Cen­trifu­gal pumps and mag­netic drive pumps for dif­fer­ent in­dus­trial ap­pli­ca­tions

DEMM Engineering & Manufacturing - - PUMPS AND VALVES -

The fam­ily of in­dus­trial pumps usu­ally in­cludes API, ANSI and ISO mod­els. On the other hand, mag­netic driven pumps are de­signed for ser­vices where leak­ages can­not be tol­er­ated. Com­plete un­der­stand­ing of pro­cess­ing in­volved is the key in find­ing best pump so­lu­tion to each par­tic­u­lar pump­ing prob­lem.

Mag­net drive pumps (also known as mag­net­i­cal­ly­cou­pled pumps) vary from the tra­di­tional pump­ing style, as the elec­tric mo­tor is cou­pled to the pump by mag­netic means rather than by a di­rect me­chan­i­cal shaft. The pump works via a drive mag­net, ‘driv­ing’ the pump ro­tor, this elim­i­nates any shaft seal­ing re­quired by the pump. if the load of the pump is too great. By the mag­netic cou­pling ‘break­ing’, it means the pump does not over­load and get dam­aged. Elim­i­nat­ing the drive seals gets rid of leaks, fric­tion loss, wear and noise. It pro­vides com­plete sep­a­ra­tion of liq­uid from the pump drive, and nearly 100 per­cent trans­fer of mo­tor power into pump­ing power.

Liq­uids con­tain­ing fer­rous par­ti­cles are prob­lem­atic when a mag­netic drive pump is used. This is due to the par­ti­cles col­lect­ing on the im­peller mag­net, and over time caus­ing the pump to stop work­ing. Some energy is lost in the cou­pling. This is pri­mar­ily due to some mag­netic re­sis­tance; this is not a sig­nif­i­cant fac­tor in many pump­ing ap­pli­ca­tions.

The re­cir­cu­la­tion flow (a flow form pumped liq­uid) for any mag­net drive pump has three ba­sic func­tions; these are: • Re­moval of the heat gen­er­ated from mag­netic losses. • Lu­bri­ca­tion of the in­ter­nal ra­dial and thrust bear­ings. • Thrust bal­anc­ing of the free float­ing ro­tat­ing assem­bly.

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