Sanitary Twin Screw Pump

Our Sanitary Twin Screw Pump (available as a Double Screw) is Self Priming and has been produced specifically for hygienic and sanitary applications within the food, chemical and pharmaceutical industries. The Screw Pump is machined from cast Stainless Steel AISI 316L with a surface roughness of <0.8 as standard (<0.5 on request) to provide increased corrosion resistance. Competitors’ units employ a cast iron gearbox with epoxy paint which can become eroded over time and need replacing/repairing.

The pump shafts are constructed from Duplex Stainless Steel 1.4462 to provide extra rigidity in operation. The pump can be fitted with several different sealing options and elastomer materials to suit almost any application. The Double Screw Pump design combines all the best advantages of Lobe, Peristaltic, Centrifugal & Circumferential Piston Pumps. The result is an incredibly versatile and robust pump that can be used for a plethora or even a combination of applications within enumerative industries.

How does a Twin Screw Pump work?

Our Sanitary Twin Screw Pump is a type of Rotary Positive Displacement Pump available with a double screw. Its operation is based on the counter-rotation of 2 screws or rotors in the pump casing. Both screws are mounted onto their own shafts which are supported by bearing cartridges mounted directly onto the pump casing. One of the pump shafts is externally driven and an internal gear assembly drives the other shaft in the opposing direction. The screws rotate synchronously in opposing directions without touching.

When the screws rotate and pass the suction port the volume between them increases and create a vacuum which causes the liquid to enter the suction port and the pump casing. During the rotation of the screws, a fixed amount of fluid is conveyed through the pump. As the screws approach the discharge port, the volume between them decreases, creating a pressure build-up, and causing the fluid to flow out of the discharge port.

• Double screw
• Speed range from 100 – 3600 rpm
• Fully EHEDG Compliant
• Pulsation-free pumping of both thin and highly viscous fluids from 0.5 – 1’000’000 cPs
• Large Free Passage of Solids up to 60 mm in diameter
• Dry Run
• Self Priming up to 8 m
• Reversible (8 Bar Max Discharge Pressure as standard, if up to 16 bar, bearing arrangement needs to be adjusted)
• Accurate flow control from 0.07 – 0.46 l/rev
• Discharge Pressures up to 16 Bar
• Variable fluid temperatures up to 140ºC
• Low NPSHr requirements, <2 m
• CIP/SIP friendly – minimal dead spaces
• Suitable for Shear Sensitive Fluids
• Suitable for pumping fragile solids
• Can be used for CIP feeding as well as product pumping – No need for a separate Centrifugal Pump for CIP.
• Wide variety of connection types
• Optional Heating & Cooling Jackets
• Optional large pitch screws for increased capacity and solids passage

• Process Pump and CIP Pump
• Suction
• Feeding
• Filling
• Displacement
• Supply
• Flush
• Dosing
• Loading, unloading and displacement
• CIP (Cleaning in Place) and SIP (Sterilisation in Place)
• Product displacement

The following Mechanical Seal variants are available:

• Single Mechanical Seal: EHP-PDSP
• Single Mechanical Seal with Quench or Flush: EHP-PDSP and Lip seal to 16 Bar
• Double Mechanical Seal: PP-PDSP
• Double Mechanical Seal with Quench or Flush: PP-PDSP and PA-PDSP to 16 Bar

For low pressure quenches the flushing system must have a capacity of 0.25 l/min @ 0.5 mwc. For pressurised flushes, the pressure must be 2 bar higher than the system pressure.