The family of single-unit cradle-mounted pumps of GRUNDFOS Company has been enlarged. Now the whole line of NB and NK pumps is also available in the stainless steel make. Offered to customers along with high reliability is the power efficient solution for application both in main technological processes and in subsidiary applications.
The single-unit cradle-mounted pumps are intended for pumping large volumes of liquids that match water with the chemical composition, density and viscosity. In large construction projects the cradle-mounted pumps shall serve as the main components of heating and water supply systems, whereas in existing systems they may be used as auxiliary elements for enhancement of the efficiency of operation or equalization of the height pressure difference in urban water supply mains. These pumps are simply irreplaceable in industry and in communal services for increasing the water head in the mains.
For many years the line of NB and NK pumps with cast iron flow system was a synonym of dependability in pumping over of water. The complete variety of single-unit cradle-mounted pumps is supplemented with models of stainless steel make that are certified according to ISO 2858 standards and meant not only for pumping over of sea water, but also of explosive and aggressive liquids. The «Grundfos» Company offers a wide spectrum of nonstandard models of pumps and stainless steel pumps of NK, NKG, NB and NBG series of special design that have been engineered and manufactured for industrial applications providing supplemental options to meet all the requirements of technological processes.
Face seal
For pumping the chemical agents with different properties the face seals with EPDM, FKM, FFKM, FXM elastomers are proposed. Besides the opportunity of utilization of advanced materials the customers are in a position to select the required structure of the face seal either of the type of single seal, or the «tandem» or «back-to-back» type double seal, or at last the cartridge face seal. With the mentioned options it turns possible to safely pump over even highly imflammable or poisonous substances. The pump may be additionally equipped with all required accessories and a system for flushing the face seal chamber, as, e.g., in case of the «tandem» type double sealing.
Bearing assembly
The main attention during the development efforts was devoted to the problem of cutting the costs of maintenance and repair of pumps to the minimum. In particular, the choice of the design of bearing assembly is crucial for operation of the pumping unit as a whole. For operation of pumps under complicated service conditions we have elaborated strengthened bearings furnished with an automatic batching device for well-timed lubrication, the lubricant being the grease lubricant or heavy oil. The strengthened autolubricated bearings are especially of use in cases when the pressure on intake side of pump is high and the minimum of 100 000 hours of continuous operation is guaranteed. It is recommended to use the bearings with (automatic) lubrication system for pumping over of high temperature agents. Besides, the NKG type pumps may be furnished with appropriate fittings for inclusion of bearing temperature measurement sensors and vibration level metering transducers in the bearing unit.
Electric motor
All pumps of NK, NKG, NB and NBG model series may be supplied in complete sets with electric motors that nowadays satisfy the highest requirements of the Directive guidelines of European Commission for IE3 Power Efficiency Class. The electric motors that satisfy or exceed the requirements of the European Commission are marked with special symbol Grundfos Blueflux®. For use of pumps in potentially explosive hazard environment the «Grundfos» Company proposes electric motors in an explosion-proof make in conformity with ATEX directives. All the pumping units are supplied with ATEX certificates.
Pumping constituents
The Grundfos stainless steel pumps are designed for high efficiency pumping of corrosive media of every sort and kind, and demonstrate the reliability of operation in the absence of the risk of development of corrosive processes. The scope of special versions of pumps is intended for pumping over of liquids with temperature ranging from -25 °C to +160 °C under pressure up to 25 Bar. All model series may be executed according to two classes of DIN stainless steel casing pumps: EN 1.4408 or EN 1.4517. As an option the flow passage of the pumps may have a special composite coating to protect the passage against mechanical impurities contained in the liquid, owing to which the service time of the pump as a whole will increase.
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