Positive displacement pumps

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.

Dimension
PUMP SHOWN WITH TRI-CLAMP, SUCTION AND DISCHARGE CONNECTIONS

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.

Tecnical 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.