Booster unit with NKV multi-impeller vertical pumps with coupling; designed for pressurization and heating circulation in commercial building service as standard. In all models, the parts in contact with the liquid are made of AISI 304 stainless steel (AISI 316 stainless steel, X version, only on request). They are particularly versatile, thanks to the center distance between the 2 in-line ports, designed to maximize interchangeability. Starting from 5,5 kW models, the silicon carbide-graphite mechanical seal can be removed without removing the motor. Mechanical seals for aggressive liquids and different connections (round, oval, Victaulic, clamp flanges) available on request. All the models are WRAS and ACS certified for use with drinking water. Rigid coupling to IE3 high energy efficiency electric motors.