Positive-displacement screw pumps split into three working geometries — single (progressing cavity), twin, and three-screw — and the wrong pick is the most common cause of premature wear, cavitation, or shaft seizure in 2026 procurement [S1][S7].
Verified 2026 China-sourced price bands run from US$299.70 per piece for heavy-oil screw spindles to US$1,997.90 for higher-spec shaft assemblies, with single-screw pump MOQ pricing starting at US$1,200 per piece (Tianjin port, 100-piece monthly capacity) [S2][S4].
Single-Screw, Twin-Screw, and Three-Screw: How Geometry Drives Duty
A single-screw (progressing-cavity) pump uses one helical rotor turning inside an elastomeric stator to move viscous, shear-sensitive, or solids-laden fluids at low to moderate differential pressure [S1][S7]. A twin-screw pump carries two intermeshing rotors in a close-clearance casing, handles higher pressures and clean lubricating fluids, and runs with low pulsation. A three-screw pump — the 3G series being the workhorse pattern — uses one driving rotor and two driven rotors, displacing clean lubricating oil and fuel oil at moderate pressure with smooth flow [S1][S5].
Three-screw 3G-series casings specified on 2026 catalogues are cast in HT200 grey iron, QT450-10 ductile iron, ZCuSn10P1 tin bronze, or ZG270-500 cast steel; driving and driven screws are machined from 16MnCrS5 case-hardening steel, 40Cr, 45 medium-carbon steel, or 38CrMoAl nitriding steel for wear resistance [S5]. Single-suction stainless-steel and self-priming variants appear on the 2026 China-Single-Suction-Screw-Pump category, including chemical-process builds with fiberglass-reinforced flow paths [S6].
Price Bands and Cost Drivers on 2026 Sourcing Platforms
Made-in-China.com lists 7,367 screw-pump manufacturers and 154,725 product listings as of the 2022 baseline that still drives the 2026 index, with the heavy-oil screw spindle category showing a US$299.70-1,997.90 per-piece band on 2026-07-07 quotations [S1][S4]. The G Single-Screw Pump listing sets a US$1,200 per-piece MOQ with 100-piece monthly capacity out of Tianjin, payment terms T/T [S2].
Yuhong permanent-magnet variable-frequency screw air compressor packages at US$630-642 per piece, MOQ 1, with 7.5/11/22/37 kW frame sizes, one-year warranty, and a single-suction, no-leak specification for sewerage, food, and chemical service [S3]. A screw pump buyer comparing air-end and liquid-end units must therefore treat kW rating, suction method, and certification separately from rotor geometry.
Selection Criteria: Viscosity, Pressure, Cleanliness, and Fluid Compatibility
Viscosity is the first filter: progressing-cavity single-screw pumps handle viscosities from roughly 1 cP (water-like) up to 200,000 cP or higher (heavy crude, sludge), while three-screw pumps lose efficiency above approximately 1,500-3,000 cP and are restricted to clean lubricating oils, hydraulic oil, and light fuel oil [S5][S7]. Differential pressure capability scales differently: single-screw pumps typically run up to 16-30 bar depending on stage count, twin-screw pumps can exceed 100 bar, and three-screw 3G-series units commonly sit in the 16-40 bar window for lubrication and fuel-oil service.
Fluid cleanliness is the second hard gate: the three-screw 3G series explicitly requires clean oil because tight rotor-to-bore clearances cannot tolerate abrasive particles; single-screw pumps tolerate solids-laden slurries because the elastomeric stator absorbs particulate [S5][S7]. Material compatibility is the third gate: HT200 and QT450-10 casings cover most hydrocarbon service, ZCuSn10P1 tin-bronze is used where corrosion or galling resistance matters, and 38CrMoAl nitriding steel is preferred on rotors running hot or dry briefly [S5].
Comparison Matrix: Single, Twin, and Three-Screw at a Glance
Side-by-side on 2026 selection criteria: single-screw wins on viscosity ceiling and solids tolerance, twin-screw wins on differential pressure, dry-run resistance, and clean-fluid efficiency, and three-screw wins on flow smoothness, low noise, and footprint for clean-lube duties [S1][S5][S7]. Three-screw 3G units carry the lowest entry price among the steel-rotor options (US$1,200 MOQ observed for the G Single-Screw variant, with comparable three-screw pricing indexed lower in the same category) [S2][S5].
For buyers already specifying progressive-cavity geometry, the stator elastomer — typically NBR, EPDM, or FKM — sets the fluid compatibility and temperature ceiling more than the rotor metallurgy does. For positive-displacement lube and fuel-oil circuits where pulsation matters, three-screw 3G series with ZCuSn10P1 casings and 38CrMoAl rotors is the conservative 2026 default. Buyers evaluating adjacent PD technologies can cross-check gear-pump vs magnetic-drive trade-offs before locking the screw spec.
Who Should NOT Pick a Three-Screw Pump
Three-screw pumps are wrong for slurries, sludges, or any fluid containing abrasive solids, because the close-running rotors and tight casing clearances are scored within hours by sand, scale, or polymer gels [S5][S7]. They are also wrong for shear-sensitive emulsions, where mechanical agitation in the rotor cavity breaks the emulsion.
Single-screw (progressing-cavity) pumps are wrong for clean, high-pressure hydraulic service above ~30 bar, because stator elastomers limit both pressure and temperature, and they are wrong for dry-running duty without a separate flush plan. Twin-screw pumps are wrong for very low-viscosity solvents below ~1 cP, where internal slippage destroys volumetric efficiency [S7].
Installation, Maintenance, and Common Failure Modes
Blackmer's published 2026 guidance for screw pumps handling viscous fluids and transfer service specifies seal flush on the packing or mechanical seal when the pumped fluid is below its vapour pressure or above 80 °C, and a relief or bypass line sized to full pump flow because screw pumps have no internal overpressure protection [S7].
On 3G three-screw units, the typical failure path is drive-screw bearing failure caused by radial load from misalignment or from running off the curve at low flow for extended periods; preventive practice is a minimum-flow-orifice bypass sized to 10-30% of rated flow and a coupling alignment check at every overhaul [S5]. For single-screw pumps, the dominant wear part is the stator elastomer — typical replacement interval is 2,000-4,000 hours on abrasive duty and 8,000+ hours on clean lube oil — and the rotor should be inspected for chrome-plating wear at the same interval [S7].
2026 Sourcing Signals to Track
The screw-pump spindle category refreshed pricing between 2026-06-25 and 2026-07-23, with the upper end of the band (US$1,997.90 per piece) holding steady across the listed three-screw and oil-pump-screw offerings [S4][S5]. G-type single-screw pump MOQ at US$1,200 with 100-piece monthly capacity out of Tianjin remains the floor reference for buyers negotiating volume terms [S2].
Trackable 2026 nodes: (1) published API 676 compliance for hydrocarbon service, which most 3G three-screw and twin-screw screw pumps claim but few single-screw progressing-cavity units do, and (2) ATEX/IECEx certification for Group II hazardous-area service, which is a non-negotiable filter for European chemical and refinery bids [S5][S7].
Spec-level background on the components involved: linear guide.