Determining Flow- Meter, Pressure?

[voigts]

Ok, I have spent a couple of hours trying to find out how one can go about determining what actual flow rate a watercooling loop is running at. I would like to be able to see what difference different pumps/configurations make on my system. I also am wondering if pressure is a good gauge of how your loop is running. For instance, is it really worth $80 for another pump. I have an extra MCP650 that I would like to hook up and if it makes a measurable difference, sell and replace with a 50z to match the 50z I already am running (dual pumps), or maybe sell them both and go with matching MCP350s.

I have read several threads here on OC and elsewhere and it seems that whenever anyone has asked this question, they do not receive a concrete answer (particularly with flow rate). I have seen several posts of "here is what I have done" that takes some serious electronics know-how (which I don't have), other technical stuff about how to get a perfectly accurate reading for benchmarking, or gauges that cost $200+. I have also seen the "why would you want to restrict your loop" answers. Innovatek seems to be the only one to make anything for watercooling regarding flow, but it is only a "it flows or it doesn't" deal and works on like 1/4" tubing.

What can you get that is reasonably inexpensive to do this? I haven't been able to find an answer. I was looking at this: http://www.flowmeters.com/products/index.cfm?task=prod_detail&prod_id=505#preconfig
but am really not sure if it would do the trick. I don't have to have something that I have installed all of the time, but something that you could use to at least get an idea of where you are.

[David]

How about set up your loop, and fill it. Then remove the inlet to your res and have it so the water flows from this part into a container, with markings every, say, 0.25 litres. Then keep a tub of water spare. Run the pump for 5 minutes (use a stopwatch), keeping the res topped up, and then see how much water was pumped into your collecting tub during those 5 minutes. Divide by 5 and you have flowrate in litres/min.

[Craptacualr]

Yup, bucket stopwatch test is what we refer to it in the lab. You could also weigh the bucket if you cant measure volume... First weigh it dry, then weigh it full. Convert lbs to kg (www.onlineconversion.com) and remember 1kg = 1Liter of water. divide by time for Liters per minute. And if you want, convert L/min to g/min, or hour or whatever you want.

EXTREMELY IMPORTANT! you HAVE to maintain the water level of the supply resevior at a certain height AND the outlet of the bucket HAS to be at the same height through out all tests. Like, even a couple inches of height difference will make huge differences in flowrate because you're running an open loop. I've got TONS of experience with this, so if you need questions, please feel free to ask. I do this for a living ;)

[nikhsub1]

voigts, really it makes not a whole lot of difference. You will spend lot's of time for something that has been worked out already. Here is one thread to refer to with a snippet from Cathar regarding different pumps using a G4 and a dual Rad with 2M tubing.

http://forums.procooling.com/vbb/showthread.php?t=10825&page=1&pp=25

A snippet from it from Cathar:

+20.7C => Iwaki RD-30 @ 18.0v
+20.8C => 2 x Swiftech MCP600 @ 13.8v (series)
+20.9C => Swiftech MCP600 @ 13.8v
+21.1C => Iwaki MD-20RZ @ 60Hz
+21.1C => 2 x Swiftech MCP600 @ 12.0v (series)
+21.2C => Iwaki MD-20RZ @ 50Hz
+21.4C => Swiftech MCP600 @ 12.0v
+21.4C => 2 x Eheim 1048 (series)
+21.5C => Iwaki MD-15R @ 60Hz
+21.6C => Laing DDC @ 13.2v
+21.6C => Swiftech MCP650 @ 12.0v
+21.6C => Iwaki MD-30RZ @ 50Hz
+21.7C => Iwaki MD-30RZ @ 60Hz
+21.9C => Eheim 1250
+22.1C => Laing DDC @ 12.0v
+22.3C => Eheim 1048
+23.3C => Eheim 1046

Here are various flow rates with different pumps with the same components (A G5 is also included).

[Craptacualr]

I agree with Nikshub in that such research is very time consuming and should really only be undertaken by the enthusiast with lots of time/money on his/her hands. It can be done for sure, but it takes a lot of time and effort

[itchy5]

nikhsub1 has it right, if you have a good pump you should expect 1.3gpm-1.5gpm fully loaded loop, just an estimate :santa: :rolleyes:

[voigts]

that is a lot of good info. I have read however several posts on here about people that have added a second pump and seen like 5c reduction in temps, and several swear by using dual pumps, yet according to Cathar's tests, it doesn't seem to make that much difference. yet his testing is done with merely a cpu block and then later a chipset block I think with a 120.2 . But the question remains, is there an inexpensive way to get an idea of what kind of flow rate you are getting?

And does the bucket test really give you an idea that is half-way accurate as you are opening up the system and thereby taking any pressure out of the "equation" so to speak.

[MVC]

Well, I tend to be an empiricist, so... couldn't you just hook up the second pump you already have and see what difference, if any, it makes to your temps?

Oh, and that flow meter you linked to starts at 3 GPM and if you look at Cathar's graph you'll see that few pumps actually have that high a flow rate in a system. If you want to experiment with a meter you'd need one that goes down to at least .5 GPM.

FWIW, a DD D4 with nothing in a ~2' loop will get somewhere around just over 3 GPM (the second meter in the pic dropped the flow an additional ~.3 GPM from the reading with just one meter, so with no meter installed....). And, with the margin of error with these meters "real" flow could be anywhere from 2.75 to, maybe, 3.4 GPM.

But, again, the real measure of the usefulness of a second pump would be if your temps decrease, not an estimate of the flow rate.

[voigts]

Your reply MVC makes sense and is more what I am looking for. Not only is it a matter of trying a second pump, but i would also like to be able to tell if for instance certain tube routing, fittings, etc. really make a difference on flow or not. I think that there is information on the forums that sometimes seems to me to be passed around rather than really supported. For instance, I have read over and over that 90 degree bends are "flow killers", which has never really made much sense to me. It seems to me that if you are using 5/8" elbows with 1/2" ID with 1/2"ID tubing that it really shouldn't make much of a difference. It also just seems odd to me that we talk about flow over and over on the forums and spend lots of time and effort trying to improve flow to improve temps but sometimes seem to me to be guessing as to what really works in a given setup.

What are those flow meters that you have in the pic? Do you have a link?

[MVC]

Your reply MVC makes sense and is more what I am looking for. Not only is it a matter of trying a second pump, but i would also like to be able to tell if for instance certain tube routing, fittings, etc. really make a difference on flow or not. I think that there is information on the forums that sometimes seems to me to be passed around rather than really supported. For instance, I have read over and over that 90 degree bends are "flow killers", which has never really made much sense to me. It seems to me that if you are using 5/8" elbows with 1/2" ID with 1/2"ID tubing that it really shouldn't make much of a difference. It also just seems odd to me that we talk about flow over and over on the forums and spend lots of time and effort trying to improve flow to improve temps but sometimes seem to me to be guessing as to what really works in a given setup.

What are those flow meters that you have in the pic? Do you have a link?

The flow meters are Dwyer Instruments VFB-86-SS models, here's a link: http://www.dwyer-inst.com/htdocs/flow/SeriesVFA-VFBPrice.cfm and select 4" meters with stainless fittings.

These really aren't the best meters for measuring flow in water cooled PCs (accuracy leaves something to be desired and float meters have too great an impact on flow rates at the flow rates we actually have), but a good magnetic flow meter is several hundred dollars, so.... BTW, I've only got these because I spotted them real cheap on ebay a while back and wound up with a box of them for something like 15 cents on the dollar. And, of course, they are better than nothing :)

[voigts]

I PMed you.

I noticed some Blue Water Flowmeters online that are in the range that you mention. I may also look into them.