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Help on Witness Testing

Help on Witness Testing

Help on Witness Testing

Hello there,

I am a fresh grad. and have been tasked with conducting pump testing of a submersible rotodynamic pump.

The test supervisor will be responsible for carrying out the majority of the tests, so I am mostly there as an observer only. However, I am keen to do well and was wondering if there is anything in particular that I should be looking out for during the witness testing?
(PS: I have read the relevant british standards ISO9906:1999)

Many thanks

RE: Help on Witness Testing

A lot will depend on where the pump test is being undertaken as to what you should be "looking " for during the test.
Is it being tested in a test facility or is it a site test.
If it is a test facility (certifiable pump test tank) you only need to be interested in the test meter accuracy and the correction factors for pump measuring point to gauge point, power frequency and voltage etc etc..
If it is a site test this is a different ball game, beside the above you will need to look at pump inlet conditions (stable flow conditions to the pump), accuracy of measurement for each test point, any change to operating conditions throughout the test, ie, is the pump submergence constant, is voltage constant etc.
From my experience, it is unlikely that will you reproduce "test" results during a site test unless extreme care and accuracy is maintained.
For a site test you should be interested in testing around the duty point only and not trying to reproduce the full operating curve.    
Hope this is of some helps to you.     

RE: Help on Witness Testing

I'm not familiar with "submersible rotodynamic" pump, but you should also ask if any modifications were done to the pump in order to make it meet performance.  The test shop will likely run the test in advance of your arrival and therefore have time to make correction if needed.  Overfilling and underfilling, polishing, (as on centrifugals) etc may be done if the "standard" parts don't meet spec.

RE: Help on Witness Testing

  See Thread407-26917 which addressed a similar question in mid 2002.

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