Water flow switch
 

http://www.overclockers.com/tips1114/

An excellent idea: easy to build, and uses my favorite parts (PVC fittings, and scrap parts!).

The article is very well detailed too!

Nice one Ron!

Nice article. Only problem I see is in the image I attached.

Yeah that paddle looks way to big - Maybe a smaller paddle would do.

Well, in theory you could just connect the switch to a 555 based circuit. Feed everything from a fan header and you'll have a auto shutdown .

When the switch is off, the square wave stops. The rest is just tweaking the frequency. And adding the thing to the MBM our similar program.

Something to try in the future :) .

did you guys read the article?
He purposefully uses PVC that has a larger ID than your normal hoses so that despite the look, there is little flow restriction. he then measures it, and gets a result that the paddles adds a 2% flow reduction.

Yeah I read it. :shrug: 2% is 2% to much but my main point was no place to stick that beast inside a "normal" case.

I still don't understand why people bother with flow switches. All you have to do is setup a thermal switch and stick it under the water block somewhere, anywhere will work on the block, deson't HAVE to be next to the die. If the block gets over a set limit it shuts off the entire system. No flow restritction, no size restriction, and it can be worked into other monitoring devices...

Well, there's enough info in the whole article to re-design the float to something slimmer, and still keep it working.

One could simply use a "blade" that cuts into the flow, to minimize the pressure drop.

I still say a magnetic flowmeter with an alarm output is the way to go.
If you don't want to add hardware simply use MBM with shutdown.exe proggy at whatever trip point you want.

But at what price?

Yeah, magnetic flow meter $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ $$$$.

Been looking at those for my test bench. I seen a decent one for $300.

Thermal shutoff is the better option IMO. Once the flow stops it doesn't take long for the base of the water block to heat up. Epoxy or even tape a thermal cut off sensor to the base and have it hooked into a relay to shut the system down when it reaches whatever point. That way you get around the mother board software shutoff which isn't reliable (been there recently). Flow switches are unecassary overkill IMO.

sometimes, free (helps to have Yokogawa, Rosemont & ABB stuff here at work)

but really, they CAN be had used, sometimes on ebay or surplus sites, just have to look & jump quick

I was digging through www.overclockers.com water cooling stuff and organizing the links to put in my site and discovered this article:

http://www.overclockers.com/tips642/index02.asp