SRU

SRUApplication

The SRU range of rotary lobe pumps has been designed for use on wide ranging applications within the Brewing, Dairy, Food, Pharmaceutical and Chemical industries. The SRU pump can handle from low to high viscosity media with its characteristic smooth, low shear pumping action being ideal for products such as creams, gels, emulsions, aerated mixtures, and delicate cells and organic solids in suspension.

The SRU range is suitable for CIP (Cleaning In Place) and conforms to USA 3-A Sanitary Standard. In addition the SRU pump range is certified by EHEDG (European Hygienic Equipment Design Group) as fully CIP cleanable to their protocol. The SRU pump range is also classified for use in potentially explosive atmospheres under the ATEX Directive 94/9/EC Group II, Categories 2 & 3, with temperature classification T1 to T4. The SRU range is compact in size and highly efficient, capable of flow rates up to 106 m³/h and pressures up to 20 bar. The modular design provides for greater application flexibility and cost effective maintenance.

The SRU range is compact in size and highly efficient, capable of flow rates up to 106 m³/h and pressures up to 20 bar. The new improved modular design provides for greater application flexibility and cost effective easy maintenance.

Standard Design Pump Gearbox

The SRU pump with its conventional lobe pump design concept has a robust cast iron gearbox, which provides maximum shaft rigidity and easy oil seal replacement. The SRU range in series 1-4 has a universal gearbox design. This gives the flexibility of mounting pumps with the inlet and outlet ports in either a vertical or horizontal plane by changing the foot and its position. The SRU range in series 5 & 6 has dedicated gearbox castings, which also allows the inlet and outlet ports to be in either the vertical or horizontal plane.

Pump head Construction

The SRU in standard specification has sanitary design full bore inlet and outlet ports to International Standards, maximising inlet and outlet port efficiency and NPSH characteristics. Enlarged diameter and rectangular ports are also available to handle very high viscosity products.

The SRU in standard specification has tri-lobe rotors with the option of bi-lobe rotors for handling fluids containing large delicate solids. All rotors are available in three temperature ratings allowing the pump to be operated at maximum process temperatures of 70°C, 130°C and 200°C for both fluid pumped and CIP.

Documentation

How It Works

Construction

Alfa Laval rotary lobe pumps are positive displacement pumps with rotor case, rotor case cover, rotors, rotor nuts, shafts, gearbox and shaft seals and elastomers, which are available in different materials. The pumps operate with no internal contacting parts in the pump head.

The SRU can be supplied either as a bare shaft pump or mounted on a base plate complete with coupling, guard, gear motor and shroud for easy plug-and-play installation.

The standard materials of construction are 316L stainless steel for all wetted parts and painted cast iron for the gearbox. Other materials are available on request.

Operating principle

A gear train in the pump gearbox drives the rotors and provides accurate synchronization, or timing, of the rotors. The contra-rotating propulsion system has two rotors spinning in opposite directions within the pump head. Fluid is carried through the pump in the cavities formed between the dwell of the rotor and the interior of the rotor case. The illustration (below) shows the displacement of fluid from pump inlet to outlet.

Rotarylobepump-operatingprinciple

The movement of the counter rotating rotors creates a partial vacuum that allows atmospheric pressure or other external pressures to force fluid into the pump chamber. As the rotors revolve, an expanding cavity forms, filling with fluid. As the blades disengage, each dwell forms a cavity. As the rotor blades engage, the cavity diminishes and fluid is, displaced into the outlet port.

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