Chapter Six - Standardized chemical pump with canned motor in flameproof enclosures

Abstract

This chapter describes shaft sealing, antifriction bearings, and pump shafts. Most conventional chemical pumps are fitted with mechanical seals. Mechanical seals, however, are subject to permanent wear depending on the liquids to be pumped, which limits service life and precludes hermetical sealing, as a lubricating film is needed at the sealing faces. The standard design is based on a combination of the well-known hydraulic system of standardized chemical pumps in accordance with DIN 24256 or ISO 2858 and a canned standardized drive unit. The driving torque is transmitted by the electromagnetic field generated in the stator winding, which acts on the pump rotor via the can. In terms of explosion protection, conventional canned motor pumps used to be divided into two separate zones. The stator chamber—between motor housing and can—used to be classified as “flameproof enclosure.” The cooling principle is discussed in this chapter. The heat losses of the motor are dissipated from the rotor chamber indirectly. Pumped liquid is routed from the discharge side of the pump hydraulics through a heat exchanger installed in the rotor chamber, where it is heated up.