobe FAQ
When should I use rotary lobe instead of centrifugal?
Three signals point to rotary lobe: (1) High air content in the fluid (would cavitate centrifugal). (2) Need for precise flow control (positive displacement = predictable flow per RPM). (3) Viscous fluid (centrifugal efficiency drops sharply with viscosity). For clean-water dewatering at moderate head, centrifugal CD-series is more efficient and lower cost.
Why is the pressure limit only 30 psi?
Rotary lobe geometry is optimized for high flow at low-to-moderate pressure. Higher pressures require tighter tolerances, more robust seals, and create slip losses that destroy efficiency. For pressure service over 30 psi, centrifugal HL-series is the right answer.
How much air can rotary lobe handle?
Up to 425 CFM on the GRL300. This is the primary value proposition vs. centrifugal — a centrifugal pump losing prime to air is useless. Rotary lobe pumps air-water mixtures continuously without losing capacity.
Do I need VFD on the electric models?
Strongly recommended. Positive-displacement flow is directly proportional to RPM — VFD gives you precise flow control without throttling. In wellpoint applications where demand changes as the water table drops, VFD pairing is essentially mandatory for energy efficiency.
How does rotary lobe handle abrasives?
Cast-iron lobes handle light abrasives reasonably; for heavy abrasive service (sand, grit, drilling mud), expect accelerated lobe wear. For sustained abrasive duty, hard-faced lobe upgrades are available — specify fluid abrasiveness when ordering. For very abrasive service, Heidra SG (Slurry Gate) submersibles are often a better answer.
Need a Rotary Lobe Quote?
Tell us your application — fluid characteristics, air content, flow target. Quote within 24 hours.
281.664.8000Godwin® is a trademark of Xylem Inc. and its subsidiaries.
Watermain Supply is a DBA of E4 Industrial LLC, an authorized Xylem dealer based in Houston, Texas.
Watermain Supply is a DBA of E4 Industrial LLC, an authorized Xylem dealer based in Houston, Texas.
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