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The NKL Series are light duty centrifugal pumps for handling heat transfer media. They are particularly suited to perform as circulating pumps in industrial heating plants. The dimensions and performance range comply with the requirements of EN 733. Thus, the performance range is subdivided such that best efficiency is granted at all service conditions.
The performance range covers capacities up to 1000 m³/h and differential heads up to 90m. The maximum allowable operating temperature PT is 340°C without additional cooling.
NKL pumps are single stage, single flow volute casing pumps of horizontal back-pull- out design with end suction and top discharge flanges. The back-pull-out design allows disassembly of the bearing bracket unit, complete with impeller, intermediate casing and mechanical seal without removing the volute casing from the piping system.
The "N10q" seal, available as standard with NKL pumps, has metallic bellows and auxiliary gland packing. Conforming to DIN 4754, the seal has rotating, double-walled bellows and wear-resistant mating faces of SiC. This ensures a long service life, even when pumping hot oils containing solids such as coke particles and pipe scale. The rotation of the bellows and the conical shape of the seal chamber resists clogging and seizing of the bellows.
NKL pumps have closed impellers, cast-en-bloc, hydraulically balanced by throttle gap and relief bores to minimize axial loads. All impellers are dynamically balanced acc. to DIN ISO 1940 part 1, at a balance grade of G 6.3, that grants a smooth and vibration free operation of the pump. The impellers are arranged on the pump shaft in overhung position and are fixed by keys and shaft nuts with Heli-Coil inserts.
The pump shaft is carried on two antifriction bearings positioned at the pump and coupling sides outside the pumped liquid. There is no additional sleeve bearing unit available in the fluid. Oil lubrication is standard with the oil level in the bearing bracket controlled by a constant level oiler. The expected service life of the bearings is 20,000 operating hours.