Mission Magnum XP- 8x6x18 Centrifugal pump

[chief]

I have been commissioning a series of these pumps and have had overload problems with the drive motors on each, pumping test seawater. The pump curves supplied and the data sheets all check out ON PAPER. I suspect the data supplied by the contractor may be at fault. I have attempted to source the data and pump curves from the ORIGINAL Pump mfr's website , but it is not listed for this particular model. We are operating the pumps at 1475 rpm as on the data sheet. Our power supply is 400V 50 Hertz.
Would appreciate any one who has experience of these pumps supplying their findings. It is intended to use the pumps for drilling Mud at sg up to 2.0.

 

[Artisi]

First question to ask when commisioning pumps and you have an overload situation - are they running in the right direction?

if yes- you need to check flow and head - possibly the discharge head is a lot lower than specified and the pumps are running way-out on their curve.

If they are overloading on seawater - you will have double the problem with the drilling mud at sg 2.


Naresuan University
Phitsanulok
Thailand

 

[JJPellin]

The other potential problem that comes to mind for me is voltage to the motors. If your system is running lower voltage, the motors will draw higher amperage and could trip as a result. You should have an electrician verify the voltage with the pump running under load. If there is a resistance somewhere else in the system the voltage will drop and the amps will take you down.

I am not familar with the configuration of this pump model. If they are standard radial impellers, then high flow (as suggested by Artisi) could be the issue. If they are axial flow or mixed flow impellers, low flow is a potential concern.

Are you sure that your curves and data are for the installed impeller at the speed you are running? We have occasionally ordered pumps and had them tested in one configuration, but shipped in a different configuration. This is done if we have a planned rerate and want to test to the future condition. Perhaps the impellers are larger than the curve and data-sheet indicate.

 

[chief]

I suspect the flowrate given on the data sheet is wrong. Unfortunately I do not have a flowmeter available , but I may overcome this by timing a flow into an adjacent tank. Rpm, pump direction are all ok, but Motor amps are way above FLA.

 

[Jalink]

Chief,

If you want pump curves on the Magmum XP just phone the manufacturer or their local assistance office, which can be found on their website, and ask them for the pump curves of your model.

I do not know the exact requirements for the service intended for this pump. Has this pump for drilling mud to run to the end of curve? Many centrifugal pumps are not equipped with an electric motor of suitable size to allow end of curve operation. The data sheets supplied should detail the intended flow flow range and expected required head.

You do not indicate anything on the head and flow used in test, the intended head and flow on the data sheet and the operation point on the pump curve supplied, which makes it very difficult to understand to problem in detail.

The manufacturer could also give their opinion on the selected electric motor size and the intended operation range.

 

[drillmaint]

With regards to Magnum XP pumps, I've been trying to get the Maintenance manual from National and Halco for over a week. Does anyone know whether the shaft thread is left or right hand thread. We have pumps that have been sitting for 2 years and we need to change impellers on them, unfortunately no manuals or information, and the impeller nose is solid, and I dont want to be forcing it against the thread. Any info would be greatly appreciated.

 

[TenPenny]

I didn't know they made an 8x6-18.

Depending on how the pump and motor were sized, you might be having issues due to viscosity (or lack thereof).

 

[JJPellin]

Drillmaint,

If the impeller is threaded on, it must be threaded so that it tightens with shaft rotation. If it turns clock wise, looking from the coupling toward the impeller, it is right hand thread. If it turns counter-clock-wise, it is left hand thread. If it is curved vanes on the impeller, imagine striking the end of the vane with a hammer. This would unscrew the impeller.

What is the configuration of this pump? I am not familiar with the model. Vertical, horizontal, single stage, multi-stage?