ANSI HI-5.1-2000 pdf download Sealless centrifugal pumps
5.1 Types and nomenclature
5.1.1 Scope To develop the definitions and construction for sealless pumps that are driven by canned motors or magnetic couplings. These standards include types and nomenclature; design and application; installation, operation and maintenance; and test. Not included are submersible wastewater pumps which do not have external shaft seals and are therefore not susceptible to external shaft leakage.
5.1.1.1 Objective To clearly outine the information necessary to define and describe the construction and use of sealless pumps.
5.1.1.2 Introduction The sealless pump is used when there is a need to contain toxic, dangerous and/or valuable fluids. Appli- ation may be dictated by space, noise, environment, rsafety regulations. This section outlines components of sealless centrifugal type pumps. The driven shatft is completely contained in a pressurized vessel containing the pumped fluid. The pressurized vessel or primary containment device (chamber) is sealed by static seals such as gaskets or Orings.
The power required by the driven shaft is transmitted through a containment barrier. Methods include (1) the “canned motor pump” with a liner (can) placed between an induction motor’s armature and stator; (2) the “magnetic drive pump” with a shel(s) located between an outer rotating element with permanent magnet(s) and a mating inner ring which follows the driving magnets. The inner rotor may have permanent magnets or it may be an induction device. See Figure 5.1 for a diagrammatic breakdown of the types of sealless centrifugal pumps.
5.1.2 Canned motor pump (CMP)
5.1.2.1 Close coupled end suction Figure 5.2- In this group, the impeller(s) is mounted on the end of the shaft which is overhung from its motor bearing supports. The impeller is mounted directly on the rotor assem- bly making one rotating assembly. The bearings are supported by housings at each end of the rotor assembly.7 The motor components are protected from the process liquid by non-magnetic liners (shells). During operation, the motor section and bearings are cooled and lubricated by the process liquid by internal circulation, external circulation or by separate liquid flush.
5.1.2.2 Close coupled in-line Figure 5.3一In this group, the pump and motor are mounted vertically. A single stage overhung impeller is used in conjunction with a casing with in-line flange connections. Motor and bearings are cooled and lubricated by the process liquid.
5.1.2.3 Separated pump and motor Figure 5.4一This group has single or multistage overhung impellers; however, the pump and motor are separated by a thermal barrier, usually an air space. The impeller is mounted on the rotor assembly which is supported by bearings at each end. The rotor assem- bly contains an auxiliary impeller which circulates the process liquid in the motor section through a heat exchanger for control of the fluid temperature.