Drop out of magneticaly coupled pump.

[FixingIt]

I am involved in a project which supplied a low volume water pump with a magnetic coupling, to feed a dissolved oxygen analyser. The client has installed the pump, in their offshore application, but reports the pump loosing suction after a few seconds of operation. I suspect the position of the magnetic coupling components may be critical, but our supplier is slow to respond with technical assistance. I need to give our client some clear guidance as to what adjustments they can make. Many thanks.

 

[jet1749]

My experience of mag-dive pumps has been with monobloc types (unitized) in the chemical industry, primarily for acid or caustic tank transfer or recycling duties so excuse me if yours is a different type.
I have found that if you get de-coupling of the magnets you are in some trouble. Generally the coupling power rating is greater than the motor in order to protect the magnets. De-coupling of the magnets whilst the motor is running can generate significant heat, this heat affects the magnets and reduces their strength. If you catch it before too much heat is generated the magnetic strength can return, if you're too late the magnetic strength can be totally lost. If you have access to the operating manual it should give you the static break-out torque of the coupling assembly, which can vary according to the magnets used. Typically these can be Neodymium or Samarium Cobalt magnets. A clearer description of the pump and its duties may get you some more specific information.
Regards
John