A sanitary twin screw pump applies the gentle, pulse-free positive displacement of the standard twin screw to dairy, food, pharmaceutical, and biotechnology service — all product-contact surfaces SS 316L Ra <0.8 µm electropolished, Tri-Clamp connections, self-draining casing geometry, and mechanical seal rated for CIP (140°C) and SIP (121–135°C). Processing 0.5–500 m³/h at 1–1,000,000 cP, it transfers shear-sensitive emulsions, particulate-laden fruit and vegetable products, and viscous biological fluids with validated cleanability and zero contamination — 3-A Standard 4-XX and EHEDG Doc. 35 certified.
The twin screw geometry provides the lowest shear rate of all rotary positive displacement pump types — screw tip speed of 1–8 m/s generates shear rates below 2,000 s⁻¹ at maximum operating speed, preserving emulsion stability, biological cell integrity, and fragile food texture. The axial flow mechanism eliminates radial forces that centrifugal pumps impose on particles. CIP fluid enters through the pump inlet at minimum 1.5 m/s, passes through both screw bores and the timing gear housing vent, and exits through the discharge — validated cleaning to <10 ppm TOC without disassembly. Screws and bores are electropolished after final machining.
Challenges
Particle Damage at High Speed with Large Inclusions (Fruit, Nut, Solid Pieces)
Screw-to-bore clearance limits maximum particle size — oversized particles wedge between screw flight and bore, causing pump jam.
Screw Profile Surface Roughness Maintenance After Multiple CIP Cycles
Repeated chemical CIP erodes electropolished surface over time — Ra can increase above 0.8 µm after 500+ CIP cycles.
SIP Steam Condensate Removal from Screw Bore Dead Zones
Screw bore undercuts and flight root radii can trap condensate — prevents complete sterilisation without validated drain protocol.
Product Residue in Timing Gear Housing at Shaft Seal Interface
Shaft seal face between product zone and timing gear zone is a potential residue accumulation point.
Validation of Homogeneous CIP Coverage Across Full Screw Bore Length
Long screw bores (up to 1,000 mm) require validated CIP velocity across full length — inlet and outlet proximity creates velocity gradient.
Solutions
- Maximum Particle Size = 60% of Running Clearance (Pump Selection Criterion): Specify pump with running clearance ≥ 1.67× maximum particle size — standard selection criterion prevents blockage.
- Annual Electropolish Re-Treatment and Ra Measurement (Certificate per Unit): Planned annual re-polishing maintains Ra <0.8 µm — 5-year electropolish life cycle with annual certificate.
- Dedicated Steam Drain Port at Lowest Point of Each Screw Bore + Slope 3°: Drain port at bore bottom + 3° casing slope ensures complete condensate gravity drainage before SIP confirmation.
- Triple-Lip Shaft Seal (Product / Barrier / Gear Oil Separation): Triple-lip seal isolates product zone, barrier gas zone, and gear oil zone — zero cross-contamination at shaft.
- CFD-Validated CIP Flow Simulation + Inline Conductivity Verification: CFD simulation confirms >1.5 m/s in all bore sections; inline conductivity sensor verifies detergent penetration.
Applications
- Dairy: Milk, cream, yogurt, cheese curd, butter, ice cream mix — CIP/SIP validated; 3-A certified; gentle cell-preserving.
- Food & Beverage: Fruit pulp with pieces, tomato, sauce, jam, confectionery filling — gentle particle-preserving transfer.
- Pharmaceutical: Parenteral emulsion, oral suspension, cream, gel — Ra <0.8 µm GMP; Ra <0.4 µm sterile API.
- Biotechnology: Whole-blood, cell culture, fermentation broth, bioreactor transfer — ultra-gentle, shear rate <2,000 s⁻¹.
- Cosmetics: Premium lotion, serum, emulsion, face cream — gentle particle-preserving validated-clean transfer.
Models & Capacities
Type 1B — Sanitary / Hygienic Twin Screw Pump (3-A / EHEDG): Models & Capacities | |||||||||||
Model | Scale | Flow Rate [m³/h] | Screw Ø [mm] | Speed [RPM] | Max Press. [bar] | Max Particle Size [mm] | Shear Rate (max) [s⁻¹] | Max Viscosity [cP] | Surface Ra [µm] | Inlet/Outlet Tri-Clamp |
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STP-025 | Lab | 0.1–2 | Ø25 | 50–600 VFD | 10 | 0.3 | <500 | 500,000 | <0.8 | DN 10 TC |
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STP-040 | Lab/Pilot | 0.5–6 | Ø40 | 50–800 VFD | 10 | 0.5 | <800 | 500,000 | <0.8 | DN 25 TC |
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STP-063 | Pilot | 1–18 | Ø63 | 50–1,000 VFD | 16 | 0.8 | <1,200 | 500,000 | <0.8 | DN 40 TC |
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STP-080 | Pilot | 2–35 | Ø80 | 50–1,200 VFD | 16 | 1.0 | <1,500 | 500,000 | <0.8 | DN 50 TC |
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STP-100 | Production | 4–70 | Ø100 | 50–1,200 VFD | 20 | 1.2 | <2,000 | 500,000 | <0.8 | DN 65 TC |
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STP-125 | Production | 8–130 | Ø125 | 50–1,200 VFD | 20 | 1.5 | <2,000 | 500,000 | <0.8 | DN 80 TC |
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STP-160 | Production | 15–220 | Ø160 | 50–1,000 VFD | 25 | 2.0 | <2,000 | 500,000 | <0.8 | DN 100 TC |
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STP-200 | Production | 30–420 | Ø200 | 50–900 VFD | 25 | 2.5 | <2,000 | 500,000 | <0.8 | DN 125 TC |
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STP-250 | Large Prod | 60–800 | Ø250 | 40–750 VFD | 25 | 3.0 | <2,000 | 500,000 | <0.8 | DN 150 TC |
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STP-315 | Large Prod | 120–1,500 | Ø315 | 30–600 VFD | 25 | 4.0 | <2,000 | 500,000 | <0.8 | DN 200 TC |
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STP-400 | Large Prod | 250–2,800 | Ø400 | 20–500 VFD | 25 | 5.0 | <2,000 | 500,000 | <0.8 | DN 250 TC |
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