View Full Version : Watercooling Flow Meter

Z3RO 0
05-11-2002, 08:56 PM

Has anyone used a flow meter in there watercooling setup befor?
I was thinking about using one to make sute the system is going - My computer runs 24/7 so the last thing i want is for the cooling to fail in the night and fry the CPU

Where would be a good source for bits like a flow meter and some valves ( for a fill-and-blead closed system )

Thanks, Z3RO 0

05-11-2002, 09:04 PM
I saw a simple review a while ago for a flow meter using a 80mm fan with 2 peices of perspex on the sides of it, and water in/out drilled through sides (the fan will be screwed though) but its a basic flow meter :)

THG did one a while ago with a proper/retail flow meter..

05-11-2002, 09:05 PM
I know that u can make one up out of a "Hall sensor" out of a DC brushless fan, and run a piezo alarm or light to show you if u have flow or not. The article is on Overclockers.com watercooling articles. I will probably end up making something simliar as i dont want the flow to stop when im running 2 x 172 watt pelts 24/7...

Z3RO 0
05-11-2002, 09:16 PM
The main reson i wanted it was to hook up to a relay, and then the AC power that inputs directley to the computers PSU, so if anything goes rong whith the water flow ( too slow to cool / completley stops ) the computers power will be cut

Hopefulley saving the computer if anything happens to go rong

BTW, anyone know where i could get valves from and other fittings - i nede them to make up a fill-and-bleed valve thing - my watercooler is going to be closed circut, no water tank

Z3RO 0

Z3RO 0
05-11-2002, 09:31 PM
Also, Would anyone knowwhere to get 'Water Wetter' from in Christchurch

And where to buy flow meters from, As i want to make sure my watercooling is leek-proof :)


05-11-2002, 09:39 PM
well, water wetter is hard to find :p i ended up just buyign coolant/antifreeze from repco...

also dont fish tanks use flow meters? i'm pretty sure they do...
i'm thinking about ordering one from US, maybe if you're interested i can get one for you as well if i do get one :)

they hook onto your cpu fan sensor so basically does the same job :o

me's been lookign for those things for a while ;)

after reading the 'hto to make your own flow meter with a relay' thingy, i find myself once again too lazy to make one :rolleyes:

Z3RO 0
05-11-2002, 09:50 PM
Yeah, I'd be interested in geting one aswell :)

Whats the link for the DIY one, Just wanna check it out and see how they work :P

Anyway, For fittings would standard ones from a plumbing shop be ok ( right sise of cource ;) )

Im going to make like 'Water Spliters' so it would split the output of the pump into say 5 pipes, to cool all the stuff in the case, then all the hot water coming back from the stuff in the case would go into another spliter to merdge them all the pipes into one pipe again, then go into the radiator and back into the pump

Im thinking about making the spliters out of perspex ( If anyone wants to see a digram of how, I'll post it :) )

If you want a good place to get perspex call 'Fab Plastics' I get all my perspex from them, its REALL cheep - I got the stuff for my new clear side for my computer from them. Cost about $20 for the perspex and $10 for the perspex glue

Z3RO 0

05-11-2002, 11:04 PM
dude, i dont want to ***** or anything-
but is your english REALLY that bad?

now back on topic.

go on, post people...

06-11-2002, 09:10 AM
Originally posted by Z3RO 0
Im going to make like 'Water Spliters' so it would split the output of the pump into say 5 pipes, to cool all the stuff in the case, then all the hot water coming back from the stuff in the case would go into another spliter to merdge them all the pipes into one pipe again, then go into the radiator and back into the pump

Im thinking about making the spliters out of perspex ( If anyone wants to see a digram of how, I'll post it :) )

Yeah.. most of us have seen Bladerunner's work ;)

http://www.zerofanzone.co.uk/pictures/jpg/xp750wc078s.jpg (http://www.zerofanzone.co.uk/largepic.asp?pic=xp750wc078l&ext=jpg)

06-11-2002, 09:21 AM
there was a thread about this one old forums and the general feeling after a bit of research was that they're not really worth it.

you can order flow meters from just about any reputable plumbing supplies store, or you can order then through RS components. either way, most of them are very expensive and although there are cheaper ones available they pretty much all tend to have a significant effect on flow rates :(

and the thing is they're not really all that neccessary unless you're using peltiers, in which case you should be prepared for a disaster anyway... if the flow stops your CPU temps don't rise rapidly, infact quite the opposite as most waterblocks do quite a good job of simply sinking the heat off anyway, and as you'll almost always be running well below 60C in normal conditions, you can just set your overheat protection to switch your machine off at 60C you'll be fine.

Z3RO 0
06-11-2002, 11:05 AM
Thanks for that ( Sorry about the English - I don't really bother when i'm typing large posts :P )

Yeah, I got the idear of the spliters from that image when I saw it a while ago :)

The mobo i have in it is an ASUS A7M266-D, I think it has thermal protection on both the CPU's, But i dont know if you can set the temp for it to cut the power

06-11-2002, 04:33 PM
yea, wouldnt a watercooling rig turned off have a sort of heat-pipe effect aswell?

06-11-2002, 04:50 PM
well, i found that the flow meters are gonna cost about $80 (NZ$) + P&P from US :/ i'm still gonna get one, but if anyone else is up for paying a price like that, feel free to PM me :)

also the non mobo connector ones for about $18 US$

Z3RO 0
06-11-2002, 05:03 PM
Check your PM's :)

06-11-2002, 10:32 PM
Hi guys, It's true most commercial flow meters are either far too expensive or restrict the flow down to a tiny hole. They also mostly work by spinning an impeller which makes a noise. As we are only after a flow "monitor" not a flow "meter" as such, this is my auto shutoff system, works really well using this, (cheapish, 13 UK), flow switch shown below, bought from RS in the UK, which uses the same principal as the proximity switch shown in my previous posting in this topic HERE (http://www.over-clock.co.uk/cgi-bin/ikonboard/ikonboard.cgi?act=ST&f=24&t=14&st=15)


Here's my description of how it works:-

Inside the tube it has a small plastic cylinder which sits on the base of the unit positioned in the branch off part. Inside this plastic cylinder is a small magnet. The "cap" at the top of the Y branch has a proximity switch. When the pump is not running the plastic cylinder sits on the base of the unit so the contacts of the proximity switch remain open. When the pump is on the flow pressure makes the cylinder rise up into the branch so causing the proximity switch to close contacts.

The output from this is run to a "pulse Generator" unit which is a small cheap & simple electronic circuit I made, (with much help from others), to mimic a fans sensor output, so I could use the original "Smart Doctor" utility with my Water-cooled Asus GeForce 3, (with the GF3's fan removed, smart doctor would pop up all the time saying the fan was dead, and there was no way to disable it).

Here is an image of the "pulse gen"


It plugs into the CPU fan header on the motherboard. The sensor output from the "pulse gen" is run through the flow switch so when the pump is running the motherboard reads about 3000rpm just as if a fan is plugged into it. If the pump dies or the flow is interrupted by coolant loss, or flow is low etc, the cylinder in the flow switch will drop down and the proximity switch inside will go open circuit cutting the sensor output to the fan header. This will cause the bios to read 0 rpm and instantly shut the PC down if the bios option is set to "shutdown on CPU fan fail".

I've since found there is a slight problem with this on my motherboard, (Abit KX7 333R), in that the bios setting for "shutdown when CPU Fan fail" doesn't actually work, (It is enabled). It's also nothing to do with my "pulse gen system" because even with no fan connected it doesn't shutdown. I'm therefore using "Motherboard Monitor (http://mbm.livewiredev.com/)" with "Shutdown now (http://www.shutdownnow.de)" set to force shutdown in 0 seconds on no CPU fan rotation. This works fine and shuts off the PC within a few seconds if the Pump or flow is stopped. A bit of an ass about face way of doing it, but until I can find out why the bios setting doesn't work it will do.

The flow switches can be found on the UK RS site, (http://www.rswww.com), by typing this code C257076 into the search feature.

You don't have to use a pulse gen, but can just use a fan as long as it can be run from the motherboard CPU fan header. If you are fanless like myself, then here is the circuit diagram for the pulse gen, with components required.


Wire trace colours used mainly just to show where they pass each other but are not joined, (they are only joined with a circle).

more detail on this in the linked topic at the beginning

06-11-2002, 11:20 PM
/Bows down

Damn that is an elegant solution

Z3RO 0
07-11-2002, 01:56 PM
I think I found somthing that may be usefull


But, They are out of stock - I think they can order more in so it should be ok :)

Z3RO 0

07-11-2002, 04:12 PM
i like blade runner's one too :) but don't think i'm the type who would do the wiring... so innova it is unless someonw would like to be paid to do one for me :D

Z3RO 0
07-11-2002, 07:04 PM
Where is Blade Runners one? A picture of it

Is it a DIY one?

07-11-2002, 09:53 PM
Originally posted by Z3RO 0
Where is Blade Runners one? A picture of it

Is it a DIY one?
ummm, go back a page in this thread ;)

he uses a flow switch from RS (i think i remember seeing theseon the NZ RS components site) mated to a homemade hall sensor emulator circuit.

certainly the best way to do it if you're ever going to. it won't give you flow info (who needs it anyway? ;)), but it'll work with your favourite monitor app to shutdown your computer if the flow stops.

07-11-2002, 11:34 PM
Z3RO 0

I maybe missing something here but originally you wanted a system to protect your PC from pump death or flow loss when you are sleeping?. The visual unit you link to is just that, only a visual unit, so will only be any good if you are watching it so that you can manually shut the system off.

If you don't need to have a fanless solution the pulse gen unit is not required. It is then very simple to wire up all you need to do is cut one wire and make two wire joins. This very poor sketch should make it clear, if not ask.


This will mean when the pump is creating flow the contacts in the flow switch will be closed so the fan will output it's RPM to the motherboard in the conventional way via the flowswitch. If flow stops, or drops too low, pump dies, coolant loss etc the contacts in the flow switch will open so the fans rpm output will be switched off causing the mobo to read zero rpm just as if the fan had stopped working, (although the fan will still be running).

The only other things you will need are Motherboard monitor (free), and shutdown now which is free for 2 weeks then costs $19 USD, (make sure you buy it because it doesn't tell you it's stopped working it just pops up a window rather than shutting down). At least you'll have two weeks to get it working and decide if it's what you want.

So total cost:-

Fan (I'd assume you had one but $5)
Flow switch $18
shutdown now $19

total $37 usd without fan, plus a few hours work and maybe some tube and tube clamps.

not much for piece of mind ;)

(if anyone does this, motherboard monitor wont allow a setting of 0 seconds to shutoff on CPU fan fail, lowest is 10 seconds but it's quite easy to edit the inf, ask if you need to know how).

The beauty is it will power your system off in the correct way if you are not around in event of a failure, so saving your data. If I were running a high watt TEC I'd probably make the system just power off the PSU instantly to be safe.

Not that you can see much but here is my flow switch fitted and "working"


08-11-2002, 06:51 AM
hmmm... looks like i'll be doing that then :p
i mean... the innovatec one is too expencive for what it is :(

so where do i hook up the fan sensor wire to? (onto the commercial flow meter)

hang on a min... is the yellow wire on the Tt RAMsink fan a speed sensor? if so i can use that :)

08-11-2002, 07:25 AM
I'm not using a fan, but I guess you can use any fan that has a rotation wire, (usually yellow), as long as it doesn't overload your CPU fan header power output. Think of it as the fan being plugged into your CPU header on the mobo in the conventional way. It will now report an RPM value related to it's speed in the bios and a windows app like Motherboard Monitor.

All you are doing with the flow switch is, putting a make or break contact in the fans sensor wire. With the flow switch in the cooling circuit. flow = make so mobo receives rotation info, no flow, or low flow = break mobo gets no rotation info.

With no rotation info mobo and bios will see the fan as being dead, If your bios shuts off your system while in windows with a dead fan you wont need the motherboard monitor / shutdown now thing, just enable the bios setting. I think most of these shutdown on CPU fan fail bios options only work on boot up, mine doesn't work at all like said even with no fan connected so???

The flow sensor I've pictured in this topic comes in two sizes of pipe diameter 15mm & 22mm. you'll need to find a away to incorporate it into your system, it can also only be mounted in certain ways too, but magnetic proximity switches are extremely reliable in use as long as the contacts are not overloaded, (don't try switching the mains voltage with one for instance).

The flow switch has two wires. All you do is cut the fan sensor wire in the middle, (we are only talking about a three wire three pin fan plug not the larger PSU 4 pin). You've now got one wire, (usually yellow or white), coming from the fan, connect this to one of the two flow sensor wires. The other end of the wire you'd just cut goes to the three pin mobo header plug, connect this to the other wire from the flow sensor. You can test it before plumbing the flow switch into the water cooling system if you like, by connecting it up as explained then starting the PC and while watching the motherboard monitor high & low screen hold the flow sensor upside down. A fan RPM should be reported, now turn the Flow switch the correct way up, this will cause the contacts in the switch to open and cut the fans reported RPM, if it's all working / connected correctly. I can take some pics if it helps anyone, but I assure you it is very simple...... the hardest part I guess will be fitting and connecting the flow sensor to your specific cooling system.

*edit* to incorrect flow sensor wiring detail as I was thinking about another proximity switch I have in my set-up :rolleyes: )

Z3RO 0
08-11-2002, 11:51 AM
Himm, I'd still like to go whith the Innovatek ( If thats spelt right :P ) one as im sure its ganna work and it would also be able to tell me the water speed

-DC- Where was it you were going to get yours from?

08-11-2002, 01:12 PM
For those that want it I found the Flow Switches on the NZ RS site HERE (http://nz.rs-c.dk/servlet/dk.stibo.module.ShowModuleServlet?moduleId=5157808 ) :)

08-11-2002, 01:18 PM
cheers for that man, i might grab one...

Z3RO 0
08-11-2002, 01:52 PM
Anyone knoe where to get the Innovatek ones?

08-11-2002, 02:09 PM
You'll have to order one from the states .....

08-11-2002, 03:42 PM
Z3RO 0: Why do you want to go to the hassle and expensive of getting the Innovatek thang.. when Bladerunner has just laid down some excellent info...

A clever, simple and elegant mod..

Oh well to each their own I suppose

08-11-2002, 04:10 PM
Originally posted by Ragnor
Z3RO 0: Why do you want to go to the hassle and expensive of getting the Innovatek thang.. when Bladerunner has just laid down some excellent info...

A clever, simple and elegant mod..

Oh well to each their own I suppose

yeah ragnor is right, and i DID pont our before i don't want an innovatec one anymore if oyu did read my post properly.

08-11-2002, 04:20 PM
Yup.. I know ya did.. you'll notice I referred to Z3RO only

08-11-2002, 04:39 PM
Still costs quite abit. 46 bux ex p&p i guess.

You could hook it up to your radiator fan couldnt you? or is it only a 2 pin fan? Is there any way of using the rpm switch without a fan?

ps. Ragnor (man i allways thught it was rangor) Z3R0 was odering it thu -DC- and -DC- said he wasnt going to buy one therefore Z3R0 wont get one.... thru -DC- anyway.

08-11-2002, 05:15 PM
Originally posted by Method
ou could hook it up to your radiator fan couldnt you? or is it only a 2 pin fan? Is there any way of using the rpm switch without a fan?
geez man... go back and re-read bladerunners posts carefully... all is explained.

Z3RO 0
08-11-2002, 05:24 PM
-DC- Can you please tell me where you were going to order from - as i still want to get one but dont know the site for them

Thanks, Z3RO 0