Alfa Laval OS Twin Screw Pump

The Alfa Laval Twin Screw Pump combines process duties typically handled by positive displacement with Cleaning-inPlace (CIP) duties typically handled by centrifugal pumps. This provides a robust and reliable platform that offers greater process flexibility. Designed for process flexibility, the Alfa Laval Twin Screw Pump is built on a robust, reliable platform that meets stringent hygienic standards.

It is capable of handling both product transfer and CIP. Its low pulsation characteristics and excellent solids-handling capability reduce the risk of product damage, thereby improving product quality. The pump is designed according to the most stringent hygienic design standards and with verified, effective CIP. 

Applications

Designed for handling sensitive, abrasive and high and low viscosity fluids, the Alfa Laval Twin Screw Pump is ideal for use in hygienic applications across the dairy, food, beverage, and home and personal care industries. Quiet and virtually pulse-free, the pump provides smooth and gentle operation, making it an excellent choice for handling sensitive products.

The two-in-one operation provides easy handling of process media of varying viscosities as well as CIP fluids. This simplifies piping and pump control, cutting costs and minimizing contamination risks. Superior suction performance with excellent lift capability and low NPSHr provides installation flexibility and increases product recovery. The Alfa Laval Twin Screw Pump is available in twelve models based on four frame sizes. Each frame size is available with three different screw profiles for varying pressure, flow and solids-handling capabilities.

Benefits

• Greater process flexibility
• Ease of service, increased process uptime
• Robust reliable design, reducing the cost of ownership and increasing process uptime
• Improved product quality
• Exceptional hygiene and cleanability

Standard design

All media contacting steel components, like pump casing, front cover and feed screws are in W. 1.4404 (AISI 316L). Furthermore, the pump casing is diffusion hardened. A stainless steel gearbox, end cover and foot ensure increased life and assist in washdown. The gearbox is designed with the timing gears located between the bearing sets, rather than external to them. This allows the bearing location to be optimized in order to provide maximum support to the shaft assembly, thereby providing a robust rigid design.

The internal gearcase design optimizes oil circulation to both sets of bearings and the timing gears with an oil sump design. This improves the lubrication effect on both bearings and timing gears, minimizing the energy produced due to friction and thereby reducing heat generation within the pump gearbox. The front-loading, self-setting cartridge design makes it easy to replace the shaft seal while the pump is in place. Single, single flush and double mechanical cartridge seals are available. All options are fully front-loading and interchangeable. The Alfa Laval Twin Screw Pump can be supplied either as a bare shaft pump or mounted on a base plate complete with coupling, guard, shroud and a direct coupled motor or a gear motor for easy, plug-and-play installation.

Working principle

The Alfa Laval Twin Screw Pump is a positive displacement pump. As the pump rotates, the intermeshing of the two contra-rotating screws, along with the pump casing, form volumetric chambers. These chambers fill with the pumped fluid and move the fluid axially from the suction side of the pump to the higher pressure discharge side.

Process Flexibility

A) 2 in 1 Operation
Ability to easily handle process media of varying viscosities as well as CIP fluids, simplifying piping and pump control, cutting costs and minimizing contamination risks. 

B) Suction Performance
Superior suction performance with excellent lift capability and low NPSHr provides installation flexibility and increases product recovery.

C) Product Quality
Smooth and gentle in operation with low pulsation characteristic and excellent solids handling capability, reduces the potential for product damage.

Service & Reliability

D) Truly Front Loading Seal
Quick, easy seal replacement with the pump in place is made possible, thanks to a cartridge seal with a truly front-loading, self-setting design. This maximizes process uptime and minimizes maintenance costs. An optional seal service kit program adds maintenance flexibility and cuts operating costs.

E) Robust Gearbox
A sturdy, all stainless steel gearbox with timing gears located between bearings, provides an optimised bearing span giving balanced loading of the shaft assembly, reducing vibration and noise, increasing component life and reliability. Oil chamber design provides for enhanced bearing and gear lubrication, minimising gearbox running temperature, increasing bearing life.

F) Simplified Timing
Easy access to timing gears whilst pump is in position, simplifies process of screw retiming without the need to drain gearbox oil or
remove coupling and motor. 

Operational Safety

G) Hygienic Design
A clean, external stainless steel finish with profiled elastomers and mechanical seals fully surrounded by product. Designed for maximum cleanability utilising FDA conforming materials, the pump is both EHEDG and 3A certified. 

H) Safer Environment
The combination of optimized gearbox design and excellent hydraulic performance provides for quiet pump operation reducing noise emissions to a minimum. Furthermore, running temperature is minimized, increasing workplace safety. An optional ATEX version allows use in hazardous zones.

Technical Data

Standard specification
Pump casing: . . . . . . . . . . . . . . . . . . . . . W. 1.4404 (316L), diffusion hardened
Screws, front cover, seal housing: . . . . W. 1.4404 (316L)
Inside surface finish: . . . . . . . . . . . . . .  Mech Ra ≤ 0.8
Gear box: . . . . . . . . . . . . . . . . . . . . . . . . Stainless steel
Base plate: . . . . . . . . . . . . . . . . . . . . . . . Stainless steel
Coupling guard: . . . . . . . . . . . . . . . . . .  Stainless steel
Product wetted elastomers: . . . . . . . . . EPDM
Other elastomers: . . . . . . . . . . . . . . . . . FPM
Shaft seal: . . . . . . . . . . . . . . . . . . .. . . . . Single flush
Rotary seal face: . . . . . . . . . . . . . . . . . . Silicon Carbide
Stationary seal face: . . . . . . . . . . . . . . . Silicon Carbide

Shaft seals
Single, Single flush and double mechanical cartridge seals available. All options are fully front loading and interchangeable.
Max. flush pressure, single flush: . . . . . . . . . . . . . . . . 0.5 bar
Max. flush pressure, double mechanical: . . . . . . . . . .16 bar (max. 6 bar over product pressure)
Water consumption, single flush and double mechanical: . . . . . . . . . .0.5 l/min.
Flush connections, OS12-36: . . . . . . . . . . . . . . . . . . G 1/4″ or NPT 1/4″
Flush connections, OS42-46: . . . . . . . . . . . . . . . . . . G 1/2″ or NPT 1/2″

Pressure
Max. inlet pressure: . . . . . . . . . . . . . 16 bar
Max. discharge pressure: . . . . . . . . .16 bar

Temperature
Max. process temperature: . . . . . . . . . . 100ºC
Max. CIP/SIP temperature: . . . . . . . . . .150ºC

Motor
Direct coupled motor, 4, 6 or 8 poles, or gear motor, 4 poles, to IEC metric standard, 50/60 Hz, suitable for frequency conversion, IP55, insulation class F.

Warranty
Extended 3-years warranty on Alfa Laval Twin Screw pumps. The warranty covers all non-wear parts on the condition that genuine Alfa Laval Spare Parts are used.

Operating Data

Dimension (mm)

Pump shown with tri-clamp, suction and discharge connections.

Options

• Single mechanical shaft seal
• Double mechanical shaft seal
• Silicon Carbide/Carbon seal faces
• Product wetted elastomers in FPM or FFPM
• Diffusion hardened screws
• Heating jacket
• Rectangular inlet
• Hydrostatic testing with certificate
• Reversed flow
• Bottom inlet or outlet
• Stainless steel shroud covering coupling and motor
• Baseplate fitted with adjustable stainless steel ball feet
• ATEX approval

Pump sizing
In order to correctly size a twin screw pump some essential information is required. Provision of this information listed below enables our Technical Support personnel to obtain the optimum pump selection. Specific CIP data are important as well.

Product/Fluid Data

• Fluid to be pumped
• Viscosity
• Pumping temperature, minimum, normal and maximum
• Cleaning in Place temperature(s), minimum, normal and maximum

Performance Data

• Flow rate, minimum, normal and maximum
• Discharge head/pressure (closest to pump outlet)
• Suction condition

Keeping you processing

For more information about our products and services please get in touch!

JAMIE WETHERILL
Internal Sales Manager

Call: 01777 712101
Email: jamie.wetherill@moodydirect.com