Alfa Laval LKH UltraPure Centrifugal Pump

The LKH UltraPure is the high-purity execution of Alfa Laval's LKH centrifugal pump platform. Alfa Laval aims it at biotechnology and pharmaceutical processes that need equipment with the highest material integrity, and builds it for cleaning-in-place.

What separates it from a general hygienic pump is mostly paperwork, and that is the honest way to describe it. Every LKH UltraPure arrives with the Alfa Laval Q-doc package, which exists to make qualification, validation and change control easier and to give proof of origin for inspection against Good Manufacturing Practice and ASME BPE requirements. The standard package carries a declaration of compliance with Regulation (EC) No. 1935/2004, a declaration to EN 10204 type 3.1, a declaration of compliance to U.S. Food & Drug Administration CFR 21 covering the non-metallic parts, a declaration to the U.S. Pharmacopeia for elastomers and polymers, a TSE/ADI declaration, a surface finish declaration, a passivation and electropolishing declaration where specified, 3.1 certification to EN 10204, and a pump performance test certificate. A hydrostatic test certificate, a surface measurement report and a delta ferrite report on the impeller are available on top of that.

Which points at the trade-off. If your process is a food or dairy CIP line and nobody is ever going to ask you for a material certificate, the documentation is cost you will not use, and a general hygienic centrifugal pump will move the same liquid. Specify the UltraPure when the validation pack is part of the requirement, not because the label sounds more careful.

On the build: all media-contacting steel components, the pump casing, impeller, impeller nut and back plate, are W. 1.4404 (AISI 316L) with 3.1 traceability to EN 10204. Inside surface finish is mechanically polished to Ra ≤ 0.5 as standard and the external finish is fibre brushed. A stainless steel shroud protects the motor and four adjustable stainless steel legs carry the unit. Options run to a mechanically polished Ra ≤ 0.8 or electropolished Ra ≤ 0.4 product-wetted finish, a passivated surface, FPM or FEP elastomers to the same USP Class VI specification, an impeller with delta ferrite at 1% maximum, a reduced-diameter impeller, a double mechanical shaft seal, and an ATEX-approved execution designated LKHex UltraPure. Alfa Laval gives a three-year warranty covering all non-wear parts, conditional on genuine Alfa Laval spare parts being used.

Channel Pumps supplies the LKH UltraPure and sizes it against your duty point.

The pump is a motor, an impeller, a pump casing, a back plate, a mechanical seal, legs, the pump shaft and connections, and an adaptor. The semi-open impeller turns with the shaft inside the casing. The blades pass energy to the fluid and move it in a circular direction, its velocity rises, and part of that velocity converts to pressure before the fluid leaves through the outlet. A compression coupling holds the stub shaft to the motor shaft in precise alignment.

The impeller does two jobs beyond moving liquid. Its vane design gives a low NPSH required, so the pump stays clear of cavitation on a suction that would trouble a lesser hydraulic. Its balance holes circulate process fluid through the shaft seal area, which cuts axial force and wear on both the seal and the motor bearings. That flow behind the impeller also makes the seal area cleanable and keeps the faces lubricated and cool.

The seal is where a specifier should concentrate, because it is the weak point in almost any pump. The LKH UltraPure uses an external, front-loading shaft seal with the spring and washers mounted on the atmospheric side, so the spring does not wear into the product and a change takes minutes. Both faces are silicon carbide. Alfa Laval machines them to a flatness of three light bands or less, measured at 20°C, where one light band corresponds to 0.3 µm across the whole sealing surface. The stationary ring is fixed to the back plate, which keeps the faces aligned after long running and vibration. The balanced design and the spring force equalise pressure in the seal area, which limits the risk of the seal opening under a pressure shock. A double mechanical seal is the option: flush water inlet pressure is capped at 5 bar on the LKH UltraPure-10 to -60 and 3 bar on the LKH UltraPure-70, consumption is 0.25–0.5 l/min, and the connections are 1/8" G. A defined O-ring groove positions the O-ring on the pump casing, giving metal-to-metal contact and a predefined compression with no crevices.

On hygiene, Alfa Laval's product leaflet states that the LKH UltraPure has an EHEDG certificate. The rest of the compliance picture sits in Q-doc, and it is worth reading what each declaration actually covers: the FDA CFR 21 declaration is scoped to the non-metallic parts, and the U.S. Pharmacopeia declaration to elastomers and polymers. For a hazardous area, Alfa Laval lists an ATEX-approved execution under the designation LKHex UltraPure, and that is a build you specify at order, not a certificate the standard pump carries.

The operating limits are firm. Maximum inlet pressure is 5 bar (500 kPa) across the LKH UltraPure-10 to -70. The temperature range is -10°C to +140°C with EPDM elastomers. Flush media is capped at 70°C, and the flush housing may be sterilised to 125°C with the pump stopped. Drive is a foot-flanged motor to IEC metric standard, two-pole at 3000/3600 rpm or four-pole at 1500/1800 rpm on 50/60 Hz, IP55 with a drain hole and labyrinth plug, insulation class F.