Seal less Rotary Pumps

4.0 Scope

This standard covers the unique features of sealless rotary pumps and includes sections on: types and nomenclature; definitions; design and applications; installation, operation and maintenance; and test.

Because of the variety of rotary pump configurations available and the broad range of applications, familiarization with ANSI/ HI 3.1–3.5 Rotary Pumps and ANSI/HI 3.6 Rotary Pump Tests is recommended.

4.1 Types and nomenclature

4.1.1 Objective

To clearly outline information necessary to define, apply, operate and maintain sealless rotary pumps.

4.1.2 Introduction

This standard covers magnetically coupled rotary pumps (sometimes called magnetic drives or magnetic couplings) which eliminate the shaft seal. These pumps utilize permanent magnets to drive an internal rotating assembly through a magnetically permeable containment shell (canister). There are no openings or leak paths through the shell, and the rotor and bearings are completely submerged in the fluid. There are static seals in the pump.

The coupling referred to is the radial synchronous magnetic type. Other means of eliminating the shaft seal are axial magnetic couplings, eddy current (slip) drives and canned motors. Although concepts within this standard apply, these devices have not been included, since they are considered to be currently in limited distribution and focused information on the synchronous magnetic coupling is of greater importance.

4.1.3 Types of magnetic drive configurations

ANSI/HI 3.1–3.5-2000, Rotary Pumps, Figure 3.1, provides a diagrammatic breakdown of types of rotary pumps. Since this family of products is so broad, this standard does not attempt to provide guidance or figures with each type in a sealless configuration.

The figures included are to illustrate the fundamental magnetic drive configurations and those components that are typically applicable to various types of rotary pumps:

– Figure 4.1 Close coupled – vane type magnetic drive pump;

– Figure 4.2 Separately coupled internal gear magnetic drive pump with secondary control;

– Figure 4.3 Separately coupled screw type magnetic drive pump.

The definition of component parts is included in Table 4.1 — Nomenclature.

Part name	Number	Definition
Adapter	71	A machined piece used to permit assembly of two other parts
Bearing, inboard	16	Rolling element bearing in the frame nearest the pump
Bearing, outboard	18	Rolling element bearing in the frame closest to the motor
Bushing, bearing, inboard	235	Sleeve type bearing in the drive section, closest to the liquid chamber, which is lubricated by the pumpage
Bushing, bearing, outboard	237	Sleeve type bearing in the drive section, closest to the mag-nets, which is lubricated by the pumpage
Bushing, idler	240	Sleeve type bearing in the idler, closest to the magnets, which is lubricated by the pumpage. The bushing rides on the idler pin
Casing	1	The external part that surrounds the periphery of the pumping chamber
Cover, bearing outboard	37	An enclosing plate for the outboard end of the bearing housing
Cover, casing inboard	239	The end portion of the magnetic drive assembly that houses the driven magnet assembly, shaft and containment shell
Cover, casing	243	A body in which the outboard bushing is mounted
Cover, suction	9	A removable piece which allows the inlet nozzle to be used to enclose the suction side of the casing
Disc	245	Replaceable element to maintain close clearance along the rotor sideface
Frame	19	A member of a pump to which is assembled the rotating outer magnet assembly and the drive motor or bearing housing
Gasket	73	Resilient material of proper shape and characteristics for use in joints to prevent leakage
Housing, bearing	99	A body in which the bearing is mounted
Idler gear	8	The driven element in internal gear rotary positive displace-ment pumps
Idler pin	3	Part on which the idler gear rotates. Unique to internal gear rotary positive displacement pump configurations
Key, coupling	46	A parallel-sided piece used to prevent the shaft from turning in a coupling half
Key, magnet drive	238	A parallel-sided piece used to prevent the shaft from turning in the inner magnet assembly
Locknut, bearing	22	Locking device utilized to fix a bearing position on a shaft
Lockwasher	68/69	A device to prevent loosening of a nut
Magnet assembly, inner	230	The permanent magnet or induction device assembly attached to the pump shaft, located within the containment shell and driven by outer magnet assembly
Magnet assembly, outer	232	The permanent magnet assembly attached to the power drive shaft, located outside of the containment shell and driven by a driver
Port, instrumentation	262	Access port to secondary casing for instrumentation required for detection of primary containment shell leakage
Ring, rub	252	A replaceable ring mounted in or on the bearing housing and/ or outer magnet assembly. It is used to prevent the outer carrier from hitting the containment shell if the rolling element bearings in the power end fail.
Rotor	2	A rotor rotates in the pumping chamber and is the primary ele-ment through which drive power is applied. Within some types of rotary pumps, it may be given a unique part name such as gearorscrew.
Seal, bearing housing	169	A contact seal for a bearing housing
Seal, secondary, mechanical	80	A device mounted on the drive shaft to maintain the secondary pressure boundary in a secondary containment system
Shaft, drive	6	The cylindrical member on which the rotor is mounted and through which power is transmitted to that rotor
Shaft, pump	12	The cylindrical member which transmits power from the driver to the outer magnet assembly
Shell, containment	231	The member that separates the inner and outer magnet assemblies. It also forms the barrier between the pumpage and the secondary containment.
Tube, circulation	251	A tube through which process liquid is piped for cooling of drive section
Vane	104	Element in a rotary vane pump that is housed by the rotor and extends into the pumping chamber. In cooperation with the casing and endplate, it carries the liquid and provides continuous sealing.

 

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