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Pump Selection (Mags vs Canned)

Pump Selection (Mags vs Canned)

Pump Selection (Mags vs Canned)

Hi, we are in the process of installing new pumps to replace old centrifugal ones(with mechanical seals). As we face some internal tight environmental regulations, we focus on zero emission pumps.
Now, we have the proposal from differents manufacturers on Mag and canned pumps, and the investment cost are quite similar.
We have to dig a little on technical issues and I like to know or discuss which are the main points to be analyzed when comparing both technologies.
Thanks in advance

RE: Pump Selection (Mags vs Canned)

There's a good article comparing canned motor and mag drive pumps by Foszcz,J.L. ((1993), "Canned Motor Pumps", Plant Engineering, June 3, 1993, pp. 62-66. Among the advantages of canned motor pumps are fewer radial bearings which are long-lived fluid film bearings. Dry stators with thin-walled stator cans are preferred over oil-flooded stators.Stator can integrity is a concern since failure will wet the winding insulation and lead to motor winding dielectric failures. Also you must apply sufficient fluid pressure in the rotor-stator gap to keep the stator can seated against its backup structure which should not have wide gaps that can cause strain concentration in the can over the gaps leading to premature can fatigue failures. Motor coolant process fluid temperatures need to be kept below about 230-250F for bearing and motor winding reliability with canned motor pumps. If the pumped process fluid is at much higher temperatures, then a thermal barrier structure must be interposed between the pump casing and the motor's rotor cavity. If this causes appreciable impeller shaft overhang of the motor's lower radial bearing , then rotor dynamics problems could ensue including internal seal rubbing at the thermal barrier. The higher the power rating of canned motor pumps, the more complex and critical these problems become.  

RE: Pump Selection (Mags vs Canned)

Articles on magnetic drive and canned motor pumps were published in Pumps and Systems magazine in Feb./May/Sept 1999 . The same magazine had sealess pump articles in Mar./ July/ Aug. 1994, May 1995, May 1996, June/Aug./Nov. 1997, May/June 1998. I think its www.pumpzone.com on the internet and they do have some articles from earlier issues that can be read.

RE: Pump Selection (Mags vs Canned)

That is great vanstoja! Do you have those papers scanned?

RE: Pump Selection (Mags vs Canned)

Correction- The website is www.pump-zone.com.
quark-No I don't have these articles scanned for e-mail transmission. If you want to provide a USA business mailing address I can send you copies by snail mail.

RE: Pump Selection (Mags vs Canned)

We have pre-selected three differents manufacturers of mag drive pumps for our services:

DURCO Guardian

Prices & performance seem to be quite similar (at least in theory ) but I would like to know your experiences with some of this models
Thanks in advance

RE: Pump Selection (Mags vs Canned)

whb (Mechanical) Nov 30, 2002
 v hv chemical dosing diaphragm pumps for dosing chemicals like nalco into the feed water tank of waste heat boiler.Recently the diaphragm got punctured??Can i know the reason y this happened, when the pump is discharging only 1.5 bar pressure and its a very new pump?even what r the different quality of diaphragms??

RE: Pump Selection (Mags vs Canned)

We are looking for nuclear class 1 canned motor pumps operaterating at high temperature and pressure, does anyone know a good reputable manufacturer of such pumps.

RE: Pump Selection (Mags vs Canned)

In regards to the last two replies. You would do better at getting response if you post a new thread.

Roy Gariepy
Maintenance and Reliability Dept.
Bayer Corporation  Dorlastan Fibers Div.
Goose Creek, South Carolina  USA

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