Backyard Aquaponics
A place to discuss aquaponics

Randomly saw this and thought you guys might like it http://amzn.com/B000X05G1A

It's usually $100 so it seems to be a pretty good deal. Please note that I have not used/tested/bought this pump.

Cheers!

The efficiency sucks. Max is <25%

it was $100 once, but for a very short time (probably when it was out of stock once). this price is pretty much its regular price.
http://camelcamelcamel.com/Superior-Pum ... B000X05G1A

Stu - how did you work out efficiency on that pump? What flow rate are you assuming the 1/4hp rating applies to?

I've just been trying to work out pump efficiency and have only found this

http://www.tunze.com/149.html?&L=1&C=GB ... oxunter051

I did an effciiency curve from the data and was surprised how much lower the efficiency was on the smaller model. Though it seems that to be able to calc efficiency as a minimum you need the zero flow and full flow power consumption figures, and then assume a linear increase between these two points. Would be quite simple to test on an actual pump with a power meter.

This is what I calc'ed....

Tunze 3000L/h silence pump curves
head L/h Pin(W) Pout(W) efficiency
3 0 16 0 0.00%
2.5 500 20 3.40625 17.03%
2 1000 25 5.45 21.80%
1.5 1500 28 6.13125 21.90%
1 2000 33 5.45 16.52%
0.5 2500 37 3.40625 9.21%
0 3000 42 0 0.00%

Tunze 2000L/h silence pump curves
head L/h Pin(W) Pout(W) efficiency
2 0 14 0 0.00%
1.5 550 17 2.248125 13.22%
1 1200 22 3.27 14.86%
0.5 1800 26 2.4525 9.43%
0 2400 30 0 0.00%

..
I would have assumed the only way to start to consider efficiency, is to know the POWER for each effective HEAD
( ie head plus friction )

PS - I would have to think about what "0" percent efficiency means, other than it ain't a pumping nuffin..
..
.

I agree....and it seems very hard to get power/head curves for pumps other than measuring.

I didn't include kinetic energy of the water in my calc, so if you are not raising the water in height, the power out term is zero.

In efficiency calculations for pumps you are only concerned with the head versus flow of the pump friction doesn't come into it.

Or rather the friction component is included in the head. There are lots of ways of looking at this but in this sense you don't consider pumps to be machines that move water, rather you consider them to be machines that develop pressure on water and then the pressure moves the water.

When measuring the effectiveness of pumps there are standard apparatus that are used. One of these involves the ability to attach the pump directly to a silo tank. ie you have a tank that is very tall and rather wide. For higher pressure pumps it is VERY tall. How wide the tanks need to be is determined by the size of the pump but the idea is that the velocity of the water in the tank is stuff all (technical term). The pump is attached to the silo tank directly, ie there are no intermediate fittings and when switched on it begins to fill the tank. Once the tank is full then you know the maximum pressure the pump can develop or looking at it from the other direction the maximum height it can pump water to. Then on the other side of the tank is an outlet with a VERY fine control linear valve and a VERY accurate flow meter.

Over time the valve is gradually opened a step at a time and not changed until the height has stopped dropping and then the flow is measured and the valve opened another step.



Since we are talking about the amount of work being done the pump could be pumping millions of liters per second using only a handful of watts (ie an airlift) but if it is only lifting the water 1/1000th of a smidgen of a millimeter then the amount of work would be approximately 0 which would mean the amount of work (almost 0) divided by the amount of watts (a handful) would be a very, very... ...very, very, very small number divided by a relatively large number would therefore be ~0.

So how did you work out the efficiency Stu

On the one I got off ebay?

I increased the pipe size connected to the pump to 2" and then added a junction. The straight arm went to the FT and the take off was positioned vertically and I attached a clear pipe to it so I could measure the water height in the pipe.

This gave me a reasonable measure of both the pressure shortly after the pump and I measured the flow into the FT. The power draw I measured with a plug in current meter.

Ahh, OK that makes sense - from the thread above it looked like you magically discerned efficiency from limited data. Might have a play with my DW3000's to see how they come out.

After a recent discussion with Stuart, I've just bought a 1% accuracy, 160kPa gauge with 100mm dial, and I should be able to read it to a precision of ~1kPa, which is accurate enough for the efficiency testing I'll be doing on the 48V DC pump in my new system sometime soon.

I'm looking forward to the results.

Hopefully they are efficient it would make a great option for a lot of people.

Depending on the price that is.

Stu,

Didn't you have an excel sheet on the good pumps bad pumps thread to work out pump efficiency?