Good lord that's beautiful!

Posted this at OCAU.

http://www.employees.org/~slf/images/pqcurves.gif


Some notes:

*) This post was designed for an Australian audience. Ignore the prices listed unless you want a good laugh about how much us Aussies get ripped off on pump pricing.

*) The Danner Mag 3 line is my personal interpretation of a best fit line given the data presented at their website. Their data produces a line that is not even remotely smooth, so I look the liberty to smooth it out somewhat. If anything, I may have overestimated slightly. The in-line heat figure is another approximation drawn from reading about people's experiences. I believe it to be somewhat close.

*) The Swiftech MCP600 in-line heat is another approximation, based on motive pumping power which must be ultimately converted as frictional heat into the water, and some heat from the motor itself.

*) The Johnson pump may be obtained for the price stated from www.depcopump.com. The in-line heat value is an approximation based on my experiences with the Davies-Craig EBP, with both pumps sharings a similar design.

*) The Davies-Craig EBP price quoted is an over-the-counter cash price direct from Davies-Craig. The on-line order price is $201 AUD. (http://www.daviescraig.com.au/newproduct_ebp.asp)

*) The Eheim pumps voltages/frequency is not given as Eheim release correctly spec'ed models for whatever country they are targetted for. This means that so long as you buy the Eheim pump that is correct for your country, you should see the performance stated. The Eheim PQ curves on the literature did not have uniformally placed graph lines. The PQ curves given are based on an interpretation of the graphs using the global min-max scale of the graphs presented, and then following the points on the curve. I believe that this actually eliminates some of the discrepencies with the visual interpretation of the Eheim PQ curves that people have occasionally reported on.

*) The block flow/pressure resistance curves presented are for the blocks themselves only. They do not include additional resistances that may be introduced by a radiator or other heat-transfer device.

That chart of pumps is impressive indeed.

Links to that can be about as helpfull as the heater core data base been for those seeking a good rad. This link will set up those seeking a good pump.

Very impressive.

Cathar, nice graph for the WW & Cascade. But why no curve for the Iwaki MD20rlzt?

LOL - You're the second person to ask for it. I presume you want the 115VAC/50Hz curve for the MD20-RZ?

Okay, re-edited the graph with some assistance for the color-blind (had some complaints about it), and added the 115VAC/50Hz MD20-RZ.

The new graph replaces the old at the site, so if you can't see the updated information then press <shift>+<F5> to refresh it.

From what i see the cascade is more resistive than the white water?
And in this case a 1250 equals a mcp600 for the white water.

Could you put there a cascade + heatercore flow vs pressure grafh?

It would represent a more realistic situation, the mcp would look way better, and the iwaky md20 yummy :)

Yes, Cascade is more restrictive than the White Water. Only the first rev Cascade prototypes were less restrictive. As you can see though, despite being about 50% more restrictive, it typically makes for just a 5-15% difference in volumetric flow rates due to the shape of the curves.

What heater-core?

I use the Camry cores ("Big Arse"). Flow rates with the core attached are typically 5% less than where block lines intersect the pump lines for most scenarios when the math is worked out. The Camry cores have about a 0.7mH2O PD at 10LPM with the 1/2" copper-tube fittings I use.

Thats a 2*120mm fan heatercore right?

Was reading the graphs bad. i guess the diference inst that much.

Can someone explain what the 5 or 6 feet of head is. Is that the pressure or length of distence the pump reaches or maintains the GPH. How the hell does that work. Been reserching and reading for about a year now and I have yet to hear it explained. Probably a n00b question.

Yes, a noob Q, but that's ok. ;)

It's confusing because many different terms are used by various manufacturers. The short answer is that it's the maximum pressure that the pump can deliver.

The long answer is...

It's sometimes called "dead head", because it's the pressure level at which the flow rate becomes zero.

It's also called "head" or "max head", as this max pressure is often expressed as the maximum height of a water column that a pump can sustain.


If you look at any of the PQ graphs above, you'll see a maximum flow rate, and a maximum pressure. Obviously, once you hit the max flow, there's no pressure, and when you hit max pressure, there's no flow...

I ran into a pump test on watercoolplanet.de that seems to indicate that Eheim's specs on the 220V 1046 and 1048 are actually a bit conservative.
It's in German/Deutche. If you don't read that, I've used Systran to produce a translated version and put it here. If you want to grab the numbers, here's the raw spreadsheet. I've edited it by removing unintersting-tome pumps and data columns. I may have totally screwed something up in translation - but I've tried not to.
They've got manafacturer's pump-head specs in bar and observed head in m (and I'm assuming that's m/h2o).
They've also got flow measurements for each pump through 2m of various sized tubing. At least I'm assuming that's what the German means.
I'm a little bit lost with converting flow rates at various restrictions into head/flow figures appropriate for a graph. I'm guessing the first step is to convert a liter of water into a cylinder the diameter of each size of tubing. Because the figures are in l/min, I know how long the "cylinder" is that goes by every minute (measured # of liters times length). This gives me velocity, which I can then use to calculate resistance. I'm pretty sure none of these are fast enough to be "turbulent" which means I should be using ??? to calculate resistance (or maybe just look up in a plumbers' table which might have the advantage of being observed data rather than output of a formula). Have I got that approach right? Anyone got a direct conversion formula (I'm just trying to satisfy my curiosity about the HPPS and data on that pump has been very scanty - it's an amazingly quiet pump, BTW...)
Bob

watercoolplanet.de also says cascade is in 9º place (last time i saw it), and diferenciates waterblocks with 0.1k temp diference, quite impossible to say AFAIK.

You should not take that much seriously.

Oh OK - hadn't looked at their waterblock ratings.
How hard can it be to measure flow through a tube at 0 head, though? I'm pretty sure they got the tube length and diameter right :)

Just took a look at their waterblock ratings. Very strange indeed.
I notice that most of the waterblocks have what appear to be Innovatek-style compression fittings on them.
I have one of those fittings around from an Innovatek agb-o-matic I bought a while back - hmmm... looks like this is intended to fit 8mm ID tubing?
I don't think low flow/pressure is enough to explain their ratings/temps, though...

I think the eheim pumps where tested by phaestus who realised the graphs where optimistic but im not sure.i really dont like the way they test the blocks. Oh well, after seeing the professional way they are tested here, thats something i shouldn't be surprised with...

I also heard that cascade they have there is a "defective" one... never knew what that meant...

It's time for an update.

http://forums.procooling.com/vbb/att...tid=3536&stc=1

to add new pumps? yes indeed.

*deleteeeeed*

how hard @ 0 head ?
I do not know how to do so
some tips ?

Well, in retrospect, I'm not totally sure I do either (semi-old post in old thread recently resurrected with a new post). I've done some reading and thinking about pumps since then.
I think what I was trying to say was "How hard could it be to measure output from a pump, though a measured length of tubing, tubing outlet at the same height as the pump outlet?" (Was thinking about just timing how long it takes to move a gallon, for instance.)
But even that doesn't allow for the residual pressure (positive or negative) coming from the relative elevation of the reservoir (or whatever you want to call the container that's feeding the pump). I'd guess the best you could do to minimize this would be a container with a very large cross-section, with the container outlet near the water surface and the pump inlet on that same level. I'd also guess that another way to do this would be to measure the rate from reservoir through the pump and tubing to the outlet without turning the pump on. Still not right as an unmoving rotor is going to present some resistance (much more if it's a closed rotor). Maybe remove the rotor for this measurement, try to keep pump inlet pressure slightly positive, and then subtract this flow from whatever the pump produces when running.

So - do I think WCP actually did any of this? I dunno. Probably not, though... IMHO the best we can hope for is that they used the same reservoir source setup for all the pumps in their spreadsheet so at least those numbers are comparable to each other. Might be a forlorn hope at that.

yea, tricky setup needed - with more tricks than I have

A loop with aux.pump>target pump>valve>flowmeter>. Have pressure sensors at the inlet and outlet of the target pump, and use the valve to the throttle the flow to the point that dP across the target pump is zero.

nope, have to throttle the aux pump too
kinda interactive

I'll google it later

There are lots of pump curves published by pump manufacturers.
What exactly do they (the pump mfgrs) do to get these curves?
Bill - maybe you could call the manufacturer of the Swiftech pump and ask them for some guidance? It's a good pump and any kind of fair measurement between pumps is (IMHO) going to show it off very well, so hopefully they won't feel any urges towards obsfucation.
There might even turn out to be different "standard" ways to define water column height, which might explain some of the discrepancies we see.
I've just gone looking across pump manufacturer/distributor web sites, and ran across some (IMHO) very good tech intros at Goulds Pumps - particularly Introduction to Pumps Reading Curves (IMHO+BTW appropriate for the ProCooling "links" section). There's mention in there of a Hydraulic Institute - and it looks as though they are working on some pump output measurement standards (looks a lot like ANSI - in that you don't get to look at the standards unless your organization "joins"). Maybe the manufacturer Swiftech is dealing with is already a member(?) Think it's worth asking?
Bob

That's what the valve does, throttles the aux to the point where the pressure it produces is equal to the drop from the valve/flowmeter/piping and its flow is equal to the target's 0-head flow.

The 0 head point is not of much use if one is testing pumps for our purposes anyway.

A question though: Would anyone believe me if I were to test a well-regarded pump and its P-Q curve were substantially (a) worse or (b) better than the mfgr P-Q curve? MAYBE a few people, but not many. So I put pump testing down low on the priority list. Exception would be 12V pumps over a wide range of voltage/PWM; THAT would be useful and interesting to many.

sorry Groth, I misunderstood
was thinking to generate the entire curve

pH
for sure there is some sort of ind std, I'll dig it up
the truly serious ones I have are in Hungarian, and for an old product

bobkoure
the data from Laing is the best I've seen, but the stds cited are not available here (or in English ?)

Well, yeah - but how do you get 1' right if you don't know how to get 0?
You're right that it should be low on your priority list.

You could generate the whole curve that way. But after the target's dP excedes the equipments', the risk of inaccuracy from injecting turbulence into the target's inlet reduces the aux's value.

MCP-350 Update
 

Since the MCP-350 is now on Swiftech's site I figure it's time for an updated graph for this official pump thread.

http://forums.procooling.com/vbb/att...tid=4210&stc=1