Mag drive pump behaving inconsistently
Mag drive pump behaving inconsistently
(OP)
Mag drive pump tested to 104 Volts (minimum. spec) fails in the field after a brief use. No visible component damage. When the 1400 Gauss magnet is replaced with another 1400 Gauss (or higher)magnet it consistently works. The replaced magnet consistently has a reduced Gauss reading following failure even though the pump passed rigorous tests prior to field placement.
I would appreciate any insight into this failure which we are finding randomly with the pumps.
Thanks.
tyO
I would appreciate any insight into this failure which we are finding randomly with the pumps.
Thanks.
tyO





RE: Mag drive pump behaving inconsistently
Any chance of dry running? What are you pumping?
RE: Mag drive pump behaving inconsistently
Consider TenPenny's comments.
RE: Mag drive pump behaving inconsistently
It fails at 70 deg. F, not just at elevated temp. And, in some cases, it fails as soon as it is installed, after successful pre-field test.
RE: Mag drive pump behaving inconsistently
RE: Mag drive pump behaving inconsistently
RE: Mag drive pump behaving inconsistently
Mike Halloran
Pembroke Pines, FL, USA
RE: Mag drive pump behaving inconsistently
-Dry running which overheats magnets or melts pump
-Product crystallization on shut down (ie, caustic soda)which destroys bearings
Your case seems to involve the magnets becoming demagnetized, which I would think could be caused by overheating, or some odd properties of the fluid, or an environmental/electrical issue.
Off the top of my head, at the bottom of this bottle of wine, I can't think of any obvious causes. Can you provide more details?
RE: Mag drive pump behaving inconsistently
Could there be some conditions when there could be slippage? Perhaps a much stronger magnetic coupling is actually required for your application.
RE: Mag drive pump behaving inconsistently
I have seen these reach some high temps very quickly.
The failure modes are either high temp or slippage.
How are you loading the units in the pre-test? Using a pump or a dyno? How are you measuring the magnet strength?
= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
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RE: Mag drive pump behaving inconsistently
rmw
RE: Mag drive pump behaving inconsistently
RE: Mag drive pump behaving inconsistently
RE: Mag drive pump behaving inconsistently
jet1749 brought up some points that we're yet to look into.
Thanks, all.
RE: Mag drive pump behaving inconsistently
Most common things to effect magnetism of magnets is excessive temperature - we use Somarium Cobalt magnets on metallic pumps which handle tmperatures safely up to 320'C - they can however have a temporary loss in magnetism at temperatures exceeding 260'C and so we have to compensate by adding more magnets. This returns however when returning to lower operating temperatures.
If the pump was to be 'flashing' due to dead heading, you would see additional evidence of wear and damage to bearing material, and possibly face fracture of the ceramic or Silicon faces due to thermal shock etc. The pumped product not only has to lubricate the bearings, but also take away heat generated by eddy current effect (an energy generated by passing magnetic currents through stationery metals). Previous writer was correct, this is worse in Stainless Steel, but you will find most people use Hastelloy for the can as this gives the best efficiency against eddy current loss v cost ratio.
A cheap magnetic drive pump usually consists of low quality magnet materials, which have limits of temperature, limits of torque they can transmit and limits to product density. We often compete against 'cheap pumps' but again, win in the long term, as lifecycle cost is poor.
See if you can find out the material of the magnets from the manufacturer, also see if there is any bearing damage, and also is there is any discolouration of the isolation shell/can which can give many other clues as to what is happening
there is more information available on www.cdrpumps.co.uk if you need further assistance.