TDH of Vertical Turbine pumps 1

[impeller1]

Folks,

Another question here. I am a young Engineer and I'd like to know how you would go about determining the TDH of a vertical pump in operation. I'd like to perform a test on a pump to determine how it actually performs with respect to its design pump curve. It won't be 100 % accurate as I don't have the system curve, but i'd still like an idea about what to do. Thank You.

 

[TenPenny]

I think you'll need to measure the discharge pressure (at discharge centerline) and the water level (usually referenced to the floorplate).

 

[JohnGP]

Yes, that's about it - see link for an example -

http://www.gouldspumps.com/pag_0027a .html.

If you are using a pressure gauge on the discharge, then adjust the reading back to the reference datum.

With a flow rate reading, you will be able to see how closely the pump is performing to its curve under your test conditions. It may be possible to plot a few points on the curve if you can partially shut in a valve in the discharge line.

The accuracy of the results depend on how accurately you are measuring levels and/or pressures, and flow. You may only need to plot the system curve (which is usually not that difficult) if the operating point that you plot on the pump curve doesn't match the design point, and you want to investigate where things may have gone wrong.

Cheers,
John

 

[MartinSr00]

Note the fluid temperature. Determine the specific gravity at that temperature.

Determine the deltaP between suction and discharge.

From the pipe sizes, determine the fluid velocity at your suction and discharge measurement points. These measurement points are best located on the suction and discharge flanges.

If DP=delta P between suction and discharge
SG = specific gravity of fluid
Vs = suction pipe velocity in feet/sec
Vd = discharge pipe velocity in feet/sec
g = accel due to gravity in ft/sec^2

H = DP/(2.31 x SG)+(Vd^2-Vs^2)/2*g

That should get you pretty darn close.

Make sure you bleed the water in your gauge lines. If your pressure measurements are from two different guages, make sure they are both at the same height.

 

[BigInch]

MartinSr Wrong Formula

Try this one (not including the velocity terms)

dH_ft = dP_psig * 144_in^2 /(SG * 62.4 lbf/ft^3)


**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[JohnGP]

When are you guys going to use metric - it's so much easier. And MartinSR00, it's not necessary to have suction and discharge gauges at the same height - it's a simple matter to adjust the readings back to pump centreline, or other datum. Admittedly we don't have all the detail, but as this was about a vertical turbine pump, then there is likely no suction pressure gauge (or suction piping).

 

[BigInch]

Metric for us is just a whole lot more conversion factors you have to remember.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[JohnGP]

We've been there before - I won't hijack the thread.

 

[MartinSr00]

BigInch -- Metric is great. But whenever I looked around in the pump industry here in America it's gpm or cfs and ft of head.

Guage corrections: True enough, but then the explanation to impeller1 would have to be more complex and I'd have to explain further the correction. If it's a DP cell, it could be at any height. But if you're going to do it formally and use two gauges, as you say, each pressure should be corrected to the datum per the Hydraulic Institute Standard (or some other agreed upon standard).

In the one formula up above I put one of the factors on the wrong side of the divide:

H = DP x 2.31/SG+(Vd^2-Vs^2)/2g

Note you have to account for the differential velocity head if the inlet and outlet pipes are of different size. Often, the difference is small, but not always.

 

[BigInch]

After 20+ years , actually I'm fluent in both. I hardly remember deg F, however I have yet to receive a pump curve with head in meters and flow in m3. Furthermore, concerning almost any topic (non electric related), there is so much more info-data available in EGS than there is in MKS, so Katmar's Uconeer "unit converter" software is the hottest shortcut on my desktop .... which makes converting pump curves to varas v. tonnes per annum a relatively simple operation. Personally I don't care much for kPa OR bars, as the first is way too small and barg is way too big.

I note that in the UK a few discontinuities persist ... the left-hand side of the road, steering on the right, but the pedals in the same position as in left-handed cars, with the accelerator on the right, CW roundabouts. ... All speed limits and distances are given in miles and mph, so I don't see where Brits have a right to talk about international standards. If it wern't for them, we wouldn't have this situation today anyway.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[impeller1]

Thanks for info people

 

[dabluffrat]

Impeller1

find a copy of Hydraulic Institute ANSI/HI 2.6-2000 for vertical pump testing. Good reference and walks you through the corrections, definitions, and calculations.

Did you know that 76.4% of all statistics are made up...

 

[JohnGP]

Hey BigInch, I didn't realise that you were so young! I grew up with imperial, but have come to love the simplicity of working in metric. And the fact that car's pedals are the same was a welcome discovery the first time that I had to drive a LH drive car.

 

[BigInch]

I wish. 20+ as an expat.
At least we're driving on the right side here.
I can't hardly cross the street in London.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[Artisi]

BigInch, don't bother trying to cross the road - just stay in the one pub instead of wandering round aimlessly risking the chance of getting run-over.

 

[BigInch]

"<-- Look Left" signs are a great help.
I really almost got killed in Perth (Australia, not Scotland). I got halfway across a 4 lane street when I remembered to look left... just in time for a quick couple of backsteps.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[Artisi]

You really need to watch those ("sand-groper's) Western Australians, it's so sparcely populated they are only used to dodging round the occasional kangaroo.

 

[Compositepro]

I knew a plant safety manager from California who was visiting a customer in England. He stepped off the curb at Heathrow and was hit by a bus. He almost died. He was flown home after two weeks in hospital. He looked the wrong way.

 

[JohnGP]

See it's all about Pommie drivers.......even Perth (Aus) is full of them!

 

[Artisi]

We call the "South Pacific pommies"